Silver-aluminium filled conductive elastomer (EMI gasket) Ag/Al elastomer
Silicone (CHO-SEAL 1285) or fluorosilicone (CHO-SEAL 1287) elastomer binder filled with silver-plated aluminium particles, printed as Ag/Al
Also known as CHO-SEAL 1285, CHO-SEAL 1287
Silver-aluminium filled conductive elastomers are EMI shielding gaskets for enclosure seams.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Shielding
At least 100 dB at 10 GHz
Conductivity
0.0080 ohm-cm
Temperature
200 °C in air
Recipe, share of the weight
- Mass share not printed in the sources readSilicone or fluorosilicone elastomer binder
- Mass share not printed in the sources readSilver-plated aluminium particles (Ag/Al)
Best for
Enclosure seams in military and aerospace electronics that need a conductive gasket to MIL-DTL-83528 (CHO-SEAL 1285, Type B, at least 100 dB at 10 GHz, plane wave)
Weakest at
Long-term corrosion and shielding loss: the sources give only general galvanic guidance, and no outgassing, flight or chemical-resistance result for CHO-SEAL 1285 or 1287 was read in this run
Risk at a glance
- People None found. Not checked
- If it fails Moderate. Galvanic corrosion at the gasket-to-housing interface
- Corrosion Moderate. The Modus guide says thermal cycling and galvanic effects together can reduce shielding by several dB over a mission.
Quick facts: Ag/Al elastomer
| Property | Value | Basis |
|---|---|---|
| Density | 1.75 to 2.25 g/cm³ | 2 sourced values across conditions |
| Tensile strength | at least 1.24 MPa | 2 sourced values across conditions |
| Thermal conductivity | 2.2 W/(m·K) | 1 sourced value |
| Electrical resistivity | 0.00008 to 0.00015 Ω·m | 4 sourced values across conditions |
| Maximum service temperature | 200 °C | 2 sourced values across conditions |
What is the density of Silver-aluminium filled conductive elastomer (EMI gasket)?
Silver-aluminium filled conductive elastomer (EMI gasket) has a density of 1.75 to 2.25 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the thermal conductivity of Silver-aluminium filled conductive elastomer (EMI gasket)?
Silver-aluminium filled conductive elastomer (EMI gasket) has a thermal conductivity of 2.2 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Silver-aluminium filled conductive elastomer (EMI gasket)?
Silver-aluminium filled conductive elastomer (EMI gasket) has a tensile strength of at least 1.24 MPa. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the maximum service temperature of Silver-aluminium filled conductive elastomer (EMI gasket)?
Silver-aluminium filled conductive elastomer (EMI gasket) has a maximum service temperature of 200 °C. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What are the other names and codes for Silver-aluminium filled conductive elastomer (EMI gasket)?
Silver-aluminium filled conductive elastomer (EMI gasket) is also written as CHO-SEAL 1285, CHO-SEAL 1287. Each code is printed in the source listed beside it in the designations table.
What is Silver-aluminium filled conductive elastomer (EMI gasket) used for?
Uses recorded in the sources include EMI gasket on enclosure flanges and covers in military electronics (MIL-DTL-83528 scope); EMI gasket for satellite electronics enclosures (vendor guidance, no flight result read).
Why it exists
Conductive elastomer EMI gaskets seal an enclosure seam and carry its shielding current across the joint. CHO-SEAL 1285 and CHO-SEAL 1287 are Parker Chomerics silver-aluminium filled gaskets built to the MIL-DTL-83528 specification. The 1285 has a silicone binder and is listed as Type B, with at least 100 dB of plane-wave shielding at 10 GHz. The 1287 has a fluorosilicone binder and is listed as Type D, with at least 90 dB at 10 GHz. The choice between them depends on the binder and the shielding frequency needed.
Where it's used
Military and aerospace electronics
The MIL-DTL-83528 specification covers electrically conductive elastomeric shielding gaskets that give low interface resistance between enclosure flanges or covers and also provide environmental sealing. CHO-SEAL 1285 is listed as a Type B material to that specification.
Satellite electronics (vendor guidance only)
A Modus Advanced guide on space-qualified EMI gaskets for satellite shielding discusses silver/aluminium fillers for this use. The guide does not give a flight result for these two grades.
Recipe
Silicone (CHO-SEAL 1285) or fluorosilicone (CHO-SEAL 1287) elastomer binder filled with silver-plated aluminium particles, printed as Ag/Al
CHO-SEAL gaskets are a conductive elastomer: a cured silicone or fluorosilicone binder filled with silver-plated aluminium particles, printed as Ag/Al. The binder gives the rubber sealing and resilience; the filler gives the electrical conductivity. Shares of binder and filler are not printed in any source read.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Silicone or fluorosilicone elastomer binder | Mass share not printed in the sources read | The rubber matrix. It gives the gasket its hardness, elongation and sealing; CHO-SEAL 1285 uses a silicone binder and CHO-SEAL 1287 a fluorosilicone binder. |
| Silver-plated aluminium particles (Ag/Al) | Mass share not printed in the sources read | The conductive filler. Silver on aluminium particles provides the electrical path that gives the shielding and the low volume resistivity. |
Weight shares are as printed in the sources.
What it can do
Shielding
At least 100 dB at 10 GHz
measured
Per the CHO-SEAL 1285 listing, the minimum plane-wave shielding effectiveness is 100 dB at 10 GHz (1.00e+10 Hz) and 110 dB at 500 MHz for the E field. The 1287 listing gives 90 dB at 10 GHz and 100 dB at 500 MHz for the E field.
Conductivity
0.0080 ohm-cm
measured
The 1285 listing prints a volume resistivity of 0.0080 ohm-cm without pressure-sensitive adhesive, and 0.015 ohm-cm after tensile set. The 1287 listing prints 0.012 ohm-cm and 0.015 ohm-cm.
Temperature
200 °C in air
measured
Both listings print a maximum service temperature in air of 200 °C. The 1285 minimum is -65 °C and the 1287 minimum is -55 °C, both per the Flex TR10 and ASTM D1329 test named on the pages.
