Apiezon L ultra-high vacuum grease Apiezon L
Petroleum hydrocarbon grease with no single chemical formula: silicone-free and halogen-free, with a complex hydrocarbon structure and very high molecular weight · CAS 12678-02-3 (Agar Scientific SDS); 8009-03-8 (M&I Materials SDS). The two safety data sheets disagree on the CAS number.
Also known as Apiezon L, APIEZON GREASE L
Apiezon L is a silicone-free, halogen-free hydrocarbon grease sold for sealing and lubricating ultra-high-vacuum systems.
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.
Recommended use range
10 to 30 °C
Weight
0.896 g/cm3
Melting
42 to 52 °C
Thermal conductivity
0.216 W/m°C
Recipe, share of the weight
- - not statedPetroleum hydrocarbon base (composition not published)
Best for
Sealing ground joints and lubricating parts in ultra-high-vacuum systems near room temperature, where a very low vapour pressure matters
Weakest at
Heat: the manufacturer recommends 10 to 30 °C in use, and the grease melts between 42 and 52 °C
Risk at a glance
- People Low. Mixed classification
- If it fails Moderate. Vacuum performance loss after exposure to air and vapour
- Corrosion Moderate. The grease absorbs water and hydrocarbon vapour, which the manufacturer says degrades its vapour pressure performance.
Quick facts: Apiezon L
| Property | Value | Basis |
|---|---|---|
| Density | 0.9 g/cm³ | 1 sourced value |
| Thermal conductivity | 0.19 to 0.22 W/(m·K) | 2 sourced values across conditions |
| Thermal expansion (CTE) | 760 ppm/K | 1 sourced value |
| Melting point | 42 to 52 °C | 1 sourced value |
| Maximum service temperature | 30 °C | 1 sourced value |
What is the density of Apiezon L ultra-high vacuum grease?
Apiezon L ultra-high vacuum grease has a density of 0.9 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the thermal conductivity of Apiezon L ultra-high vacuum grease?
Apiezon L ultra-high vacuum grease has a thermal conductivity of 0.19 to 0.22 W/(m·K). 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 coefficient of thermal expansion of Apiezon L ultra-high vacuum grease?
Apiezon L ultra-high vacuum grease has a coefficient of thermal expansion of 760 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Apiezon L ultra-high vacuum grease?
Apiezon L ultra-high vacuum grease has a melting point of 42 to 52 °C. The source and test conditions are listed in the properties table on this page.
What is the maximum service temperature of Apiezon L ultra-high vacuum grease?
Apiezon L ultra-high vacuum grease has a maximum service temperature of 30 °C. The source and test conditions are listed in the properties table on this page.
What are the other names and codes for Apiezon L ultra-high vacuum grease?
Apiezon L ultra-high vacuum grease is also written as Apiezon L, APIEZON GREASE L. Each code is printed in the source listed beside it in the designations table.
What is Apiezon L ultra-high vacuum grease used for?
Uses recorded in the sources include Ground-glass joints and sealing surfaces in ultra-high-vacuum systems; Vacuum test rigs and instrument work for space hardware; Fastener-installation lubricant on LDEF experiment A0180 (polymer matrix composite study).
Why it exists
Apiezon L is a silicone-free, halogen-free hydrocarbon grease used to seal and lubricate ultra-high-vacuum systems. The manufacturer and the M&I Materials safety data sheet both print its vapour pressure as 7 x 10-11 Torr at 20 °C, which is the low figure that makes it useful in vacuum. It is a semi-solid at room temperature, with a density of 0.896 g/cm3 at 20 °C, and it melts between 42 and 52 °C. Its recommended use is between 10 and 30 °C, and above that range it softens and runs.
Where it's used
Ground joints in vacuum systems
The Delta Microscopies page says the grease may be used on all ground joints in a vacuum system, but not on stopcocks. The M&I Materials SDS gives the product use as sealing and lubricating grease for ultra high vacuum applications.
Space and test work
The Agar Scientific page names ESA, NASA and NATO as users of the grease. No flight outgassing result for Type L was read in this run.
Recipe
Petroleum hydrocarbon grease with no single chemical formula: silicone-free and halogen-free, with a complex hydrocarbon structure and very high molecular weight
Apiezon L is a petroleum hydrocarbon grease with no single chemical formula. The manufacturer's page says it is silicone-free and halogen-free, the Agar page calls it a complex hydrocarbon structure with very high molecular weight, and the Delta Microscopies page says it contains no additives. The sources give no percentage composition and no manufacturing steps.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Petroleum hydrocarbon base (composition not published) - | not stated | The whole material. No percentage composition or base oil name is printed in any source read. |
Weight shares are as printed in the sources.
What it can do
Recommended use range
10 to 30 °C
measured
The manufacturer recommends use generally between 10 and 30 °C.
Weight
0.896 g/cm3
measured
The density at 20 °C is 0.896 g/cm3 in the Agar Scientific SDS, and the M&I Materials SDS prints a relative density of 0.896 at 20°C.
Melting
42 to 52 °C
measured
The melting point is printed as a range of 42 to 52 °C in the Agar SDS.
Thermal conductivity
0.216 W/m°C
measured
The Delta Microscopies table prints thermal conductivity 0.216 W/m°C for Type L, with no temperature given.
How it compares
The manufacturer's radiation statement is the only comparison this profile has. The page says esters, silicones and halogenated paraffins decompose at radiation levels of 0.1 MGy or less, and that Apiezon L was tested to 1 MGy with 4 MeV electrons. The page does not print a stiffness or mass-loss figure for the Apiezon L test, so the comparison is qualitative.
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 | Apiezon L |
|---|---|
| Thermal behavior and safety | |
| Melting point range, Apiezon L (Agar Scientific SDS) | 42 to 52 °C2 |
| Thermal conductivity, Apiezon L | 0.216 W/m°C5 |
| Fusion peak temperature, Apiezon L | 32 °C13 |
| Latent heat of fusion, Apiezon L | 15.1 cal/g14 |
| Thermal conductivity at 20 °C, Apiezon L (manufacturer datasheet, 2026) | 0.194 W/m°C19 |
| Physical and electrical | |
| Density at 20 °C, Apiezon L (Agar Scientific SDS) | 0.896 g/cm³1 |
| Temperature behavior | |
| Auto-ignition temperature, Apiezon L (M&I Materials SDS) | > 250 °C12 |
| Other measurements | |
| Recommended lower operating temperature, Apiezon L | 10 °C3 |
| Recommended upper operating temperature, Apiezon L | 30 °C4 |
| Coefficient of expansion per °C, Apiezon L | 7.6×10^-4 1/°C6 |
| Permittivity, Apiezon L | 2.3 -7 |
| Loss tangent, Apiezon L | < 1×10^-4 -8 |
| Electric strength, Apiezon L (as printed in V) | 730 V9 |
| Flash point, Apiezon L (Agar Scientific SDS) | > 200 °C10 |
| Initial boiling point, Apiezon L (M&I Materials SDS) | > 500 °C11 |
| Lubricity, four-ball test, Apiezon L | 150 kg15 |
| Total mass loss (TML), Apiezon L, ASTM E 595 | < 1 %16 |
| Collected volatile condensable materials (CVCM), Apiezon L, ASTM E 595 | < 0.1 %17 |
| Dropping point, Apiezon L (manufacturer datasheet, 2026) | 50 to 70 °C18 |
| Viscosity of molten grease at 50 °C, Apiezon L | 766 cSt20 |
| Viscosity of molten grease at 100 °C, Apiezon L | 62.3 cSt21 |
Why choose it, and why not
Good for
- Sealing ground joints in ultra-high-vacuum systems near room temperature.
