Chromate conversion coating Alodine 1200S (MIL-DTL-5541)
Mainly hydrated chromium(III) oxide with some chromium(VI) bound in it, grown on the aluminium surface as an amorphous film
Also known as Alodine 1200S, BONDERITE M-CR 1200S AERO
Chromate conversion coating is a thin film that a chromate bath grows on aluminium alloys.
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.
Corrosion barrier
0.25 to 1 µm
Paint base
Within 48 hours
Self-repair
Cr(VI) migrates
Process speed
15 s to 3 min
Heat limit
60 °C
Recipe, share of the weight
- Cr not statedChromium
- O not statedOxygen
- Al not statedAluminium
Best for
Corrosion protection and a paint base on aluminium structures, and low-resistance electrical contact in its Class 3 form
Weakest at
Hexavalent chemistry: NIOSH treats Cr(VI) compounds as potential occupational carcinogens, and unpainted parts must not go above 60 °C
Risk at a glance
- People Low. Hexavalent chromium is the concern
- If it fails Moderate. Loss of corrosion protection on unpainted parts above 60 °C
- Corrosion Moderate. Unpainted chromate coatings lose corrosion resistance above 60 °C.
Why it exists
Chromate conversion coating is a long-standing aluminium pre-treatment. It puts a thin film on the metal that protects it from corrosion and gives paint a base. Grilli describes the film as low in surface electrical resistance, which the thesis calls an important feature for the space industry. NASA PRC-5005 uses Class 3 for coatings where lower electrical resistance is required, and Class 1A for maximum corrosion protection. Type I, the hexavalent version, is recommended for most flight hardware.
Where it's used
Structures
Henkel lists its powder on Qualified Product List QPL-81706 for Class 1A and Class 3 coatings, bare or painted, to MIL-DTL-5541. NASA lets MIL-DTL-5541 coatings serve as a primer base or a temporary fabrication coating.
Electrical grounding
PRC-5005 names Class 3 for protection where lower electrical resistance is required. The sources opened give no numeric resistance value for it.
Paint and bonding preparation
The coating is a good base for paint primers and only a fair base for bonding. The standard bonding method removes it during surface preparation, and the primer or adhesive should go on within 48 hours.
Recipe
Mainly hydrated chromium(III) oxide with some chromium(VI) bound in it, grown on the aluminium surface as an amorphous film
Chromate conversion coating is a thin film formed on aluminium by reaction with an acidic chromate bath. The dry film is mostly chromium(III) oxide with very little aluminium oxide, and it holds some chromium(VI) within it (Wikipedia). Process: clean, rinse, deoxidise if the surface is heavily oxidised, rinse, treat, rinse, then dry (Henkel). The Henkel bath is acidic, at pH 1.3 to 1.8.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Chromium Cr | not stated | The film-forming metal. Chromium(VI) in the bath is reduced to chromium(III), which forms the hydrated oxide; some chromium(VI) stays bound and can migrate to defects. |
| Oxygen O | not stated | Bound to chromium in the oxide film. Chromium(III) oxide is the main constituent of the dry coating. |
| Aluminium Al | not stated | The substrate. Aluminium is oxidised as the chromium is reduced, and very little aluminium oxide remains in the final film (Wikipedia; Grilli 2010). |
Weight shares are as printed in the sources.
What it can do
Corrosion barrier
0.25 to 1 µm
One finisher gives the film thickness as 0.25 to 1 µm. Wikipedia gives 200 to 300 nm as the typical dry coating, and 200 to 1000 nm as the average for Alodine 1200s on aluminium.
Paint base
Within 48 hours
PRC-5005 says primer or adhesive must go on in less than 48 hours after the conversion treatment for adequate adhesion.
Self-repair
Cr(VI) migrates
Chromium(VI) in the film migrates to defects, where it can repassivate pits. Grilli notes that ageing and water loss may limit this action.
Process speed
15 s to 3 min
The Henkel sheet gives 15 seconds to 3 minutes of treatment time, at a bath temperature of 20 to 30 °C in the operation section.