How it compares
This profile compares two grades from one manufacturer rather than other shielding materials. CHO-SEAL 1285 (silicone, Type B) lists at least 100 dB at 10 GHz and 0.0080 ohm-cm volume resistivity. CHO-SEAL 1287 (fluorosilicone, Type D) lists at least 90 dB at 10 GHz and 0.012 ohm-cm. The two grades are not interchangeable: the binder changes the shielding minima and the resistivity as printed.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | Ag/Al elastomer |
|---|---|
| Thermal behavior and safety | |
| Thermal conductivity, CHO-SEAL 1285 | 2.2 W/m-K4 |
| Volume resistivity after heat ageing, CHO-SEAL 1285 | < 0.01 ohm-cm14 |
| Volume resistivity after heat ageing, CHO-SEAL 1287Maximum printed as '<0.015 ohm-cm' | < 0.015 ohm-cm29 |
| Lifetime and stability | |
| Volume resistivity after vibration, CHO-SEAL 1285Maximum printed as '<0.008 ohm-cm' | < 0.008 ohm-cm15 |
| Volume resistivity during vibration, CHO-SEAL 1285Maximum printed as '<0.012 ohm-cm' | < 0.012 ohm-cm16 |
| Volume resistivity after vibration, CHO-SEAL 1287Maximum printed as '<0.012 ohm-cm' | < 0.012 ohm-cm30 |
| Volume resistivity during vibration, CHO-SEAL 1287Maximum printed as '<0.015 ohm-cm' | < 0.015 ohm-cm31 |
| Physical and electrical | |
| Specific gravity, CHO-SEAL 1285 (silicone binder) | 1.75 to 2.25 g/cc1 |
| Hardness, Shore A, CHO-SEAL 1285Range printed with test method ASTM D2240 | 58 to 72 Shore A |
| Volume resistivity, CHO-SEAL 1285 | 0.008 ohm-cm7 |
| Volume resistivity after tensile set, CHO-SEAL 1285Value printed for the post-tensile-set condition | 0.015 ohm-cm8 |
| Specific gravity, CHO-SEAL 1287 (fluorosilicone binder) | 1.75 to 2.25 g/cc17 |
| Hardness, Shore A, CHO-SEAL 1287Range printed with test method ASTM D2240 | 63 to 77 Shore A |
| Volume resistivity, CHO-SEAL 1287 | 0.012 ohm-cm21 |
| Volume resistivity after tensile set, CHO-SEAL 1287 | 0.015 ohm-cm22 |
| Other measurements | |
| Tensile strength at break, CHO-SEAL 1285Minimum printed with test method ASTM D412 | > 1.38 MPa2 |
| Elongation at break, CHO-SEAL 1285Range printed with test method ASTM D412 | 100 to 300 % |
| Tear strength, CHO-SEAL 1285Typical value printed with test method ASTM D624 | 5.25 kN/m |
| Compression set, CHO-SEAL 1285 | < 32 %3 |
| Maximum service temperature in air, CHO-SEAL 1285 | 200 °C5 |
| Minimum service temperature in air, CHO-SEAL 1285 | -65 °C6 |
| Shielding effectiveness, CHO-SEAL 1285, 200 kHz H fieldMinimum printed as '>= 60 dB' in the listing | > 60 dB9 |
| Shielding effectiveness, CHO-SEAL 1285, 500 MHz E fieldMinimum printed as '>= 110 dB' in the listing | > 110 dB10 |
| Shielding effectiveness, CHO-SEAL 1285, 100 MHz E fieldMinimum printed as '>= 115 dB' in the listing | > 115 dB11 |
| Shielding effectiveness, CHO-SEAL 1285, 2 GHz plane waveMinimum printed as '>= 105 dB' in the listing | > 105 dB12 |
| Shielding effectiveness, CHO-SEAL 1285, 10 GHz plane waveMinimum printed as '>= 100 dB' in the listing | > 100 dB13 |
| EMP survivability, CHO-SEAL 1285Minimum printed as '>0.9 kA / in' | > 0.9 kA/in |
| Tensile strength at break, CHO-SEAL 1287Minimum printed with test method ASTM D412 | > 1.24 MPa18 |
| Elongation at break, CHO-SEAL 1287Range printed with test method ASTM D412 | 60 to 260 % |
| Tear strength, CHO-SEAL 1287Typical value printed with test method ASTM D624 | 6.13 kN/m |
| Compression set, CHO-SEAL 1287 | < 30 %19 |
| Maximum service temperature in air, CHO-SEAL 1287Value printed; no test method given on the page | 200 °C |
| Minimum service temperature in air, CHO-SEAL 1287 | -55 °C20 |
| Shielding effectiveness, CHO-SEAL 1287, 200 kHz H fieldMinimum printed as '>= 55 dB' in the listing | > 55 dB23 |
| Shielding effectiveness, CHO-SEAL 1287, 500 MHz E fieldMinimum printed as '>= 100 dB' in the listing | > 100 dB24 |
| Shielding effectiveness, CHO-SEAL 1287, 100 MHz E fieldMinimum printed as '>= 110 dB' in the listing | > 110 dB25 |
| Shielding effectiveness, CHO-SEAL 1287, 2 GHz plane waveMinimum printed as '>= 95 dB' in the listing | > 95 dB26 |
| Shielding effectiveness, CHO-SEAL 1287, 10 GHz plane waveMinimum printed as '>= 90 dB' in the listing | > 90 dB27 |
| Shielding effectiveness, CHO-SEAL 1287, 40 GHz plane waveMinimum printed as '>= 75 dB' in the listing | > 75 dB28 |
| EMP survivability, CHO-SEAL 1287 | > 0.9 kA/in32 |
Why choose it, and why not
Good for
- Enclosure seams that need a conductive gasket to MIL-DTL-83528. CHO-SEAL 1285 is listed as Type B with at least 100 dB at 10 GHz.
- Seams that must stay conductive through vibration: volume resistivity after vibration is printed as below 0.008 ohm-cm for CHO-SEAL 1285.
Watch out for
- Galvanic pairing: the Modus guide says the filler suits aluminium housings but the pairing still needs plating or matching to avoid contact-resistance rise over time.
- Thermal cycling: the guide says shielding can fall by several dB over a mission. No time or dB figure is given.
- Outgassing and flight data: none were read for these two grades, so their suitability for vacuum use is not established by these sources.
CHO-SEAL 1285 and 1287 are MIL-DTL-83528 silver-aluminium gaskets with printed shielding minima and volume resistivity. The sources read give listing values only: no Parker datasheet, outgassing, hazard or flight data could be checked in this run.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| Trade name | CHO-SEAL 1285, CHO-SEAL 1287 |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Specific gravity, CHO-SEAL 1285 (silicone binder) | Range printed as specific gravity with test standard ASTM D792 (the page labels it specific gravity, not density) | product CHO-SEAL 1285temperature not printed on the page | — |
| 2 | Tensile strength at break, CHO-SEAL 1285 | — | product CHO-SEAL 1285printed as 1.38 MPa or more (200 psi or more)test ASTM D412 | — |
| 3 | Compression set, CHO-SEAL 1285 | Maximum printed with test method ASTM D395 Method B | product CHO-SEAL 1285temperature 100 °Ctime 252000 sec (70.0 hours as printed)test ASTM D395 Method B | — |
| 4 | Thermal conductivity, CHO-SEAL 1285 | Value printed with test method ASTM D5470 at the stated pressure | product CHO-SEAL 1285pressure 2.07 MPa (300 psi as printed)test ASTM D5470 | — |
| 5 | Maximum service temperature in air, CHO-SEAL 1285 | Value printed; the page lists the test method as Not listed | product CHO-SEAL 1285environment air | — |
| 6 | Minimum service temperature in air, CHO-SEAL 1285 | Value printed with test method Flex TR10; ASTM D1329 | product CHO-SEAL 1285environment airtest Flex TR10; ASTM D1329 | — |
| 7 | Volume resistivity, CHO-SEAL 1285 | Value printed with the test named in the conditions | product CHO-SEAL 1285state without pressure-sensitive adhesivetest MIL-DTL-83528 | — |
| 8 | Volume resistivity after tensile set, CHO-SEAL 1285 | — | product CHO-SEAL 1285state post tensile settest MIL-DTL-83528 | — |
| 9 | Shielding effectiveness, CHO-SEAL 1285, 200 kHz H field | — | product CHO-SEAL 1285frequency 200 kHzfield H fieldstandard MIL-DTL-83528 Para. 4.6.12 | — |
| 10 | Shielding effectiveness, CHO-SEAL 1285, 500 MHz E field | — | product CHO-SEAL 1285frequency 5.00e+8 Hz (500 MHz)field E fieldstandard MIL-DTL-83528 Para. 4.6.12 | — |