- Low vapour pressure: 7 x 10-11 Torr at 20 °C, as printed by the manufacturer.
- Radiation tolerance: the manufacturer says 1 MGy of 4 MeV electrons stiffens it only slightly, which the page contrasts with 0.1 MGy for other grease types.
Watch out for
- Heat: the grease is recommended only from 10 to 30 °C in use, and it melts between 42 and 52 °C.
- No flight outgassing result for Type L was read, and the NASA database entries did not load in this run.
- The two SDS sheets disagree on CAS number and on hazard class, so check the sheet from your own supplier.
- The vapour pressure figure differs between sources (7 x 10-11 Torr, 8 x 10-11 torr and 10 hPa), so use the figure that matches your supplier's sheet.
Apiezon L is a silicone-free hydrocarbon grease with a vapour pressure of 7 x 10-11 Torr at 20 °C and a density of 0.896 g/cm3 at 20 °C. It is recommended for 10 to 30 °C and melts between 42 and 52 °C, so it suits cool ultra-high-vacuum joints but not warm ones. This profile has no flight outgassing number for Type L, and the two safety data sheets disagree on CAS number and hazard class.
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 | Apiezon L, APIEZON GREASE L |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density at 20 °C, Apiezon L (Agar Scientific SDS) | Value printed in the physical and chemical properties section of a safety data sheet | grade Apiezon L, article AGB7270temperature 20 °C | The M&I Materials SDS (January 2014) prints relative density 0.896 at 20°C, and the Delta Microscopies table prints 0.896 for Type L, so the sources agree. |
| 2 | Melting point range, Apiezon L (Agar Scientific SDS) | Range printed in the physical and chemical properties section of a safety data sheet | method in source ASTM D 566 is named for the melting point in the Delta Microscopies table; the SDS gives the range without a method | — |
| 3 | Recommended lower operating temperature, Apiezon L | Range printed on the manufacturer's product page; the page calls it a general recommendation, not a hard limit | basis generally between 10 to 30 °C, the recommended ambient rangegrade Apiezon L | — |
| 4 | Recommended upper operating temperature, Apiezon L | Range printed on the manufacturer's product page; the page calls it a general recommendation, not a hard limit | basis generally between 10 to 30 °C, the recommended ambient rangegrade Apiezon L | — |
| 5 | Thermal conductivity, Apiezon L | Value printed in the typical property table of a product page that reproduces the manufacturer's data | grade Type L (column L of the Typical Property table)temperature not stated | — |
| 6 | Coefficient of expansion per °C, Apiezon L | Value printed in the typical property table of a product page that reproduces the manufacturer's data | grade Type L (column L of the Typical Property table)temperature range 20 to 30 °C | — |
| 7 | Permittivity, Apiezon L | Value printed in the typical property table of a product page that reproduces the manufacturer's data | grade Type L (column L of the Typical Property table)frequency not statedtemperature not stated | — |
| 8 | Loss tangent, Apiezon L | Value printed as a bound in the typical property table of a product page that reproduces the manufacturer's data | grade Type L (column L of the Typical Property table)frequency not stated | — |
| 9 | Electric strength, Apiezon L (as printed in V) | Value printed in the typical property table of a product page that reproduces the manufacturer's data | thickness not statedunit in source V | The table prints the value in volts with no test thickness, so it cannot be compared with dielectric strength given in kV/mm. |
| 10 | Flash point, Apiezon L (Agar Scientific SDS) | Value printed in the physical and chemical properties section of a safety data sheet | method in source not stated in the SDS | The M&I Materials SDS prints the flash point as >200°C. |
| 11 | Initial boiling point, Apiezon L (M&I Materials SDS) | Value printed in the physical and chemical properties section of a safety data sheet | basis initial boiling point and boiling range as printed | The Agar Scientific SDS prints 500 °C without the greater-than sign. |
| 12 | Auto-ignition temperature, Apiezon L (M&I Materials SDS) | Value printed in the physical and chemical properties section of a safety data sheet | basis as printed in the SDS | The Agar Scientific SDS prints Ignition temperature 250 °C in the same section, without the greater-than sign. |
| 13 | Fusion peak temperature, Apiezon L | Value printed in the typical property table of a product page that reproduces the manufacturer's data; method not named | grade Type L (column L of the Typical Property table)basis not stated | — |
| 14 | Latent heat of fusion, Apiezon L | Value printed in the typical property table of a product page that reproduces the manufacturer's data; method not named | grade Type L (column L of the Typical Property table)basis not stated | — |
| 15 | Lubricity, four-ball test, Apiezon L | Value printed in the typical property table of a product page that reproduces the manufacturer's data | test ASTM D 2763 / IP 239, named in the tablegrade Type L (column L of the Typical Property table) | The table prints the figure as 150 with unit Kg under the four-ball lubricity row. It does not state the test load or the wear measure used. |
| 16 | Total mass loss (TML), Apiezon L, ASTM E 595 | Value printed as a bound in the Typical Properties table of the 2026 manufacturer datasheet | grade Type L (column L of the Typical Properties table)test ASTM E 595 (printed as ASTM .E 595-93(2003)e1) | — |
| 17 | Collected volatile condensable materials (CVCM), Apiezon L, ASTM E 595 | Value printed as a bound in the Typical Properties table of the 2026 manufacturer datasheet | grade Type L (column L of the Typical Properties table)test ASTM E 595 (printed as ASTM .E 595-93(2003)e1) | — |
| 18 | Dropping point, Apiezon L (manufacturer datasheet, 2026) | Range printed in the Typical Properties table of the 2026 manufacturer datasheet | grade Type L (column L of the Typical Properties table)method in source ASTM.D 566 | The 2005 Idealvac copy of the datasheet prints 42 to 52 °C for Type L, and the Agar and M&I safety data sheets print a melting range of 42 to 52 °C. The two datasheet editions disagree, and both are recorded. |
| 19 | Thermal conductivity at 20 °C, Apiezon L (manufacturer datasheet, 2026) | Value printed in the Typical Properties table of the 2026 manufacturer datasheet | grade Type L (column L of the Typical Properties table)temperature 20 °C | The Delta Microscopies table in this profile prints 0.216 W/m°C for Type L with no temperature. The 2026 and 2005 datasheets both print 0.194 W/m°C at 20 °C, so the two values are recorded side by side. |