Heat limit
60 °C
Unpainted hexavalent chromate parts should not exceed 60 °C (140 °F), according to NASA-STD-6012A section 4.6.2.
How it compares
Anodize, covered by the anodized aluminium profile, grows an oxide skin that the profile describes as electrically insulating. Chromate conversion coating is a thin chemical film and is chosen where lower electrical resistance is needed, as NASA PRC-5005 describes for Class 3. Type II coatings avoid hexavalent chromium, but PRC-5005 says Type I consistently outperforms Type II in corrosion tests, and Grilli reviews chromium-free alternatives for aluminium without giving a single replacement value. The table below compares film thickness, the heat limit for unpainted parts and the bath pH.
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 | Alodine 1200S (MIL-DTL-5541) |
|---|---|
| Lifetime and stability | |
| Shelf life of unopened powder | 48 months6 |
| Physical and electrical | |
| Coating thickness, typical dry aluminium coating | 200 to 300 nm10 |
| Coating thickness, Alodine 1200s on aluminium, average | 200 to 1000 nm11 |
| Temperature behavior | |
| Treating bath temperature, control table range | 20 to 35 °C2 |
| Treating bath temperature, operation range | 20 to 30 °C3 |
| Storage temperature of the powder | -10 to 40 °C7 |
| Maximum metal surface temperature when drying in an oven | < 60 °C8 |
| Upper temperature limit for unpainted hexavalent chromate parts | < 60 °C13 |
| Lower temperature limit for unpainted parts, time-limited | > 0 °C16 |
| Other measurements | |
| Operating pH of the Henkel treating solution | 1.3 to 1.8 -1 |
| Immersion or spray time in the treating solution | 15 to 180 s4 |
| Bath concentration as titration value (mL of titrant) | 5 to 19 mL5 |
| Hexavalent chromium per unit of bath titrant | 1.73 mg/mL9 |
| Share of chromium atoms that are hexavalent in a commercial coating | 23 %12 |
| Guidance exposure time at 60 °C for unpainted parts | 1 min14 |
| Guidance exposure time at 21 °C for unpainted parts | 168 h15 |
| Maximum time from conversion treatment to primer or adhesive | < 48 h17 |
Why choose it, and why not
Good for
- Corrosion protection with a paint base, in a film of 0.25 to 1 µm according to one finisher.
- Low electrical contact resistance in its Class 3 form, as PRC-5005 describes, with no numeric value in the sources read.
- Self-repair of small defects, because Cr(VI) migrates to defects, as Wikipedia and Grilli describe.
Watch out for
- Hexavalent chromium: NIOSH treats all Cr(VI) compounds as potential occupational carcinogens.
- Unpainted parts lose corrosion resistance above 60 °C (140 °F), and the loss increases with temperature and time.
- NASA-STD-6012A says MIL-DTL-5541 coatings alone would generally fail its environment Class 1 and Class 2 requirements on aluminium alloys. Those are the standard's environment classes, not the coating classes.
- The Henkel sheet gives two bath temperature ranges, 20 to 35 °C and 20 to 30 °C, and does not say which applies.
Chromate conversion coating is a long-standing aluminium pre-treatment that gives corrosion protection, a paint base and low electrical resistance in its Class 3 form. Its hexavalent chemistry brings a carcinogen concern, a 60 °C limit for unpainted parts, and no numeric electrical value in the sources read here.
Used in space products
Space hardware whose maker names Alodine 1200S (MIL-DTL-5541), with the part it is used for.