| 11 | Shielding effectiveness, CHO-SEAL 1285, 100 MHz E field | — | product CHO-SEAL 1285frequency 1.00e+8 Hz (100 MHz)field E fieldstandard MIL-DTL-83528 Para. 4.6.12 | — |
| 12 | Shielding effectiveness, CHO-SEAL 1285, 2 GHz plane wave | — | product CHO-SEAL 1285frequency 2.00e+9 Hz (2 GHz)field plane wavestandard MIL-DTL-83528 Para. 4.6.12 | — |
| 13 | Shielding effectiveness, CHO-SEAL 1285, 10 GHz plane wave | — | product CHO-SEAL 1285frequency 1.00e+10 Hz (10 GHz)field plane wavestandard MIL-DTL-83528 Para. 4.6.12 | — |
| 14 | Volume resistivity after heat ageing, CHO-SEAL 1285 | Maximum printed as '<0.01 ohm-cm' in the Descriptive Properties table | product CHO-SEAL 1285test MIL-DTL-83528 Para. 4.6.15exposure not printed on the page | — |
| 15 | Volume resistivity after vibration, CHO-SEAL 1285 | — | product CHO-SEAL 1285test MIL-DTL-83528 Para. 4.6.13timing after vibration | — |
| 16 | Volume resistivity during vibration, CHO-SEAL 1285 | — | product CHO-SEAL 1285test MIL-DTL-83528 Para. 4.6.13timing during vibration | — |
| 17 | Specific gravity, CHO-SEAL 1287 (fluorosilicone binder) | Range printed as specific gravity with test standard ASTM D792 | product CHO-SEAL 1287temperature not printed on the page | — |
| 18 | Tensile strength at break, CHO-SEAL 1287 | — | product CHO-SEAL 1287printed as 1.24 MPa or more (180 psi or more)test ASTM D412 | — |
| 19 | Compression set, CHO-SEAL 1287 | Maximum printed with test method ASTM D395 Method B | product CHO-SEAL 1287temperature 100 °Ctime 252000 sec (70.0 hours as printed at 212 °F)test ASTM D395 Method B | — |
| 20 | Minimum service temperature in air, CHO-SEAL 1287 | Value printed with test method Flex TR10; ASTM D1329 | product CHO-SEAL 1287environment airtest Flex TR10; ASTM D1329 | — |
| 21 | Volume resistivity, CHO-SEAL 1287 | Value printed with the test named in the conditions | product CHO-SEAL 1287state without pressure-sensitive adhesivetest MIL-DTL-83528 | — |
| 22 | Volume resistivity after tensile set, CHO-SEAL 1287 | Value printed for the post-tensile-set condition; the page prints the standard as MIL-G-83528 | product CHO-SEAL 1287state post tensile settest MIL-DTL-83528 Para. 4.6.9 as printed | The page prints the standard reference as MIL-G-83528 in this row and MIL-DTL-83528 elsewhere. |
| 23 | Shielding effectiveness, CHO-SEAL 1287, 200 kHz H field | — | product CHO-SEAL 1287frequency 200 kHzfield H fieldstandard MIL-DTL-83528 Para. 4.6.12 | — |
| 24 | Shielding effectiveness, CHO-SEAL 1287, 500 MHz E field | — | product CHO-SEAL 1287frequency 5.00e+8 Hz (500 MHz)field E fieldstandard MIL-DTL-83528 Para. 4.6.12 | — |
| 25 | Shielding effectiveness, CHO-SEAL 1287, 100 MHz E field | — | product CHO-SEAL 1287frequency 1.00e+8 Hz (100 MHz)field E fieldstandard MIL-DTL-83528 Para. 4.6.12 | — |
| 26 | Shielding effectiveness, CHO-SEAL 1287, 2 GHz plane wave | — | product CHO-SEAL 1287frequency 2.00e+9 Hz (2 GHz)field plane wavestandard MIL-DTL-83528 Para. 4.6.12 | — |
| 27 | Shielding effectiveness, CHO-SEAL 1287, 10 GHz plane wave | — | product CHO-SEAL 1287frequency 1.00e+10 Hz (10 GHz)field plane wavestandard MIL-DTL-83528 Para. 4.6.12 | — |
| 28 | Shielding effectiveness, CHO-SEAL 1287, 40 GHz plane wave | — | product CHO-SEAL 1287frequency 4.00e+10 Hz (40 GHz)field plane wavestandard MIL-DTL-83528 Para. 4.6.12 | — |
| 29 | Volume resistivity after heat ageing, CHO-SEAL 1287 | — | product CHO-SEAL 1287test MIL-DTL-83528 Para. 4.6.15exposure not printed on the page | — |
| 30 | Volume resistivity after vibration, CHO-SEAL 1287 | — | product CHO-SEAL 1287test MIL-DTL-83528 Para. 4.6.13timing after vibration | — |
| 31 | Volume resistivity during vibration, CHO-SEAL 1287 | — | product CHO-SEAL 1287test MIL-DTL-83528 Para. 4.6.13timing during vibration | — |
| 32 | EMP survivability, CHO-SEAL 1287 | Minimum printed as '>0.9 kA / in' with the test paragraph named on the page | product CHO-SEAL 1287test MIL-DTL-83528 Para. 4.6.16 | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Silver/aluminium filler in contact with aluminium housings (galvanic exposure) | low | Silver/aluminium fillers pair well with aluminium housings and reduce galvanic risk, according to a Modus Advanced guide on space-qualified EMI gaskets.1 |
| Thermal cycling combined with galvanic exposure over a mission | moderate | The Modus guide says thermal cycling and galvanic effects together can reduce shielding by several dB over a mission.2 |
| Heat ageing at the MIL-DTL-83528 test condition | low | After heat ageing, the listed volume resistivity stays below 0.01 ohm-cm for CHO-SEAL 1285 and below 0.015 ohm-cm for CHO-SEAL 1287.3 |
| Corrosion resistance claim on the CHO-SEAL 1285 listing | not rated | The CHO-SEAL 1285 listing describes the material as having improved corrosion resistance but gives no test figure for it.4 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Silver/aluminium filler in contact with aluminium housings (galvanic exposure) | The guide's filler table rates silver/aluminium as good with aluminium housings, and its galvanic section says the filler reduces galvanic risk. It also says plating the housing with nickel or tin improves galvanic compatibility. No corrosion test on CHO-SEAL 1285 or 1287 was read. | basis general vendor guidance, no test condition, exposure time or product namedhousing aluminium |
| 2 | Thermal cycling combined with galvanic exposure over a mission | The guide states that the combination of thermal cycling and galvanic effects can reduce shielding effectiveness by several dB over the life of a mission, and that wrong filler and housing pairings can increase contact resistance over time. The guide gives no dB figure or time for this loss. | basis vendor statement, no mission duration or dB figure givenproduct silver/aluminium filled gaskets in general |
| 3 | Heat ageing at the MIL-DTL-83528 test condition | The Descriptive Properties tables of both Chomerics listings print a heat-ageing resistivity limit under MIL-DTL-83528 Para. 4.6.15. The exposure temperature and time are not printed on the pages, so the limit cannot be tied to a service life. | basis maximum limits as printed; exposure temperature and time not printedstandard MIL-DTL-83528 Para. 4.6.15 |
| 4 | Corrosion resistance claim on the CHO-SEAL 1285 listing | The listing's Material Notes say 'Conductive Elastomer with Improved Corrosion Resistance'. The page does not name the comparison material, the test or the result, so the claim is recorded as printed and not rated. | basis manufacturer claim as printed on a reseller listingcomparison not stated |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
No safety data sheet for CHO-SEAL 1285 or 1287 was read in this run, so their own hazard classification is not recorded. PubChem GHS data for the constituent silver and aluminium metals is in the hazards section.
- Hazard data
- The sources read give no hazard classification for these two gasket grades. Read the supplier's safety data sheet for the exact part before handling.
If it fails
The failure routes in the sources read are electrical: loss of shielding and contact resistance over time.