| 20 | Viscosity of molten grease at 50 °C, Apiezon L | Value printed in the Typical Properties table of the 2026 manufacturer datasheet | grade Type L (column L of the Typical Properties table)temperature 50 °C | — |
| 21 | Viscosity of molten grease at 100 °C, Apiezon L | Value printed in the Typical Properties table of the 2026 manufacturer datasheet | grade Type L (column L of the Typical Properties table)temperature 100 °C | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Radiation (4 MeV electrons) | low | The manufacturer's page says Apiezon L was irradiated with 4 MeV electrons to 1 MGy, and it contrasts this with 0.1 MGy for other grease types.1 |
| Water and hydrocarbon vapour | moderate | The grease absorbs water and hydrocarbon vapour, which the manufacturer says degrades its vapour pressure performance.2 |
| Warm joints in use | moderate | The grease is not recommended for joints that run above 30 °C in use.3 |
| High temperature | moderate | The Agar Scientific safety data sheet lists temperatures above 120 °C as a condition to avoid.4 |
| Oxygen and liquid-oxygen service | moderate | The manufacturer does not recommend Apiezon L for oxygen service because of a small risk of auto-ignition.5 |
| Elastomer seals | moderate | Apiezon L is listed as compatible with Viton, silicone, nitrile above 30 % nitrile, nylon, polyurethane, polyethylene and polypropylene.6 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Radiation (4 MeV electrons) | The page says esters, silicones and halogenated paraffins decompose at radiation levels of 0.1 MGy or less. It gives no mass-loss, viscosity or stiffness number for the Apiezon L test. | dose 1 MGyparticle 4 MeV electronsresult qualitative only, no number printed |
| 2 | Water and hydrocarbon vapour | The manufacturer says the tube should be re-capped immediately after use and kept away from volatile vapours, because the grease absorbs water and hydrocarbon vapours. The page does not give a number for the loss of performance. | exposure open or uncapped tube, volatile vapours present |
| 3 | Warm joints in use | Delta Microscopies says the grease is not recommended for joints where temperatures exceed 30 °C in use. The melting range is 42 to 52 °C, so a joint above 30 °C is also below the melting point. | limit 30 °C in usebasis manufacturer's recommendation |
| 4 | High temperature | The SDS lists temperature above 120 °C and strong oxidising agents as conditions to avoid, and says no dangerous decomposition products are known. | limit above 120 °Cincompatible strong oxidising agents |
| 5 | Oxygen and liquid-oxygen service | The page says hydrocarbon greases are not recommended for oxygen or liquid-oxygen use because of the small risk of auto-ignition. It says only PFPE 501 is listed as suitable, and PFPE 501 is a different product. | service oxygen and liquid oxygen |
| 6 | Elastomer seals | The manufacturer lists these as compatible. It lists EPDM, EPR, butyl rubber and PVC seals as not compatible. | basis manufacturer compatibility statement, no test data |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The two safety data sheets disagree on hazard class, and both are recorded here. Both list high temperature and strong oxidising agents as conditions to avoid.
- Hazard class
- The Agar Scientific SDS of 2019 classifies the grease as harmful if swallowed or in contact with skin (H302 and H312, signal word Warning). The M&I Materials SDS of 2014 says it is not classified under CLP, and gives an oral and dermal LD50 above 2000 mg/kg.
- Skin and eyes
- Both sheets say skin and eye contact are the most likely routes. The M&I sheet says repeated or prolonged skin contact may cause dry skin or irritation.
If it fails
These routes come from the manufacturer's pages and the SDS sheets. None of them is a measured test result for this grease.
- Vacuum loss
- The manufacturer says the grease absorbs water and hydrocarbon vapours, which degrades its vapour pressure performance. The page gives no number for the loss.
- Warm joints
- Delta Microscopies says the grease is not recommended for joints above 30 °C in use. It melts between 42 and 52 °C.
- Oxygen service
- The manufacturer does not recommend hydrocarbon greases in oxygen service because of a small risk of auto-ignition.
Handling and storage
- Keep the tube sealed
- Re-cap the tube immediately after use and keep it away from volatile vapours, since the grease absorbs water and hydrocarbon vapours.
- Cleaning
- Wipe off excess with a lint-free cloth. Warm soapy water or toluene or xylene removes residue. Alcohols and ketones are not suitable.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Vacuum performance loss after exposure to air and vapourmoderate severity | Tube left open after use, or exposure to water and hydrocarbon vapoursThe manufacturer says the grease absorbs water and hydrocarbon vapours, which degrades its vapour pressure performance. No number is given for the loss. |
| Softening and melting in warm jointsmoderate severity | Joint temperature above the recommended 10 to 30 °C range, and temperatures near the melting range of 42 to 52 °CThe grease liquefies above its melting point and returns to its normal state on cooling, provided the temperature rise was not excessive (manufacturer). |
| Decomposition or reaction at high temperaturemoderate severity | Temperatures above 120 °C, or contact with strong oxidising agentsThe SDS lists these as conditions to avoid and says no dangerous decomposition products are known. It gives no decomposition onset temperature. |
| Auto-ignition risk in oxygen servicemoderate severity | Use in oxygen or liquid-oxygen systemsThe manufacturer says hydrocarbon greases carry a small risk of auto-ignition in oxygen service. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Seals and O-rings in the vacuum system | Incompatible with EPDM, EPR, butyl rubber and PVC seals, so the seal material must be checked before use. |
Handling and storage
- The manufacturer says the grease may be used on all ground joints in a vacuum system, but not on stopcocks.
- Wipe off excess with a soft, lint-free cloth. Residues can be removed with warm soapy water or an aromatic hydrocarbon solvent such as toluene or xylene. Limonene is suggested as a less harmful option. The page says alcohols and ketones cannot be used for cleaning.
- Keep the tube re-capped after use, away from volatile vapours, because the grease absorbs water and hydrocarbon vapours.
- Spilt grease is a slip hazard. Do not let it enter sewers or surface or ground water, and clean up spills promptly.
Supply and geography
How common the raw materials are and where they come from.
Apiezon L grease (manufacturer and distributors)
- Top producers
- United Kingdom
- Recycling
- The M&I Materials SDS says product and packaging must be disposed of under local and national rules. It says the product may be incinerated, and unused product may be returned for reclamation.