| Product | Where it is used |
|---|---|
| OreSatPSAS / Oregon State | Electrical-ground contact patches on frames |
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 | Alodine 1200S, BONDERITE M-CR 1200S AERO |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Operating pH of the Henkel treating solution | Range printed in the manufacturer data sheet; the control table repeats 1.3 to 1.8 | product BONDERITE M-CR 1200S AERO (Alodine 1200S) treating solutionbasis optimum bath pH stated by the manufacturer | — |
| 2 | Treating bath temperature, control table range | Range printed in the Operation and Control table of the manufacturer data sheet | product BONDERITE M-CR 1200S AERO treating solutiontemperature in source 68 to 95 °F | The Operation section prints a narrower range for the same bath, 20 to 30 °C (70 to 100 °F). Both ranges are recorded because the sheet does not reconcile them. |
| 3 | Treating bath temperature, operation range | Range printed in the Operation section of the manufacturer data sheet | product BONDERITE M-CR 1200S AERO treating solutiontemperature in source 70 to 100 °F | Narrower than the control-table range (20 to 35 °C) for the same bath. |
| 4 | Immersion or spray time in the treating solution | Range printed in the Operation and Control table (Time, sec.) | product BONDERITE M-CR 1200S AERO treating solutionprocess immersion or spray | The Operation section gives the same range as 15 seconds to 3 minutes. |
| 5 | Bath concentration as titration value (mL of titrant) | Range printed in the Operation and Control table as the concentration range in mL of titrant; the control procedure says to stay within plus or minus 1 point of the value that gives the desired result | product BONDERITE M-CR 1200S AERO treating solutionbasis titration of a 5 mL sample, control procedure | — |
| 6 | Shelf life of unopened powder | Value printed in the storage table of the manufacturer data sheet | form powder as suppliedpackaging unopened original packaging | — |
| 7 | Storage temperature of the powder | Range printed in the storage table of the manufacturer data sheet | form powder as supplied | — |
| 8 | Maximum metal surface temperature when drying in an oven | Limit printed in the Drying section of the manufacturer data sheet, to maintain optimum corrosion resistance | basis metal surface temperature when an oven or other heat source is usedtemperature in source 150 °F | — |
| 9 | Hexavalent chromium per unit of bath titrant | Conversion factor printed in the Concentration part of the Control Procedure | basis 1 mL of titrant equals 1.73 mg/mL of hexavalent chrome in BONDERITE M-CR 1200S AERO | — |
| 10 | Coating thickness, typical dry aluminium coating | Range printed in the Chemistry section of the Wikipedia article | basis typical dry coating when process variables are adjusted to give it | Wikipedia gives a typical dry film of 200 to 300 nm; the finisher page gives 0.25 to 1 µm. Both are kept. |
| 11 | Coating thickness, Alodine 1200s on aluminium, average | Range printed in the Aluminium section of the Wikipedia article | product Alodine 1200ssubstrate aluminiumbasis average | — |
| 12 | Share of chromium atoms that are hexavalent in a commercial coating | Value stated in the Chemistry section of the Wikipedia article; the primary study was not opened | coating commercial aluminium chromate coatingregion except in a region close to the metal | — |
| 13 | Upper temperature limit for unpainted hexavalent chromate parts | Requirement stated in NASA-STD-6012A section 4.6.2 | coating unpainted hexavalent chromate conversion coated partstemperature in source 140 °F | — |
| 14 | Guidance exposure time at 60 °C for unpainted parts | Guidance row in the Appendix E table of NASA-STD-6012A; the appendix says no literature supports exposure time limits | temperature 60 °C (140 °F)coating unpainted hexavalent chromate conversion coating | — |
| 15 | Guidance exposure time at 21 °C for unpainted parts | Guidance row in the Appendix E table of NASA-STD-6012A | temperature 21 °C (70 °F)coating unpainted hexavalent chromate conversion coating | — |
| 16 | Lower temperature limit for unpainted parts, time-limited | Guidance in Appendix E of NASA-STD-6012A, which says water in the coating may freeze or sublime as the structure cracks | coating unpainted hexavalent chromate conversion coated partsduration limit not longer than 1 minute below this temperature | — |