- Galvanic and thermal
- The Modus guide says wrong filler and housing pairings can raise contact resistance over time, and that thermal cycling plus galvanic effects can reduce shielding by several dB over a mission. It gives no time or dB figure.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Galvanic corrosion at the gasket-to-housing interfacemoderate severity | Silver/aluminium filler in contact with a housing that is not plated or otherwise matched, in a humid or thermally cycled environmentThe Modus guide says wrong filler and housing pairings can lead to increased contact resistance over time, which reduces shielding. |
| Shielding loss from thermal cycling over a missionmoderate severity | Repeated thermal cycling of a gasket seam over the life of a missionThe guide says the combined effects can reduce shielding effectiveness by several dB over the life of a mission. No dB value or time is given. |
Mitigations
- Plate aluminium housings with nickel or tin to improve galvanic compatibility, as the Modus guide recommends for silver/aluminium gaskets.
Supply and geography
How common the raw materials are and where they come from.
Silver (filler metal)
Not read in this run. The USGS silver chapter was read for production, reserves and recycling only.
- Top producers (2025)
- Mexico 24.2%, Peru 13.8%, China 13.1%, Bolivia 5.8%, Chile 5.4%
- Critical mineral lists
- US: listed
- Recycling
- USGS: about 1,000 tons of silver was recovered from new and old scrap in the United States in 2025, about 11% of apparent consumption.
- Substitutes
- USGS: aluminum and rhodium may replace silver in mirrors and reflecting surfaces. The chapter names no substitute for silver in conductive elastomers.
Aluminium (filler base metal)
Not read in this run.
- Top producers (2025)
- China 60.8%, India 5.7%, Russia 5.3%, Canada 4.5%, United Arab Emirates 3.6%
- Critical mineral lists
- US: listed
- Recycling
- USGS: about 3.6 million tons of aluminum was recovered from purchased scrap in the United States in 2025, equivalent to about 28% of apparent consumption from old scrap.
- Substitutes
- USGS: copper can replace aluminum in electrical and heat-exchange applications.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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spore: profile
id: conductive-elastomer-silver-aluminium
spore_version: 0.2
family: conductive-elastomers
name: Silver-aluminium filled conductive elastomer (EMI gasket)
abbreviation: Ag/Al elastomer
role: EMI shielding gasket for enclosure seams
category: shielding
type: spot-shields
summary: |
Silver-aluminium filled conductive elastomers are EMI shielding gaskets for enclosure seams. Parker Chomerics CHO-SEAL 1285, with a silicone binder, is a MIL-DTL-83528 Type B material printed with at least 100 dB of plane-wave shielding at 10 GHz and a volume resistivity of 0.0080 ohm-cm. CHO-SEAL 1287, with a fluorosilicone binder, is a Type D material printed with at least 90 dB at 10 GHz and 0.012 ohm-cm. Both figures come from a reseller listing that attributes its data to Chomerics; no Parker datasheet could be opened in this run.
best_for: Enclosure seams in military and aerospace electronics that need a conductive gasket to MIL-DTL-83528 (CHO-SEAL 1285, Type B, at least 100 dB at 10 GHz, plane wave)
weakest_at: 'Long-term corrosion and shielding loss: the sources give only general galvanic guidance, and no outgassing, flight or chemical-resistance result for CHO-SEAL 1285 or 1287 was read in this run'
identity:
formula: Silicone (CHO-SEAL 1285) or fluorosilicone (CHO-SEAL 1287) elastomer binder filled with silver-plated aluminium particles, printed as Ag/Al
source: lp-chomerics-1285
where: 'CHO-SEAL 1285 page, Descriptive Properties (Binder: Silicone; Filler: Ag/Al); CHO-SEAL 1287 page, Descriptive Properties (Base polymer: Fluoro-silicone; Filler: Ag/Al) and Material Notes (silver-plated-aluminum-filled fluorosilicone elastomer)'
designations:
- system: Trade name
code: CHO-SEAL 1285
source: lp-chomerics-1285
where: Page title and Trade Name field
- system: Trade name
code: CHO-SEAL 1287
source: lp-chomerics-1287
where: Page title and Trade Name field
tags:
environments: []
stresses:
- thermal-cycling
- vibration
applications:
- electronics-and-chips
properties:
- benchmark: density
label: Specific gravity, CHO-SEAL 1285 (silicone binder)
value: 1.75
value_high: 2.25
bound: range
unit: g/cc
scope: material
conditions:
product: CHO-SEAL 1285
temperature: not printed on the page
method: Range printed as specific gravity with test standard ASTM D792 (the page labels it specific gravity, not density)
status: ground
source: lp-chomerics-1285
where: Physical Properties table, Specific Gravity row
- benchmark: hardness_shore_a
label: Hardness, Shore A, CHO-SEAL 1285
value: 58
value_high: 72
bound: range
unit: Shore A
scope: material
conditions:
product: CHO-SEAL 1285
scale: Shore A
method: Range printed with test method ASTM D2240
status: ground
source: lp-chomerics-1285
where: Mechanical Properties table, Hardness, Shore A row
- benchmark: ultimate_tensile_strength
label: Tensile strength at break, CHO-SEAL 1285
value: 1.38
bound: lower
unit: MPa
scope: material
conditions:
product: CHO-SEAL 1285
printed_as: 1.38 MPa or more (200 psi or more)
test: ASTM D412
method: Minimum printed with test method ASTM D412
status: ground
source: lp-chomerics-1285
where: Mechanical Properties table, Tensile Strength at Break row
- benchmark: elongation
label: Elongation at break, CHO-SEAL 1285
value: 100
value_high: 300
bound: range
unit: '%'
scope: material
conditions:
product: CHO-SEAL 1285
test: ASTM D412
method: Range printed with test method ASTM D412
status: ground
source: lp-chomerics-1285
where: Mechanical Properties table, Elongation at Break row
- benchmark: tear_strength
label: Tear strength, CHO-SEAL 1285
value: 5.25
unit: kN/m
scope: material
conditions:
product: CHO-SEAL 1285
printed_alongside: 30.0 pli
method: Typical value printed with test method ASTM D624
status: ground
source: lp-chomerics-1285
where: Mechanical Properties table, Tear Strength row
- benchmark: compression_set
label: Compression set, CHO-SEAL 1285
value: 32
bound: upper
unit: '%'
scope: material
conditions:
product: CHO-SEAL 1285
temperature: 100 °C
time: 252000 sec (70.0 hours as printed)
test: ASTM D395 Method B
method: Maximum printed with test method ASTM D395 Method B
status: ground
source: lp-chomerics-1285
where: Mechanical Properties table, Compression Set row
- benchmark: thermal_conductivity
label: Thermal conductivity, CHO-SEAL 1285
value: 2.2
unit: W/m-K
scope: material
conditions:
product: CHO-SEAL 1285
pressure: 2.07 MPa (300 psi as printed)
test: ASTM D5470
method: Value printed with test method ASTM D5470 at the stated pressure
status: ground
source: lp-chomerics-1285
where: Thermal Properties table, Thermal Conductivity row
- benchmark: max_service_temp
label: Maximum service temperature in air, CHO-SEAL 1285
value: 200
unit: °C
scope: material
conditions:
product: CHO-SEAL 1285
environment: air
method: Value printed; the page lists the test method as Not listed
status: ground
source: lp-chomerics-1285
where: Thermal Properties table, Maximum Service Temperature, Air row
- benchmark: min_service_temp
label: Minimum service temperature in air, CHO-SEAL 1285
value: -65
unit: °C
scope: material
conditions:
product: CHO-SEAL 1285
environment: air
test: Flex TR10; ASTM D1329
method: Value printed with test method Flex TR10; ASTM D1329
status: ground
source: lp-chomerics-1285
where: Thermal Properties table, Minimum Service Temperature, Air row
- benchmark: electrical_resistivity
label: Volume resistivity, CHO-SEAL 1285
value: 0.008