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: apiezon-l-grease
spore_version: 0.2
family: vacuum-greases
name: Apiezon L ultra-high vacuum grease
abbreviation: Apiezon L
role: sealing and lubricating grease for ultra-high vacuum
category: tribology
type: greases
summary: |
Apiezon L is a silicone-free, halogen-free hydrocarbon grease sold for sealing and lubricating ultra-high-vacuum systems. The manufacturer's page and the M&I Materials safety data sheet both print its vapour pressure as 7 x 10-11 Torr at 20 °C. Its density is 0.896 g/cm3 at 20 °C and it melts between 42 and 52 °C, per the Agar Scientific safety data sheet of 2019. The manufacturer recommends use between 10 and 30 °C, and no outgassing value for Type L was printed in the table read for this profile.
best_for: Sealing ground joints and lubricating parts in ultra-high-vacuum systems near room temperature, where a very low vapour pressure matters
weakest_at: 'Heat: the manufacturer recommends 10 to 30 °C in use, and the grease melts between 42 and 52 °C'
identity:
formula: 'Petroleum hydrocarbon grease with no single chemical formula: silicone-free and halogen-free, with a complex hydrocarbon structure and very high molecular weight'
cas: 12678-02-3 (Agar Scientific SDS); 8009-03-8 (M&I Materials SDS). The two safety data sheets disagree on the CAS number.
source: oxinst-sds-l
where: Section 1.1 Product identifier, CAS number 12678-02-3; the M&I Materials SDS, section 1.1, gives 8009-03-8
designations:
- system: Trade name
code: Apiezon L
source: apiezon-com-l
where: Product page title and product name
- system: Trade name
code: APIEZON GREASE L
source: oxinst-sds-l
where: Section 1.1 Trade name
tags:
environments: []
stresses:
- vacuum-and-outgassing
- total-radiation-dose
applications:
- mechanisms
- in-space-manufacturing
properties:
- benchmark: density
label: Density at 20 °C, Apiezon L (Agar Scientific SDS)
value: 0.896
unit: g/cm3
scope: material
conditions:
grade: Apiezon L, article AGB7270
temperature: 20 °C
method: Value printed in the physical and chemical properties section of a safety data sheet
status: ground
note: The M&I Materials SDS (January 2014) prints relative density 0.896 at 20°C, and the Delta Microscopies table prints 0.896 for Type L, so the sources agree.
source: oxinst-sds-l
where: Section 9.1, row Density at 20 °C
- benchmark: melting_point
label: Melting point range, Apiezon L (Agar Scientific SDS)
value: 42
value_high: 52
bound: range
unit: °C
scope: material
conditions:
method_in_source: ASTM D 566 is named for the melting point in the Delta Microscopies table; the SDS gives the range without a method
method: Range printed in the physical and chemical properties section of a safety data sheet
status: ground
source: oxinst-sds-l
where: Section 9.1, row Melting point/freezing point
- benchmark: min_service_temp
label: Recommended lower operating temperature, Apiezon L
value: 10
unit: °C
scope: material
conditions:
basis: generally between 10 to 30 °C, the recommended ambient range
grade: Apiezon L
method: Range printed on the manufacturer's product page; the page calls it a general recommendation, not a hard limit
status: ground
source: apiezon-com-l
where: '''What is Apiezon L grease?'' section, first paragraph'
- benchmark: max_service_temp
label: Recommended upper operating temperature, Apiezon L
value: 30
unit: °C
scope: material
conditions:
basis: generally between 10 to 30 °C, the recommended ambient range
grade: Apiezon L
method: Range printed on the manufacturer's product page; the page calls it a general recommendation, not a hard limit
status: ground
source: apiezon-com-l
where: '''What is Apiezon L grease?'' section, first paragraph'
- benchmark: thermal_conductivity
label: Thermal conductivity, Apiezon L
value: 0.216
unit: W/m°C
scope: material
conditions:
grade: Type L (column L of the Typical Property table)
temperature: not stated
method: Value printed in the typical property table of a product page that reproduces the manufacturer's data
status: ground
source: delta-apiezon-l
where: Typical Property table, row Thermal conductivity, w/m°C, column L
- benchmark: cte
label: Coefficient of expansion per °C, Apiezon L
value: 0.00076
unit: 1/°C
scope: material
conditions:
grade: Type L (column L of the Typical Property table)
temperature_range: 20 to 30 °C
method: Value printed in the typical property table of a product page that reproduces the manufacturer's data
status: ground
source: delta-apiezon-l
where: Typical Property table, row Coefficient of expansion per °C (20-30°C), column L
- benchmark: dielectric_constant
label: Permittivity, Apiezon L
value: 2.3
unit: '-'
scope: material
conditions:
grade: Type L (column L of the Typical Property table)
frequency: not stated
temperature: not stated
method: Value printed in the typical property table of a product page that reproduces the manufacturer's data
status: ground
source: delta-apiezon-l
where: Typical Property table, row Permittivity, column L
- benchmark: dissipation_factor
label: Loss tangent, Apiezon L
value: 0.0001
bound: upper
unit: '-'
scope: material
conditions:
grade: Type L (column L of the Typical Property table)
frequency: not stated
method: Value printed as a bound in the typical property table of a product page that reproduces the manufacturer's data
status: ground
source: delta-apiezon-l
where: Typical Property table, row Loss tangent, column L, printed as <0.0001
- benchmark: dielectric_strength
label: Electric strength, Apiezon L (as printed in V)
value: 730
unit: V
scope: material
conditions:
thickness: not stated
unit_in_source: V
method: Value printed in the typical property table of a product page that reproduces the manufacturer's data
status: ground
note: The table prints the value in volts with no test thickness, so it cannot be compared with dielectric strength given in kV/mm.
source: delta-apiezon-l
where: Typical Property table, row Electric strength (V), column L
- benchmark: flash_point
label: Flash point, Apiezon L (Agar Scientific SDS)
value: 200
bound: lower
unit: °C
scope: material
conditions:
method_in_source: not stated in the SDS
method: Value printed in the physical and chemical properties section of a safety data sheet
status: ground
note: The M&I Materials SDS prints the flash point as >200°C.
source: oxinst-sds-l
where: Section 9.1, row Flash point
- benchmark: boiling_point
label: Initial boiling point, Apiezon L (M&I Materials SDS)
value: 500
bound: lower
unit: °C
scope: material
conditions:
basis: initial boiling point and boiling range as printed
method: Value printed in the physical and chemical properties section of a safety data sheet
status: ground
note: The Agar Scientific SDS prints 500 °C without the greater-than sign.
source: mi-sds-l
where: Section 9.1, row Initial boiling point and boiling range, printed as >500°C
- benchmark: auto_ignition_temperature
label: Auto-ignition temperature, Apiezon L (M&I Materials SDS)
value: 250
bound: lower
unit: °C
scope: material
conditions:
basis: as printed in the SDS
method: Value printed in the physical and chemical properties section of a safety data sheet
status: ground
note: The Agar Scientific SDS prints Ignition temperature 250 °C in the same section, without the greater-than sign.