| 17 | Maximum time from conversion treatment to primer or adhesive | Process requirement stated in NASA PRC-5005 Rev. D, section 3.0 | requirement primer or adhesive must be applied in less than 48 hours after the conversion coating process for adequate adhesion | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Self-healing in service, after scratches or pits form in the film | low | Cr(VI) in the film migrates to defects and helps repassivate pits.1 |
| Unpainted parts above 60 °C (140 °F) during drying, fabrication or service | moderate | Unpainted chromate coatings lose corrosion resistance above 60 °C.2 |
| Ageing in air | moderate | Long ageing produces microcracks that a limited Cr(VI) supply is unlikely to repair.3 |
| Alloys with copper or intermetallic particles | moderate | The film is thinner over intermetallic particles, so it is less even on some alloys.4 |
| Below freezing, unpainted parts | moderate | Below 0 °C for more than 1 minute, the coating can crack and expose the metal.5 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Self-healing in service, after scratches or pits form in the film | The coating is a mix of Cr(III) and Cr(VI) oxides. When it contacts an electrolyte, the Cr(VI) migrates to defects in the layer, where it can repassivate corrosion pits. Grilli notes that it is unclear how ageing and the loss of water affect this self-healing. The mechanism is described from the literature in a thesis, not measured in the sources read here. | basis mechanism summarised in a PhD thesis chapter, no test conditions given |
| 2 | Unpainted parts above 60 °C (140 °F) during drying, fabrication or service | NASA quotes MIL-DTL-5541F: unpainted conversion coatings start to lose corrosion resistance at 60 °C (140 °F) or higher. The coating dehydrates and its chromates become insoluble. Protection falls as temperature and exposure time rise, and dew point also changes how long a coating tolerates heat. | temperatures 60 °C (140 °F) and aboveexposure time Appendix E table: 1 minute at 60 °C down to 168 hours at 21 °C |
| 3 | Ageing in air | Grilli reports that ageing in air causes the loss of water from the film and a developing network of microcracks. These cracks may be pathways to the aluminium, and a limited Cr(VI) reservoir is unlikely to repair them. The ageing rate and crack growth were not measured in the sources read. | basis literature summarised in a thesis chapter, no ageing time or humidity given |
| 4 | Alloys with copper or intermetallic particles | Juffs and co-workers, cited by Grilli, found the coating on the aluminium matrix about 10 times thicker than on an intermetallic phase. The coating is therefore uneven on alloys with second-phase particles, and copper-rich alloys can change its composition. | basis macroscopic intermetallic phases coupled to aluminium, as cited in the thesis |
| 5 | Below freezing, unpainted parts | NASA says water molecules in the coating may freeze or sublime as its structure cracks, possibly exposing the base metal. The guidance is that unpainted parts should not be exposed below 0 °C for longer than 1 minute. | temperature below 0 °C (32 °F)duration longer than 1 minute |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The coating is made in a hexavalent chromium bath, and hexavalent chromium compounds are a recognised occupational hazard. The sources do not give toxicity numbers for this product.
- The chemistry
- NIOSH considers all Cr(VI) compounds to be potential occupational carcinogens. The Henkel sheet's titration factor shows the bath contains hexavalent chrome: 1 mL of titrant equals 1.73 mg/mL of hexavalent chrome.
- Wet parts and residues
- About 23% of the chromium atoms in a commercial aluminium coating are hexavalent, except near the metal. These residues can migrate when the coating is wetted.
- Alternatives
- Wikipedia says trivalent chromium alternatives are considerably less toxic. RoHS and REACH encourage the elimination of hexavalent chromium, including in chromate processes.
If the coating overheats or freezes
These are limits in NASA-STD-6012A for unpainted parts, not failure test results.
- Heat
- Unpainted parts should not be exposed above 60 °C (140 °F). At 60 °C the guidance allows about 1 minute, and at 21 °C about 168 hours.
- Cold
- Unpainted parts should not be exposed below 0 °C for more than 1 minute, because the water in the coating may freeze and crack the film.
- Drying
- The Henkel sheet limits the metal surface temperature in a drying oven to 60 °C (150 °F), to maintain corrosion resistance.
Handling and storage
- Powder
- The powder is brown and should be stored unopened between -10 and 40 °C. Its shelf life in unopened packaging is 48 months.