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1285
state: without pressure-sensitive adhesive
test: MIL-DTL-83528
method: Value printed with the test named in the conditions
status: ground
source: lp-chomerics-1285
where: Electrical Properties table, Volume Resistivity row (first)
- benchmark: electrical_resistivity
label: Volume resistivity after tensile set, CHO-SEAL 1285
value: 0.015
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1285
state: post tensile set
test: MIL-DTL-83528
method: Value printed for the post-tensile-set condition
status: ground
source: lp-chomerics-1285
where: Electrical Properties table, Volume Resistivity row (second)
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1285, 200 kHz H field
value: 60
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1285
frequency: 200 kHz
field: H field
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 60 dB' in the listing
status: ground
source: lp-chomerics-1285
where: Shielding Effectiveness table, first row
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1285, 500 MHz E field
value: 110
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1285
frequency: 5.00e+8 Hz (500 MHz)
field: E field
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 110 dB' in the listing
status: ground
source: lp-chomerics-1285
where: Shielding Effectiveness table, row at 5.00e+8 Hz
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1285, 100 MHz E field
value: 115
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1285
frequency: 1.00e+8 Hz (100 MHz)
field: E field
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 115 dB' in the listing
status: ground
source: lp-chomerics-1285
where: Shielding Effectiveness table, row at 1.00e+8 Hz
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1285, 2 GHz plane wave
value: 105
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1285
frequency: 2.00e+9 Hz (2 GHz)
field: plane wave
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 105 dB' in the listing
status: ground
source: lp-chomerics-1285
where: Shielding Effectiveness table, row at 2.00e+9 Hz
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1285, 10 GHz plane wave
value: 100
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1285
frequency: 1.00e+10 Hz (10 GHz)
field: plane wave
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 100 dB' in the listing
status: ground
source: lp-chomerics-1285
where: Shielding Effectiveness table, row at 1.00e+10 Hz
- benchmark: heat_aged_volume_resistivity
label: Volume resistivity after heat ageing, CHO-SEAL 1285
value: 0.01
bound: upper
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1285
test: MIL-DTL-83528 Para. 4.6.15
exposure: not printed on the page
method: Maximum printed as '<0.01 ohm-cm' in the Descriptive Properties table
status: ground
source: lp-chomerics-1285
where: Descriptive Properties table, Heat Aging row
- benchmark: vibration_volume_resistivity
label: Volume resistivity after vibration, CHO-SEAL 1285
value: 0.008
bound: upper
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1285
test: MIL-DTL-83528 Para. 4.6.13
timing: after vibration
method: Maximum printed as '<0.008 ohm-cm'
status: ground
source: lp-chomerics-1285
where: Descriptive Properties table, Vibration Resistance, After row
- benchmark: vibration_volume_resistivity
label: Volume resistivity during vibration, CHO-SEAL 1285
value: 0.012
bound: upper
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1285
test: MIL-DTL-83528 Para. 4.6.13
timing: during vibration
method: Maximum printed as '<0.012 ohm-cm'
status: ground
source: lp-chomerics-1285
where: Descriptive Properties table, Vibration Resistance, During row
- benchmark: emp_survivability
label: EMP survivability, CHO-SEAL 1285
value: 0.9
bound: lower
unit: kA/in
scope: material
conditions:
product: CHO-SEAL 1285
test_method: not printed on the page
method: Minimum printed as '>0.9 kA / in'
status: ground
source: lp-chomerics-1285
where: Descriptive Properties table, EMP Survivability row
- benchmark: density
label: Specific gravity, CHO-SEAL 1287 (fluorosilicone binder)
value: 1.75
value_high: 2.25
bound: range
unit: g/cc
scope: material
conditions:
product: CHO-SEAL 1287
temperature: not printed on the page
method: Range printed as specific gravity with test standard ASTM D792
status: ground
source: lp-chomerics-1287
where: Physical Properties table, Specific Gravity row
- benchmark: hardness_shore_a
label: Hardness, Shore A, CHO-SEAL 1287
value: 63
value_high: 77
bound: range
unit: Shore A
scope: material
conditions:
product: CHO-SEAL 1287
scale: Shore A
method: Range printed with test method ASTM D2240
status: ground
source: lp-chomerics-1287
where: Mechanical Properties table, Hardness, Shore A row
- benchmark: ultimate_tensile_strength
label: Tensile strength at break, CHO-SEAL 1287
value: 1.24
bound: lower
unit: MPa
scope: material
conditions:
product: CHO-SEAL 1287
printed_as: 1.24 MPa or more (180 psi or more)
test: ASTM D412
method: Minimum printed with test method ASTM D412
status: ground
source: lp-chomerics-1287
where: Mechanical Properties table, Tensile Strength at Break row
- benchmark: elongation
label: Elongation at break, CHO-SEAL 1287
value: 60
value_high: 260
bound: range
unit: '%'
scope: material
conditions:
product: CHO-SEAL 1287
test: ASTM D412
method: Range printed with test method ASTM D412
status: ground
source: lp-chomerics-1287
where: Mechanical Properties table, Elongation at Break row
- benchmark: tear_strength
label: Tear strength, CHO-SEAL 1287
value: 6.13
unit: kN/m
scope: material
conditions:
product: CHO-SEAL 1287
printed_alongside: 35.0 pli
method: Typical value printed with test method ASTM D624
status: ground
source: lp-chomerics-1287
where: Mechanical Properties table, Tear Strength row
- benchmark: compression_set
label: Compression set, CHO-SEAL 1287
value: 30
bound: upper
unit: '%'
scope: material
conditions:
product: CHO-SEAL 1287
temperature: 100 °C
time: 252000 sec (70.0 hours as printed at 212 °F)
test: ASTM D395 Method B
method: Maximum printed with test method ASTM D395 Method B
status: ground
source: lp-chomerics-1287
where: Mechanical Properties table, Compression Set rows
- benchmark: max_service_temp
label: Maximum service temperature in air, CHO-SEAL 1287
value: 200
unit: °C
scope: material
conditions:
product: CHO-SEAL 1287
environment: air
method: Value printed; no test method given on the page
status: ground
source: lp-chomerics-1287
where: Thermal Properties table, Maximum Service Temperature, Air row
- benchmark: min_service_temp
label: Minimum service temperature in air, CHO-SEAL 1287
value: -55
unit: °C
scope: material
conditions:
product: CHO-SEAL 1287
environment: air
test: Flex TR10; ASTM D1329
method: Value printed with test method Flex TR10; ASTM D1329
status: ground
source: lp-chomerics-1287
where: Thermal Properties table, Minimum Service Temperature, Air row
- benchmark: electrical_resistivity
label: Volume resistivity, CHO-SEAL 1287
value: 0.012
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1287
state: without pressure-sensitive adhesive
test: MIL-DTL-83528
method: Value printed with the test named in the conditions
status: ground
source: lp-chomerics-1287
where: Electrical Properties table, Volume Resistivity row (first)
- benchmark: electrical_resistivity
label: Volume resistivity after tensile set, CHO-SEAL 1287
value: 0.015
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1287
state: post tensile set
test: MIL-DTL-83528 Para. 4.6.9 as printed
method: Value printed for the post-tensile-set condition; the page prints the standard as MIL-G-83528
status: ground
note: The page prints the standard reference as MIL-G-83528 in this row and MIL-DTL-83528 elsewhere.