source: mi-sds-l
where: Section 9.1, row Auto-ignition temperature, printed as >250°C
- benchmark: fusion_peak_temperature
label: Fusion peak temperature, Apiezon L
value: 32
unit: °C
scope: material
conditions:
grade: Type L (column L of the Typical Property table)
basis: not stated
method: Value printed in the typical property table of a product page that reproduces the manufacturer's data; method not named
status: ground
source: delta-apiezon-l
where: Typical Property table, row Fusion peak (°C), column L
- benchmark: latent_heat_of_fusion
label: Latent heat of fusion, Apiezon L
value: 15.1
unit: cal/g
scope: material
conditions:
grade: Type L (column L of the Typical Property table)
basis: not stated
method: Value printed in the typical property table of a product page that reproduces the manufacturer's data; method not named
status: ground
source: delta-apiezon-l
where: Typical Property table, row Latent heat of fusion (cal/g), column L
- benchmark: four_ball_lubricity_load
label: Lubricity, four-ball test, Apiezon L
value: 150
unit: kg
scope: material
conditions:
test: ASTM D 2763 / IP 239, named in the table
grade: Type L (column L of the Typical Property table)
method: Value printed in the typical property table of a product page that reproduces the manufacturer's data
status: ground
note: The table prints the figure as 150 with unit Kg under the four-ball lubricity row. It does not state the test load or the wear measure used.
source: delta-apiezon-l
where: Typical Property table, row Lubricity, 4 Ball Test (ASTM D 2763 / IP 239, Kg), column L
- benchmark: total_mass_loss
label: Total mass loss (TML), Apiezon L, ASTM E 595
value: 1
bound: upper
unit: '%'
scope: material
conditions:
grade: Type L (column L of the Typical Properties table)
test: ASTM E 595 (printed as ASTM .E 595-93(2003)e1)
method: Value printed as a bound in the Typical Properties table of the 2026 manufacturer datasheet
status: ground
source: apiezon-datasheet-2026
where: Typical Properties table, row Outgassing characteristics, TML, column L, printed as <1%
- benchmark: cvcm
label: Collected volatile condensable materials (CVCM), Apiezon L, ASTM E 595
value: 0.1
bound: upper
unit: '%'
scope: material
conditions:
grade: Type L (column L of the Typical Properties table)
test: ASTM E 595 (printed as ASTM .E 595-93(2003)e1)
method: Value printed as a bound in the Typical Properties table of the 2026 manufacturer datasheet
status: ground
source: apiezon-datasheet-2026
where: Typical Properties table, row Outgassing characteristics, CVCM, column L, printed as <0.1%
- benchmark: dropping_point
label: Dropping point, Apiezon L (manufacturer datasheet, 2026)
value: 50
value_high: 70
bound: range
unit: °C
scope: material
conditions:
grade: Type L (column L of the Typical Properties table)
method_in_source: ASTM.D 566
method: Range printed in the Typical Properties table of the 2026 manufacturer datasheet
status: ground
note: The 2005 Idealvac copy of the datasheet prints 42 to 52 °C for Type L, and the Agar and M&I safety data sheets print a melting range of 42 to 52 °C. The two datasheet editions disagree, and both are recorded.
source: apiezon-datasheet-2026
where: Typical Properties table, row Dropping point - ASTM.D 566, column L
- benchmark: thermal_conductivity
label: Thermal conductivity at 20 °C, Apiezon L (manufacturer datasheet, 2026)
value: 0.194
unit: W/m°C
scope: material
conditions:
grade: Type L (column L of the Typical Properties table)
temperature: 20 °C
method: Value printed in the Typical Properties table of the 2026 manufacturer datasheet
status: ground
note: The Delta Microscopies table in this profile prints 0.216 W/m°C for Type L with no temperature. The 2026 and 2005 datasheets both print 0.194 W/m°C at 20 °C, so the two values are recorded side by side.
source: apiezon-datasheet-2026
where: Typical Properties table, row Thermal conductivity @ 20°C, W/m°C, column L
- benchmark: molten_viscosity
label: Viscosity of molten grease at 50 °C, Apiezon L
value: 766
unit: cSt
scope: material
conditions:
grade: Type L (column L of the Typical Properties table)
temperature: 50 °C
method: Value printed in the Typical Properties table of the 2026 manufacturer datasheet
status: ground
source: apiezon-datasheet-2026
where: Typical Properties table, row Viscosity of molten grease, cSt @ 50°C / 122°F, column L
- benchmark: molten_viscosity
label: Viscosity of molten grease at 100 °C, Apiezon L
value: 62.3
unit: cSt
scope: material
conditions:
grade: Type L (column L of the Typical Properties table)
temperature: 100 °C
method: Value printed in the Typical Properties table of the 2026 manufacturer datasheet
status: ground
source: apiezon-datasheet-2026
where: Typical Properties table, row Viscosity of molten grease, cSt @ 100°C / 212°F, column L
checked_values: 21
corrosion:
- environment: Radiation (4 MeV electrons)
headline: The manufacturer's page says Apiezon L was irradiated with 4 MeV electrons to 1 MGy, and it contrasts this with 0.1 MGy for other grease types.
effect: The page says esters, silicones and halogenated paraffins decompose at radiation levels of 0.1 MGy or less. It gives no mass-loss, viscosity or stiffness number for the Apiezon L test.
rating: low
conditions:
dose: 1 MGy
particle: 4 MeV electrons
result: qualitative only, no number printed
source: apiezon-com-l
where: '''When should Apiezon L grease be used?'' section'
- environment: Water and hydrocarbon vapour
headline: The grease absorbs water and hydrocarbon vapour, which the manufacturer says degrades its vapour pressure performance.
effect: The manufacturer says the tube should be re-capped immediately after use and kept away from volatile vapours, because the grease absorbs water and hydrocarbon vapours. The page does not give a number for the loss of performance.
rating: moderate
conditions:
exposure: open or uncapped tube, volatile vapours present
source: apiezon-com-l
where: Storage statement
- environment: Warm joints in use
headline: The grease is not recommended for joints that run above 30 °C in use.
effect: Delta Microscopies says the grease is not recommended for joints where temperatures exceed 30 °C in use. The melting range is 42 to 52 °C, so a joint above 30 °C is also below the melting point.
rating: moderate
conditions:
limit: 30 °C in use
basis: manufacturer's recommendation
source: delta-apiezon-l
where: Product description text
- environment: High temperature
headline: The Agar Scientific safety data sheet lists temperatures above 120 °C as a condition to avoid.
effect: The SDS lists temperature above 120 °C and strong oxidising agents as conditions to avoid, and says no dangerous decomposition products are known.
rating: moderate
conditions:
limit: above 120 °C
incompatible: strong oxidising agents
source: oxinst-sds-l
where: Section 10.4 and 10.5
- environment: Oxygen and liquid-oxygen service
headline: The manufacturer does not recommend Apiezon L for oxygen service because of a small risk of auto-ignition.
effect: The page says hydrocarbon greases are not recommended for oxygen or liquid-oxygen use because of the small risk of auto-ignition. It says only PFPE 501 is listed as suitable, and PFPE 501 is a different product.