- Bath
- Mild steel containers slowly decompose the working solution. The sheet recommends 300 series stainless steel tanks, with 316L preferred.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Loss of corrosion protection on unpainted parts above 60 °Cmoderate severity | Drying, fabrication or service above 60 °C (140 °F)The coating dehydrates and its chromates become insoluble, so corrosion resistance falls. The effect grows with temperature and exposure time. |
| Cracking of the film in the coldmoderate severity | Unpainted parts below 0 °C (32 °F) for more than 1 minuteWater in the coating may freeze or sublime as the structure cracks, possibly exposing the base metal. |
| Microcracks from long ageingmoderate severity | Ageing of the coating in air, which removes water from the filmA network of microcracks develops that a limited Cr(VI) reservoir is unlikely to repair, so the self-healing action may weaken. |
| Poor paint or bond adhesion after delaymoderate severity | Primer or adhesive applied 48 hours or more after the conversion treatmentNASA PRC-5005 says adequate adhesion needs application in less than 48 hours. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Workers handling wet parts, and waste from the process | About 23% of chromium atoms in a commercial aluminium coating are hexavalent, except near the metal, and these residues can migrate when the coating is wetted. |
Handling and storage
- The Henkel sheet says dried, unfinished parts should not be handled bare-handed; use plastic or clean cotton gloves.
- Storing the working solution in mild steel containers slowly decomposes it. Process tanks should be 300 series stainless steel, with 316L preferred.
- Rinse the coating after application so the acids and salts in the process solution are removed before the coating dries.
Mitigations
- Type II coatings have no hexavalent chromium, but PRC-5005 says Type I outperforms Type II in corrosion tests, especially in filiform and deep scratch tests, and recommends Type I for most flight hardware.
- Wikipedia says trivalent chromium alternatives have been developed because they are considerably less toxic than hexavalent chromium.
Supply and geography
How common the raw materials are and where they come from.
Chromium (mine production, the source of chromium chemicals)
- Top producers (2025)
- South Africa 45.1%, Turkey 17.6%, Kazakhstan 13.7%, India 5.9%
- Recycling
- USGS: recycled chromium in stainless-steel scrap accounted for 21% of US apparent consumption in 2025.
- Substitutes
- USGS: chromium has no substitute in stainless steel or in superalloys. The chapter does not discuss chromate conversion coatings.
Chromium-containing chemicals (US import sources)
- Top producers
- Kazakhstan 25%, China 19%, Germany 14%, India 13%
- Recycling
- Not stated in the chromium chapter for chemicals.
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: chromate-conversion-coating
spore_version: 0.2
family: coatings
name: Chromate conversion coating
abbreviation: Alodine 1200S (MIL-DTL-5541)
role: thin chemical conversion film on aluminium for corrosion protection, paint adhesion and low electrical contact resistance
category: coatings
type: conductive-coatings
summary: |
Chromate conversion coating is a thin film that a chromate bath grows on aluminium alloys. One finisher gives its thickness as 0.25 to 1 µm, and Wikipedia gives 200 to 300 nm as typical for a dry coating. It protects against corrosion, gives paint a base and keeps electrical contact resistance low, which is why NASA process specification PRC-5005 names a Class 3 coating for lower electrical resistance.