source: lp-chomerics-1287
where: Electrical Properties table, Volume Resistivity row (second)
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1287, 200 kHz H field
value: 55
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1287
frequency: 200 kHz
field: H field
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 55 dB' in the listing
status: ground
source: lp-chomerics-1287
where: Shielding Effectiveness table, first row
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1287, 500 MHz E field
value: 100
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1287
frequency: 5.00e+8 Hz (500 MHz)
field: E field
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 100 dB' in the listing
status: ground
source: lp-chomerics-1287
where: Shielding Effectiveness table, row at 5.00e+8 Hz
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1287, 100 MHz E field
value: 110
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1287
frequency: 1.00e+8 Hz (100 MHz)
field: E field
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 110 dB' in the listing
status: ground
source: lp-chomerics-1287
where: Shielding Effectiveness table, row at 1.00e+8 Hz
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1287, 2 GHz plane wave
value: 95
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1287
frequency: 2.00e+9 Hz (2 GHz)
field: plane wave
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 95 dB' in the listing
status: ground
source: lp-chomerics-1287
where: Shielding Effectiveness table, row at 2.00e+9 Hz
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1287, 10 GHz plane wave
value: 90
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1287
frequency: 1.00e+10 Hz (10 GHz)
field: plane wave
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 90 dB' in the listing
status: ground
source: lp-chomerics-1287
where: Shielding Effectiveness table, row at 1.00e+10 Hz
- benchmark: shielding_effectiveness
label: Shielding effectiveness, CHO-SEAL 1287, 40 GHz plane wave
value: 75
bound: lower
unit: dB
scope: material
conditions:
product: CHO-SEAL 1287
frequency: 4.00e+10 Hz (40 GHz)
field: plane wave
standard: MIL-DTL-83528 Para. 4.6.12
method: Minimum printed as '>= 75 dB' in the listing
status: ground
source: lp-chomerics-1287
where: Shielding Effectiveness table, row at 4.00e+10 Hz
- benchmark: heat_aged_volume_resistivity
label: Volume resistivity after heat ageing, CHO-SEAL 1287
value: 0.015
bound: upper
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1287
test: MIL-DTL-83528 Para. 4.6.15
exposure: not printed on the page
method: Maximum printed as '<0.015 ohm-cm'
status: ground
source: lp-chomerics-1287
where: Descriptive Properties table, Heat Aging row
- benchmark: vibration_volume_resistivity
label: Volume resistivity after vibration, CHO-SEAL 1287
value: 0.012
bound: upper
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1287
test: MIL-DTL-83528 Para. 4.6.13
timing: after vibration
method: Maximum printed as '<0.012 ohm-cm'
status: ground
source: lp-chomerics-1287
where: Descriptive Properties table, Vibration Resistance, After row
- benchmark: vibration_volume_resistivity
label: Volume resistivity during vibration, CHO-SEAL 1287
value: 0.015
bound: upper
unit: ohm-cm
scope: material
conditions:
product: CHO-SEAL 1287
test: MIL-DTL-83528 Para. 4.6.13
timing: during vibration
method: Maximum printed as '<0.015 ohm-cm'
status: ground
source: lp-chomerics-1287
where: Descriptive Properties table, Vibration Resistance, During row
- benchmark: emp_survivability
label: EMP survivability, CHO-SEAL 1287
value: 0.9
bound: lower
unit: kA/in
scope: material
conditions:
product: CHO-SEAL 1287
test: MIL-DTL-83528 Para. 4.6.16
method: Minimum printed as '>0.9 kA / in' with the test paragraph named on the page
status: ground
source: lp-chomerics-1287
where: Descriptive Properties table, EMP Survivability row
corrosion:
- environment: Silver/aluminium filler in contact with aluminium housings (galvanic exposure)
headline: Silver/aluminium fillers pair well with aluminium housings and reduce galvanic risk, according to a Modus Advanced guide on space-qualified EMI gaskets.
effect: The guide's filler table rates silver/aluminium as good with aluminium housings, and its galvanic section says the filler reduces galvanic risk. It also says plating the housing with nickel or tin improves galvanic compatibility. No corrosion test on CHO-SEAL 1285 or 1287 was read.
rating: low
conditions:
basis: general vendor guidance, no test condition, exposure time or product named
housing: aluminium
source: modus-emi-guide
where: Filler Comparison table; Galvanic Compatibility section; Designing for Manufacturability section
- environment: Thermal cycling combined with galvanic exposure over a mission
headline: The Modus guide says thermal cycling and galvanic effects together can reduce shielding by several dB over a mission.
effect: The guide states that the combination of thermal cycling and galvanic effects can reduce shielding effectiveness by several dB over the life of a mission, and that wrong filler and housing pairings can increase contact resistance over time. The guide gives no dB figure or time for this loss.
rating: moderate
conditions:
basis: vendor statement, no mission duration or dB figure given
product: silver/aluminium filled gaskets in general
source: modus-emi-guide
where: Thermal Cycling section; Galvanic Compatibility section
- environment: Heat ageing at the MIL-DTL-83528 test condition
headline: After heat ageing, the listed volume resistivity stays below 0.01 ohm-cm for CHO-SEAL 1285 and below 0.015 ohm-cm for CHO-SEAL 1287.
effect: The Descriptive Properties tables of both Chomerics listings print a heat-ageing resistivity limit under MIL-DTL-83528 Para. 4.6.15. The exposure temperature and time are not printed on the pages, so the limit cannot be tied to a service life.
rating: low
conditions:
basis: maximum limits as printed; exposure temperature and time not printed
standard: MIL-DTL-83528 Para. 4.6.15
source: lp-chomerics-1285
where: Descriptive Properties table, Heat Aging row (1285); the 1287 page gives the 1287 row
- environment: Corrosion resistance claim on the CHO-SEAL 1285 listing
headline: The CHO-SEAL 1285 listing describes the material as having improved corrosion resistance but gives no test figure for it.
effect: The listing's Material Notes say 'Conductive Elastomer with Improved Corrosion Resistance'. The page does not name the comparison material, the test or the result, so the claim is recorded as printed and not rated.
rating: unknown
conditions:
basis: manufacturer claim as printed on a reseller listing
comparison: not stated
source: lp-chomerics-1285
where: Material Notes
risks:
hazards:
- text: 'Silver, as the plating on the filler particles (bare metal, powder or nano form): PubChem''s EU entries give ''Very toxic to aquatic life with long lasting effects'' and ''Very toxic to aquatic life'' with signal word ''Warning'' and the environmental hazard pictogram. Japanese NITE entries list ''May cause an allergic skin reaction'' and ''Causes eye irritation'' with signal word ''Danger''. These are GHS data for the bare metal, not for the gasket.'
ghs:
- H410
- H400
- H317
- H320
source: pubchem-silver
where: Safety and Hazards, GHS Classification (CID 23954)
- text: 'Aluminium, as the base metal of the filler particles (powder form): PubChem''s ECHA aggregate and most EU entries give ''In contact with water releases flammable gas'' with signal word ''Danger'' and the flammable pictogram. Stabilised aluminium powder is listed as ''Flammable solid'', and a pyrophoric powder entry as ''Catches fire spontaneously if exposed to air''. Japanese NITE-CMC entries add ''Causes damage to organs'' and ''Causes damage to organs through prolonged or repeated exposure''. These are GHS data for the bare powder, not for the gasket.'
ghs:
- H261
- H228
- H250
- H370
- H372
source: pubchem-aluminium
where: Safety and Hazards, GHS Classification (CID 5359268)
failure_risks:
- mode: Galvanic corrosion at the gasket-to-housing interface
trigger: Silver/aluminium filler in contact with a housing that is not plated or otherwise matched, in a humid or thermally cycled environment
consequence: The Modus guide says wrong filler and housing pairings can lead to increased contact resistance over time, which reduces shielding.
severity: moderate
source: modus-emi-guide
where: Galvanic Compatibility section
- mode: Shielding loss from thermal cycling over a mission
trigger: Repeated thermal cycling of a gasket seam over the life of a mission
consequence: The guide says the combined effects can reduce shielding effectiveness by several dB over the life of a mission. No dB value or time is given.
severity: moderate
source: modus-emi-guide
where: Thermal Cycling section
side_effects: []
handling: []
mitigations:
- text: Plate aluminium housings with nickel or tin to improve galvanic compatibility, as the Modus guide recommends for silver/aluminium gaskets.