rating: moderate
conditions:
service: oxygen and liquid oxygen
source: apiezon-com-l
where: Oxygen/LOX use statement
- environment: Elastomer seals
headline: Apiezon L is listed as compatible with Viton, silicone, nitrile above 30 % nitrile, nylon, polyurethane, polyethylene and polypropylene.
effect: The manufacturer lists these as compatible. It lists EPDM, EPR, butyl rubber and PVC seals as not compatible.
rating: moderate
conditions:
basis: manufacturer compatibility statement, no test data
source: apiezon-com-l
where: Elastomer compatibility statement
risks:
hazards:
- text: 'Agar Scientific SDS (printed 27.02.2019): classified under CLP with GHS07, signal word Warning, and H302 harmful if swallowed and H312 harmful in contact with skin.'
ghs:
- H302
- H312
source: oxinst-sds-l
where: Sections 2.1 and 2.2
- text: 'M&I Materials SDS (January 2014): the product is not classified under CLP and has no signal word. Acute oral and dermal toxicity are both LD50 above 2000 mg/kg.'
ghs: []
source: mi-sds-l
where: Sections 2.1, 2.2 and 11.1
- text: 'M&I Materials UK SDS (version 15, March 2026): the substance is not classified under GB-CLP, and the classification criteria for acute toxicity are not met.'
ghs: []
source: apiezon-sds-uk-2026
where: Section 2.1 (GB-CLP classification) and Section 11.1 (acute toxicity)
failure_risks:
- mode: Vacuum performance loss after exposure to air and vapour
trigger: Tube left open after use, or exposure to water and hydrocarbon vapours
consequence: The manufacturer says the grease absorbs water and hydrocarbon vapours, which degrades its vapour pressure performance. No number is given for the loss.
severity: moderate
source: apiezon-com-l
where: Storage statement
- mode: Softening and melting in warm joints
trigger: Joint temperature above the recommended 10 to 30 °C range, and temperatures near the melting range of 42 to 52 °C
consequence: The grease liquefies above its melting point and returns to its normal state on cooling, provided the temperature rise was not excessive (manufacturer).
severity: moderate
source: apiezon-com-l
where: Heating statement
- mode: Decomposition or reaction at high temperature
trigger: Temperatures above 120 °C, or contact with strong oxidising agents
consequence: The SDS lists these as conditions to avoid and says no dangerous decomposition products are known. It gives no decomposition onset temperature.
severity: moderate
source: oxinst-sds-l
where: Sections 10.4 to 10.6
- mode: Auto-ignition risk in oxygen service
trigger: Use in oxygen or liquid-oxygen systems
consequence: The manufacturer says hydrocarbon greases carry a small risk of auto-ignition in oxygen service.
severity: moderate
source: apiezon-com-l
where: Oxygen/LOX use statement
side_effects:
- text: Incompatible with EPDM, EPR, butyl rubber and PVC seals, so the seal material must be checked before use.
affects: Seals and O-rings in the vacuum system
source: apiezon-com-l
where: Elastomer compatibility statement
handling:
- text: The manufacturer says the grease may be used on all ground joints in a vacuum system, but not on stopcocks.
source: delta-apiezon-l
where: Product description and handling text
- text: Wipe off excess with a soft, lint-free cloth. Residues can be removed with warm soapy water or an aromatic hydrocarbon solvent such as toluene or xylene. Limonene is suggested as a less harmful option. The page says alcohols and ketones cannot be used for cleaning.
source: apiezon-com-l
where: Cleaning statement
- text: Keep the tube re-capped after use, away from volatile vapours, because the grease absorbs water and hydrocarbon vapours.
source: apiezon-com-l
where: Storage statement
- text: Spilt grease is a slip hazard. Do not let it enter sewers or surface or ground water, and clean up spills promptly.
source: oxinst-sds-l
where: Sections 6.1 and 6.2
mitigations: []
uses:
- application: mechanisms
device: Ground-glass joints and sealing surfaces in ultra-high-vacuum systems
example: The Delta Microscopies page says the grease may be used on all ground joints in a vacuum system, not on stopcocks. The M&I Materials SDS gives its product use as sealing and lubricating grease for ultra high vacuum applications.
source: delta-apiezon-l
where: Product description and handling text; M&I SDS section 1.2
- application: in-space-manufacturing
device: Vacuum test rigs and instrument work for space hardware
example: The Agar Scientific page names ESA, NASA and NATO as users. This profile read no flight or test report that confirms the grease in orbit.
source: agar-apiezon-l
where: Product description text naming ESA, NASA and NATO as users
- application: mechanisms
device: Fastener-installation lubricant on LDEF experiment A0180 (polymer matrix composite study)
example: The 1993 NASA report on LDEF says Apiezon L was used as a fastener-installation lubricant on experiment A0180, and that it was not examined after retrieval.
source: nasa-ldef-lubricants-1993
where: Apiezon L paragraph in the LDEF lubricant survey, the entry for experiment A0180
supply:
- subject: Apiezon L grease (manufacturer and distributors)
producers:
- name: M&I Materials Ltd (manufacturer named on apiezon.com and in the datasheet)
country: United Kingdom
critical_lists: []
recycling: The M&I Materials SDS says product and packaging must be disposed of under local and national rules. It says the product may be incinerated, and unused product may be returned for reclamation.
substitutes: []
source: mi-sds-l
where: Section 13.1 Waste treatment methods; supplier named in section 1.3 (M&I Materials Ltd, Manchester, UK)
documents:
- title: Apiezon L Grease, safety data sheet, M&I Materials Ltd, January 2014 (copy hosted by Purdue University)
type: sds
url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/Apiezon%20L.pdf
year: 2014
- title: APIEZON GREASE L, safety data sheet, Agar Scientific Ltd, printed 27.02.2019 (copy hosted by Oxford Instruments)
type: sds
url: https://estore.oxinst.com/INTERSHOP/static/WFS/Oxinst-GB-Site/-/Oxinst/en_GB/PDFS/MSDS_-_APIEZON_GREASE_L_(GB).pdf
year: 2019
- title: Apiezon Grease Type L, Delta Microscopies product page
type: datasheet
url: https://www.deltamicroscopies.com/?p=235116
- title: Apiezon L grease, manufacturer product page (apiezon.com)
type: datasheet
url: https://apiezon.com/products/vacuum-greases/apiezon-l-grease/
- title: Apiezon L grease, Agar Scientific product page
type: datasheet
url: https://www.agarscientific.com/apiezon-l-grease
- title: APIEZON L, M & N Ultra High and High Vacuum Greases, manufacturer datasheet (September 2026)
type: datasheet
url: https://apiezon.com/wp-content/uploads/2023/10/Apiezon_L_M_and_N_Ultra_High_and_High_Vacuum_Greases_Datasheet.pdf
year: 2026
- title: Apiezon L Grease, safety data sheet, M&I Materials Ltd, version 15, March 2026
type: sds
url: https://apiezon.com/wp-content/uploads/2022/12/Apiezon_L_Grease_SDS_UK.pdf
year: 2026
- title: Apiezon L, M and N Ultra High and High Vacuum Greases datasheet (Idealvac copy, August 2005)
type: datasheet
url: https://www.idealvac.com/files/manuals/Apiezonlmn_tds.pdf
year: 2005
- title: Identification and Evaluation of Lubricants, Adhesives, and Seals used on LDEF (NASA NTRS 19930001400)
type: report
url: https://ntrs.nasa.gov/api/citations/19930001400/downloads/19930001400.pdf
year: 1993
gaps:
- 'Outgassing (TML and CVCM, ASTM E595): the 2026 manufacturer datasheet prints TML <1% and CVCM <0.1% for Type L, and the 2005 Idealvac copy prints the same. The Delta Microscopies table prints ''/'' for Type L, so that reseller copy disagrees with the manufacturer. Both are noted; the manufacturer figures are recorded.'
- 'NASA outgassing database: the page read in this run did not load its entries (''Loading filtered data''), so no NASA entry for Apiezon L was confirmed or ruled out. No flight result for this grease was read.'
- Vapour pressure is not entered as a numeric property. The manufacturer page and the M&I Materials SDS both print 7 x 10-11 Torr at 20 °C, but verify-values could not match that printed form against a numeric value, so the property was removed rather than left unchecked. The Delta Microscopies description gives 8 x 10-11 torr and the Agar SDS gives 10 hPa; these disagree with the 7 x 10-11 Torr figure and are not reconciled.
- 'CAS number disagrees: 12678-02-3 (Agar Scientific SDS) and 8009-03-8 (M&I Materials SDS, 2014). The UK SDS of March 2026 prints 8009-03-8, the same as the 2014 sheet.'
- 'Hazard classification disagrees: H302 and H312 (Agar SDS, 2019) against not classified (M&I SDS, 2014, and UK SDS, March 2026). All three are recorded.'
- 'Dropping point: the 2026 manufacturer datasheet prints 50 to 70 °C for Type L (ASTM.D 566), and the 2005 Idealvac copy prints 42 to 52 °C. The two editions disagree; the 2026 range is recorded and the 2005 range is noted in its note. The melting range of 42 to 52 °C is a separate measurement.'
- 'Viscosity of the molten grease: the 2026 datasheet assigns 766 cSt at 50 °C and 62.3 cSt at 100 °C to the L column, so both are recorded. The 413 and 29.8 pair belongs to the M column.'
- 'Volume resistivity: the 2026 datasheet prints 1.2 x 10^16 Ω cm for Type L, and the Delta table prints it with the unit ''(cm)'' only. The value is printed in scientific notation, so it is not recorded.'
- Surface breakdown at flash-over (24 kV in the Delta table) has no test thickness or method. Not recorded.
- 'Thermal conductivity: the Delta table prints 0.216 W/m°C with no temperature, while the 2026 and 2005 datasheets print 0.194 W/m°C at 20 °C. Both are recorded side by side; they disagree and this is not resolved. No cryogenic value was found.'
- 'Lubricity method: the Delta table names ASTM D 2763 for the 150 kg four-ball value, while both manufacturer datasheets name ASTM D 2596. The 150 kg value is recorded with the Delta citation.'
- 'Radiation: only the 4 MeV electrons to 1 MGy test is described, qualitatively. No mass-loss, viscosity or stiffness number was printed.'
- 'Composition: no base oil name or percentage composition was printed on any page. The recipe has no atomic breakdown.'
- 'Supply: no producer shares or country data for a petroleum grease were found. The manufacturer is named as M&I Materials Ltd (Manchester, UK). USGS and critical-mineral lists were not checked because they do not apply to a hydrocarbon grease.'
- The EMS-Diasum product page and datasheet returned HTTP 403, and the ProSciTech product page returned HTTP 429 (rate limit). They were not read.
- No open peer-reviewed study of Apiezon L was found in the searches. The sources are manufacturer, distributor and SDS documents, plus one NASA report on LDEF (1993) that flew Apiezon L and did not examine it after retrieval. The profile has 9 sources.
- 'Non-canonical property names used: vapour_pressure, auto_ignition_temperature, fusion_peak_temperature, latent_heat_of_fusion, four_ball_lubricity_load, total_mass_loss, cvcm, dropping_point and molten_viscosity. These are not in spores/property-canon.yaml.'
- Ratings in the corrosion section (low, moderate) are a judgement from the wording of each source, not from a test standard.
sources:
delta-apiezon-l:
title: Apiezon Grease; Type L (Delta Microscopies product page, REF D6070), with Typical Property table
url: https://www.deltamicroscopies.com/?p=235116
kind: web
license: Retailer product page reproducing manufacturer data (cited, not reproduced)
apiezon-com-l:
title: Apiezon L grease, manufacturer product page (apiezon.com)
url: https://apiezon.com/products/vacuum-greases/apiezon-l-grease/
kind: web
license: Manufacturer product page (cited, not reproduced)
agar-apiezon-l:
title: Apiezon L grease, Agar Scientific product page
url: https://www.agarscientific.com/apiezon-l-grease
kind: web
license: Distributor product page (cited, not reproduced)
apiezon-datasheet-2026:
title: APIEZON L, M & N Ultra High and High Vacuum Greases, manufacturer datasheet (M&I Materials Ltd, September 2026)
url: https://apiezon.com/wp-content/uploads/2023/10/Apiezon_L_M_and_N_Ultra_High_and_High_Vacuum_Greases_Datasheet.pdf
kind: datasheet
year: 2026
license: Manufacturer datasheet (cited, not reproduced)
apiezon-sds-uk-2026:
title: Safety data sheet, Apiezon L Grease, M&I Materials Ltd, version 15, March 2026 (SDS reference 112032601)
url: https://apiezon.com/wp-content/uploads/2022/12/Apiezon_L_Grease_SDS_UK.pdf
kind: datasheet
year: 2026
license: Manufacturer safety data sheet (cited, not reproduced)
idealvac-apiezon-lmn-2005:
title: Apiezon L, M and N Ultra High and High Vacuum Greases, datasheet (Idealvac copy, August 2005)
url: https://www.idealvac.com/files/manuals/Apiezonlmn_tds.pdf
kind: datasheet
year: 2005
license: Reseller copy of the manufacturer datasheet (cited, not reproduced)
nasa-ldef-lubricants-1993:
title: Identification and Evaluation of Lubricants, Adhesives, and Seals used on LDEF, Bruce Keough, Boeing Aerospace (NASA NTRS 19930001400)
url: https://ntrs.nasa.gov/api/citations/19930001400/downloads/19930001400.pdf
kind: report
year: 1993
license: NASA technical report (cited, not reproduced)
oxinst-sds-l:
title: Safety data sheet, APIEZON GREASE L, Agar Scientific Ltd, printed 27.02.2019, version 1 (copy hosted by Oxford Instruments)
id: Article AGB7270; CAS 12678-02-3
url: https://estore.oxinst.com/INTERSHOP/static/WFS/Oxinst-GB-Site/-/Oxinst/en_GB/PDFS/MSDS_-_APIEZON_GREASE_L_(GB).pdf
year: 2019
kind: datasheet
license: Manufacturer or supplier safety data sheet (cited, not reproduced)
mi-sds-l:
title: Safety data sheet, Apiezon L Grease, M&I Materials Ltd, January 2014 (copy hosted by Purdue University)
id: CAS 8009-03-8
url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/Apiezon%20L.pdf
year: 2014
kind: datasheet
license: Manufacturer safety data sheet (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 21
unreachable: 3
caveats: 6
note: 'Values were read by an AI assistant on 2026-11-01 from the pages and PDFs named in each entry. The two safety data sheets were downloaded and text was extracted with pdftotext. Unreachable: EMS-Diasum (403), ProSciTech (429, rate limit) and the NASA outgassing database (entries did not load). Caveats: the vapour pressure, CAS number and hazard classification disagree across sources; the Type L outgassing values are not printed; the viscosity column is not assigned; the Delta Microscopies table is a reseller copy of manufacturer data; the corrosion ratings are a judgement.'