source: modus-emi-guide
where: Designing for Manufacturability section
uses:
- application: electronics-and-chips
device: EMI gasket on enclosure flanges and covers in military electronics (MIL-DTL-83528 scope)
example: The MIL-DTL-83528 specification covers conductive elastomeric shielding gaskets that give low interface resistance between enclosure flanges or covers and provide environmental sealing. CHO-SEAL 1285 is listed as a Military-Aerospace Type B material to that specification.
source: everyspec-mil-83528
where: Scope summary; CHO-SEAL 1285 page, Grade and Type fields
- application: electronics-and-chips
device: EMI gasket for satellite electronics enclosures (vendor guidance, no flight result read)
example: A Modus Advanced guide on space-qualified EMI gaskets for satellite shielding discusses silver/aluminium fillers for this use. The guide gives no flight result for CHO-SEAL 1285 or 1287.
source: modus-emi-guide
where: Page title; FAQ heading 'Which conductive filler is best for satellite applications?'
supply:
- subject: Silver (filler metal)
abundance: Not read in this run. The USGS silver chapter was read for production, reserves and recycling only.
producers:
- country: Mexico
share_percent: 24.2
year: 2025
- country: Peru
share_percent: 13.8
year: 2025
- country: China
share_percent: 13.1
year: 2025
- country: Bolivia
share_percent: 5.8
year: 2025
- country: Chile
share_percent: 5.4
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals
listed: true
recycling: 'USGS: about 1,000 tons of silver was recovered from new and old scrap in the United States in 2025, about 11% of apparent consumption.'
substitutes:
- 'USGS: aluminum and rhodium may replace silver in mirrors and reflecting surfaces. The chapter names no substitute for silver in conductive elastomers.'
source: usgs-mcs2026-silver
where: 'Domestic Production and Use; Recycling; World Mine Production and Reserves table (2025e: Mexico 6,300, Peru 3,600, China 3,400, Bolivia 1,500, Chile 1,400 of a 26,000 world total); Substitutes. Shares calculated by Space Mushroom against the printed world total.'
- subject: Aluminium (filler base metal)
abundance: Not read in this run.
producers:
- country: China
share_percent: 60.8
year: 2025
- country: India
share_percent: 5.7
year: 2025
- country: Russia
share_percent: 5.3
year: 2025
- country: Canada
share_percent: 4.5
year: 2025
- country: United Arab Emirates
share_percent: 3.6
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals
listed: true
recycling: 'USGS: about 3.6 million tons of aluminum was recovered from purchased scrap in the United States in 2025, equivalent to about 28% of apparent consumption from old scrap.'
substitutes:
- 'USGS: copper can replace aluminum in electrical and heat-exchange applications.'
source: usgs-mcs2026-aluminum
where: 'World Smelter Production and Capacity table (2025e: China 45,000 of a 74,000 world total, India 4,200, Russia 3,900, Canada 3,300, United Arab Emirates 2,700); Recycling; Substitutes. Shares calculated by Space Mushroom against the printed world total (rounded). Smelter output, not mine output.'
note: The USGS table is smelter production of primary aluminium; it is not bauxite mine production.
documents:
- title: Parker Chomerics CHO-SEAL 1285 listing (lookpolymers.com, data attributed to Chomerics)
type: datasheet
url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1285-Conductive-Elastomer.php
- title: Parker Chomerics CHO-SEAL 1287 listing (lookpolymers.com, data attributed to Chomerics)
type: datasheet
url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1287-Conductive-Elastomer.php
- title: MIL-DTL-83528E, Gaskets, Electrically Conductive Elastomeric, Shielding (EverySpec summary page)
type: standard
url: https://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-83528E_52081/
year: 2012
- title: 'USGS Mineral Commodity Summaries 2026: Silver'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Aluminum'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
year: 2026
- title: PubChem compound record for Silver (CID 23954), GHS Classification
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/23954
- title: PubChem compound record for Aluminum (CID 5359268), GHS Classification
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/5359268
gaps:
- 'No Parker Chomerics datasheet or product page could be opened in this run: the Parker selector guide, the NASA outgassing PDF, the CHO-TM-TP09 test procedure and the ph.parker.com product pages returned HTTP 403, and the Mouser listing timed out. All CHO-SEAL values come from two reseller pages that state the information is provided by Chomerics.'
- Outgassing (ASTM E595 total mass loss and CVCM) for CHO-SEAL 1285 or 1287 was not read on a fetched page. A search summary mentioned Parker outgassing figures, but they were not opened and are not recorded here.
- No flight, space-environment or vacuum result for CHO-SEAL 1285 or 1287 was read. The space use in the uses section is vendor guidance, not a flight record.
- The MIL-DTL-83528 per-type plane-wave shielding table was not read. The EverySpec page shows only the scope and revision list, and the PDF returned HTTP 404.
- The revision of MIL-DTL-83528 that governs CHO-SEAL 1285 and 1287 is not confirmed. The EverySpec page shows Rev. E dated 2012 with later revisions F and G listed; the revision letter cited by each Chomerics listing is not printed.
- No safety data sheet for CHO-SEAL 1285 or 1287 was read. The hazards entries use PubChem GHS data for the constituent silver and aluminium metals in powder form, not for the gasket, so the gasket's own hazard classification is not recorded. A search returned SDSs only for other silver-aluminium or nickel-graphite products, which were not used.
- Binder and filler mass shares, and the composition of the silver-plated aluminium particles, are not printed in any source read.
- Thermal conductivity is printed for CHO-SEAL 1285 only; the CHO-SEAL 1287 listing prints none.
- Chemical resistance, salt-fog or humidity corrosion data, and galvanic test data for CHO-SEAL 1285 or 1287 were not found in any source read. The corrosion-resistance claim on the 1285 listing has no figure.
- Hardness (Shore A), tear strength, compression set, heat-ageing and vibration resistivity, and EMP survivability are not in the properties canon; they use short snake_case names (hardness_shore_a, tear_strength, compression_set, heat_aged_volume_resistivity, vibration_volume_resistivity, emp_survivability).
- Shielding effectiveness values are the listing's minimum values for two grades, not measured data on a stated gasket size or seam. The conditions for the seam, compression and mounting are not printed.
- Abundance (crustal) of silver and aluminium and the EU critical raw materials list were not read in this run.
- No comparison with other shielding profiles in this collection was made; their values were not read for this profile.