story:
risk_groups:
- title: For people
lead: The two safety data sheets disagree on hazard class, and both are recorded here. Both list high temperature and strong oxidising agents as conditions to avoid.
level: 1
verdict: Mixed classification
points:
- label: Hazard class
line: The Agar Scientific SDS of 2019 classifies the grease as harmful if swallowed or in contact with skin (H302 and H312, signal word Warning). The M&I Materials SDS of 2014 says it is not classified under CLP, and gives an oral and dermal LD50 above 2000 mg/kg.
- label: Skin and eyes
line: Both sheets say skin and eye contact are the most likely routes. The M&I sheet says repeated or prolonged skin contact may cause dry skin or irritation.
- title: If it fails
lead: These routes come from the manufacturer's pages and the SDS sheets. None of them is a measured test result for this grease.
points:
- label: Vacuum loss
line: The manufacturer says the grease absorbs water and hydrocarbon vapours, which degrades its vapour pressure performance. The page gives no number for the loss.
- label: Warm joints
line: Delta Microscopies says the grease is not recommended for joints above 30 °C in use. It melts between 42 and 52 °C.
- label: Oxygen service
line: The manufacturer does not recommend hydrocarbon greases in oxygen service because of a small risk of auto-ignition.
- title: Handling and storage
points:
- label: Keep the tube sealed
line: Re-cap the tube immediately after use and keep it away from volatile vapours, since the grease absorbs water and hydrocarbon vapours.
- label: Cleaning
line: Wipe off excess with a lint-free cloth. Warm soapy water or toluene or xylene removes residue. Alcohols and ketones are not suitable.
why: Apiezon L is a silicone-free, halogen-free hydrocarbon grease used to seal and lubricate ultra-high-vacuum systems. The manufacturer and the M&I Materials safety data sheet both print its vapour pressure as 7 x 10-11 Torr at 20 °C, which is the low figure that makes it useful in vacuum. It is a semi-solid at room temperature, with a density of 0.896 g/cm3 at 20 °C, and it melts between 42 and 52 °C. Its recommended use is between 10 and 30 °C, and above that range it softens and runs.
uses:
- where: Ground joints in vacuum systems
line: The Delta Microscopies page says the grease may be used on all ground joints in a vacuum system, but not on stopcocks. The M&I Materials SDS gives the product use as sealing and lubricating grease for ultra high vacuum applications.
- where: Space and test work
line: The Agar Scientific page names ESA, NASA and NATO as users of the grease. No flight outgassing result for Type L was read in this run.
can_do:
- label: Recommended use range
value: 10 to 30 °C
benchmark: min_service_temp
line: The manufacturer recommends use generally between 10 and 30 °C.
- label: Weight
value: 0.896 g/cm3
benchmark: density
line: The density at 20 °C is 0.896 g/cm3 in the Agar Scientific SDS, and the M&I Materials SDS prints a relative density of 0.896 at 20°C.
- label: Melting
value: 42 to 52 °C
benchmark: melting_point
line: The melting point is printed as a range of 42 to 52 °C in the Agar SDS.
- label: Thermal conductivity
value: 0.216 W/m°C
benchmark: thermal_conductivity
line: The Delta Microscopies table prints thermal conductivity 0.216 W/m°C for Type L, with no temperature given.
compare: The manufacturer's radiation statement is the only comparison this profile has. The page says esters, silicones and halogenated paraffins decompose at radiation levels of 0.1 MGy or less, and that Apiezon L was tested to 1 MGy with 4 MeV electrons. The page does not print a stiffness or mass-loss figure for the Apiezon L test, so the comparison is qualitative.
compare_rows:
- label: Density
benchmark: density
- label: Melting point
benchmark: melting_point
- label: Upper use temperature
benchmark: max_service_temp
handling:
- Re-cap the tube after each use, because the grease absorbs water and hydrocarbon vapours.
- Use only on joints below 30 °C in use, and check the seal material, since EPDM, EPR, butyl rubber and PVC are not compatible.
- Do not use it in oxygen or liquid-oxygen service.
good_for:
- Sealing ground joints in ultra-high-vacuum systems near room temperature.
- 'Low vapour pressure: 7 x 10-11 Torr at 20 °C, as printed by the manufacturer.'
- 'Radiation tolerance: the manufacturer says 1 MGy of 4 MeV electrons stiffens it only slightly, which the page contrasts with 0.1 MGy for other grease types.'
watch_out:
- 'Heat: the grease is recommended only from 10 to 30 °C in use, and it melts between 42 and 52 °C.'
- No flight outgassing result for Type L was read, and the NASA database entries did not load in this run.
- The two SDS sheets disagree on CAS number and on hazard class, so check the sheet from your own supplier.
- The vapour pressure figure differs between sources (7 x 10-11 Torr, 8 x 10-11 torr and 10 hPa), so use the figure that matches your supplier's sheet.
verdict: Apiezon L is a silicone-free hydrocarbon grease with a vapour pressure of 7 x 10-11 Torr at 20 °C and a density of 0.896 g/cm3 at 20 °C. It is recommended for 10 to 30 °C and melts between 42 and 52 °C, so it suits cool ultra-high-vacuum joints but not warm ones. This profile has no flight outgassing number for Type L, and the two safety data sheets disagree on CAS number and hazard class.
recipe:
line: Apiezon L is a petroleum hydrocarbon grease with no single chemical formula. The manufacturer's page says it is silicone-free and halogen-free, the Agar page calls it a complex hydrocarbon structure with very high molecular weight, and the Delta Microscopies page says it contains no additives. The sources give no percentage composition and no manufacturing steps.
parts:
- name: Petroleum hydrocarbon base (composition not published)
symbol: '-'
role: The whole material. No percentage composition or base oil name is printed in any source read.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
Updated