sources:
lp-chomerics-1285:
title: Parker Chomerics CHO-SEAL 1285 Conductive Elastomer (product listing on lookpolymers.com; information provided by Chomerics)
id: CHO-SEAL 1285; Military-Aerospace Grade B; MIL-DTL-83528 Type B
url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1285-Conductive-Elastomer.php
year: 2026
kind: web
license: reseller listing, linked not reproduced
lp-chomerics-1287:
title: Parker Chomerics CHO-SEAL 1287 Conductive Elastomer (product listing on lookpolymers.com; information provided by Chomerics)
id: CHO-SEAL 1287; Military-Aerospace Type D; MIL-DTL-83528 Type D
url: https://www.lookpolymers.com/polymer_Parker-Chomerics-CHO-SEAL-1287-Conductive-Elastomer.php
year: 2026
kind: web
license: reseller listing, linked not reproduced
everyspec-mil-83528:
title: MIL-DTL-83528E, Gaskets, Electrically Conductive Elastomeric, Shielding (summary page)
id: MIL-DTL-83528E, dated 13-AUG-2012 (Rev. E listed as 08-2012)
url: https://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-83528E_52081/
year: 2012
kind: standard
license: standard summary, linked not reproduced
ssp-mil-83528-guide:
title: 'Military Gaskets for EMI Shielding: What are MIL-DTL-83528 and QPL 83528? (Specialty Silicone Products)'
id: SSP web article on MIL-DTL-83528 sections A, B, C, D and K
url: https://sspinc.com/?p=11006
kind: web
license: vendor article, linked not reproduced
modus-emi-guide:
title: 'Space-Qualified EMI Gasket Selection: A Material Guide for Satellite Shielding (Modus Advanced)'
id: Modus Advanced blog guide
url: https://www.modusadvanced.com/resources/blog/space-qualified-emi-gasket-selection-a-material-guide-for-satellite-shielding-1
kind: web
license: vendor article, linked not reproduced
usgs-mcs2026-silver:
title: Mineral Commodity Summaries 2026, Silver
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mcs2026-aluminum:
title: Mineral Commodity Summaries 2026, Aluminum
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-crit2025:
title: About the 2025 List of Critical Minerals (USGS, final list)
id: Final 2025 List of Critical Minerals, November 2025
url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
year: 2025
kind: web
license: public domain (USGS)
pubchem-silver:
title: PubChem compound record for Silver (CID 23954), GHS Classification
id: PubChem CID 23954
url: https://pubchem.ncbi.nlm.nih.gov/compound/23954
kind: database
license: public domain (NCBI PubChem), linked not reproduced
pubchem-aluminium:
title: PubChem compound record for Aluminum (CID 5359268), GHS Classification
id: PubChem CID 5359268
url: https://pubchem.ncbi.nlm.nih.gov/compound/5359268
kind: database
license: public domain (NCBI PubChem), linked not reproduced
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 40
unreachable: 5
caveats: 5
note: 'Read by an AI assistant on 2026-11-01. All CHO-SEAL values come from two reseller listings that attribute the data to Chomerics; the Parker pages, the NASA outgassing PDF and the MIL-DTL-83528 PDF could not be opened. Unreachable: Parker selector guide, Parker product page, Parker CHO-TM-TP09 procedure, Parker NASA outgassing PDF (all HTTP 403), and the MIL-DTL-83528 PDF (HTTP 404). Caveats: values are typical or minimum listing figures; the shielding minima are for one test set-up; the 1287 resistivity row cites MIL-G-83528; the specific gravity is not a density.'
story:
recipe:
line: 'CHO-SEAL gaskets are a conductive elastomer: a cured silicone or fluorosilicone binder filled with silver-plated aluminium particles, printed as Ag/Al. The binder gives the rubber sealing and resilience; the filler gives the electrical conductivity. Shares of binder and filler are not printed in any source read.'
parts:
- name: Silicone or fluorosilicone elastomer binder
role: The rubber matrix. It gives the gasket its hardness, elongation and sealing; CHO-SEAL 1285 uses a silicone binder and CHO-SEAL 1287 a fluorosilicone binder.
share_note: Mass share not printed in the sources read
- name: Silver-plated aluminium particles (Ag/Al)
role: The conductive filler. Silver on aluminium particles provides the electrical path that gives the shielding and the low volume resistivity.
share_note: Mass share not printed in the sources read
risk_groups:
- title: For people
lead: No safety data sheet for CHO-SEAL 1285 or 1287 was read in this run, so their own hazard classification is not recorded. PubChem GHS data for the constituent silver and aluminium metals is in the hazards section.
level: 0
verdict: Not checked
points:
- label: Hazard data
line: The sources read give no hazard classification for these two gasket grades. Read the supplier's safety data sheet for the exact part before handling.
- title: If it fails
lead: 'The failure routes in the sources read are electrical: loss of shielding and contact resistance over time.'
points:
- label: Galvanic and thermal
line: The Modus guide says wrong filler and housing pairings can raise contact resistance over time, and that thermal cycling plus galvanic effects can reduce shielding by several dB over a mission. It gives no time or dB figure.
why: Conductive elastomer EMI gaskets seal an enclosure seam and carry its shielding current across the joint. CHO-SEAL 1285 and CHO-SEAL 1287 are Parker Chomerics silver-aluminium filled gaskets built to the MIL-DTL-83528 specification. The 1285 has a silicone binder and is listed as Type B, with at least 100 dB of plane-wave shielding at 10 GHz. The 1287 has a fluorosilicone binder and is listed as Type D, with at least 90 dB at 10 GHz. The choice between them depends on the binder and the shielding frequency needed.
uses:
- where: Military and aerospace electronics
line: The MIL-DTL-83528 specification covers electrically conductive elastomeric shielding gaskets that give low interface resistance between enclosure flanges or covers and also provide environmental sealing. CHO-SEAL 1285 is listed as a Type B material to that specification.
- where: Satellite electronics (vendor guidance only)
line: A Modus Advanced guide on space-qualified EMI gaskets for satellite shielding discusses silver/aluminium fillers for this use. The guide does not give a flight result for these two grades.
can_do:
- label: Shielding
benchmark: shielding_effectiveness
value: At least 100 dB at 10 GHz
line: Per the CHO-SEAL 1285 listing, the minimum plane-wave shielding effectiveness is 100 dB at 10 GHz (1.00e+10 Hz) and 110 dB at 500 MHz for the E field. The 1287 listing gives 90 dB at 10 GHz and 100 dB at 500 MHz for the E field.
- label: Conductivity
benchmark: electrical_resistivity
value: 0.0080 ohm-cm
line: The 1285 listing prints a volume resistivity of 0.0080 ohm-cm without pressure-sensitive adhesive, and 0.015 ohm-cm after tensile set. The 1287 listing prints 0.012 ohm-cm and 0.015 ohm-cm.
- label: Temperature
benchmark: max_service_temp
value: 200 °C in air
line: Both listings print a maximum service temperature in air of 200 °C. The 1285 minimum is -65 °C and the 1287 minimum is -55 °C, both per the Flex TR10 and ASTM D1329 test named on the pages.
compare: 'This profile compares two grades from one manufacturer rather than other shielding materials. CHO-SEAL 1285 (silicone, Type B) lists at least 100 dB at 10 GHz and 0.0080 ohm-cm volume resistivity. CHO-SEAL 1287 (fluorosilicone, Type D) lists at least 90 dB at 10 GHz and 0.012 ohm-cm. The two grades are not interchangeable: the binder changes the shielding minima and the resistivity as printed.'
compare_rows:
- label: Specific gravity
benchmark: density
- label: Volume resistivity
benchmark: electrical_resistivity
- label: Shielding effectiveness
benchmark: shielding_effectiveness
handling:
- No handling source was read for CHO-SEAL 1285 or 1287. Check the supplier's safety data sheet for the exact part.
- The listed service range is -65 °C to 200 °C in air for CHO-SEAL 1285 and -55 °C to 200 °C for CHO-SEAL 1287.
- Specify the grade by name, since the binder and the minimum temperature differ between 1285 and 1287.
good_for:
- Enclosure seams that need a conductive gasket to MIL-DTL-83528. CHO-SEAL 1285 is listed as Type B with at least 100 dB at 10 GHz.
- 'Seams that must stay conductive through vibration: volume resistivity after vibration is printed as below 0.008 ohm-cm for CHO-SEAL 1285.'
watch_out:
- 'Galvanic pairing: the Modus guide says the filler suits aluminium housings but the pairing still needs plating or matching to avoid contact-resistance rise over time.'
- 'Thermal cycling: the guide says shielding can fall by several dB over a mission. No time or dB figure is given.'
- 'Outgassing and flight data: none were read for these two grades, so their suitability for vacuum use is not established by these sources.'
verdict: 'CHO-SEAL 1285 and 1287 are MIL-DTL-83528 silver-aluminium gaskets with printed shielding minima and volume resistivity. The sources read give listing values only: no Parker datasheet, outgassing, hazard or flight data could be checked in this run.'
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
Updated