best_for: Corrosion protection and a paint base on aluminium structures, and low-resistance electrical contact in its Class 3 form
weakest_at: 'Hexavalent chemistry: NIOSH treats Cr(VI) compounds as potential occupational carcinogens, and unpainted parts must not go above 60 °C'
identity:
formula: Mainly hydrated chromium(III) oxide with some chromium(VI) bound in it, grown on the aluminium surface as an amorphous film
designations:
- system: Trade name
code: Alodine 1200S
source: conro
where: Cover page, text 'Known as Alodine 1200S'
- system: Trade name
code: BONDERITE M-CR 1200S AERO
source: conro
where: Title and product description
source: wiki
where: 'Chemistry section: the dry aluminium coating is mostly chromium(III) oxide, with very little Al2O3'
tags:
environments: []
stresses:
- extreme-cold
applications:
- structures
- electronics-and-chips
properties:
- benchmark: bath_ph
label: Operating pH of the Henkel treating solution
value: 1.3
value_high: 1.8
bound: range
unit: '-'
scope: material
conditions:
product: BONDERITE M-CR 1200S AERO (Alodine 1200S) treating solution
basis: optimum bath pH stated by the manufacturer
method: Range printed in the manufacturer data sheet; the control table repeats 1.3 to 1.8
status: ground
source: conro
where: Control Procedure, pH Determination; Operation and Control table, row pH
- benchmark: bath_temperature
label: Treating bath temperature, control table range
value: 20
value_high: 35
bound: range
unit: °C
scope: material
conditions:
product: BONDERITE M-CR 1200S AERO treating solution
temperature_in_source: 68 to 95 °F
method: Range printed in the Operation and Control table of the manufacturer data sheet
status: ground
note: The Operation section prints a narrower range for the same bath, 20 to 30 °C (70 to 100 °F). Both ranges are recorded because the sheet does not reconcile them.
source: conro
where: Operation and Control table, row Temperature, °C
- benchmark: bath_temperature
label: Treating bath temperature, operation range
value: 20
value_high: 30
bound: range
unit: °C
scope: material
conditions:
product: BONDERITE M-CR 1200S AERO treating solution
temperature_in_source: 70 to 100 °F
method: Range printed in the Operation section of the manufacturer data sheet
status: ground
note: Narrower than the control-table range (20 to 35 °C) for the same bath.
source: conro
where: Operation section, Operation, Temperature
- benchmark: treatment_time
label: Immersion or spray time in the treating solution
value: 15
value_high: 180
bound: range
unit: s
scope: material
conditions:
product: BONDERITE M-CR 1200S AERO treating solution
process: immersion or spray
method: Range printed in the Operation and Control table (Time, sec.)
status: ground
note: The Operation section gives the same range as 15 seconds to 3 minutes.
source: conro
where: Operation and Control table, row Time, sec.; Operation section, Time
- benchmark: bath_titration_points
label: Bath concentration as titration value (mL of titrant)
value: 5
value_high: 19
bound: range
unit: mL
scope: material
conditions:
product: BONDERITE M-CR 1200S AERO treating solution
basis: titration of a 5 mL sample, control procedure
method: Range printed in the Operation and Control table as the concentration range in mL of titrant; the control procedure says to stay within plus or minus 1 point of the value that gives the desired result
status: ground
source: conro
where: Operation and Control table, row Concentration range, mL; Control Procedure, Concentration
- benchmark: shelf_life
label: Shelf life of unopened powder
value: 48
unit: months
scope: material
conditions:
form: powder as supplied
packaging: unopened original packaging
method: Value printed in the storage table of the manufacturer data sheet
status: ground
source: conro
where: Storage table, row Shelf-life
- benchmark: storage_temperature
label: Storage temperature of the powder
value: -10
value_high: 40
bound: range
unit: °C
scope: material
conditions:
form: powder as supplied
method: Range printed in the storage table of the manufacturer data sheet
status: ground
source: conro
where: Storage table, row Temperature, °C
- benchmark: max_drying_temperature
label: Maximum metal surface temperature when drying in an oven
value: 60
bound: upper
unit: °C
scope: material
conditions:
basis: metal surface temperature when an oven or other heat source is used
temperature_in_source: 150 °F
method: Limit printed in the Drying section of the manufacturer data sheet, to maintain optimum corrosion resistance
status: ground
source: conro
where: Drying section
- benchmark: hexavalent_chromium_per_titrant
label: Hexavalent chromium per unit of bath titrant
value: 1.73
unit: mg/mL
scope: material
conditions:
basis: 1 mL of titrant equals 1.73 mg/mL of hexavalent chrome in BONDERITE M-CR 1200S AERO
method: Conversion factor printed in the Concentration part of the Control Procedure
status: ground
source: conro
where: Control Procedure, Concentration
- benchmark: coating_thickness
label: Coating thickness, typical dry aluminium coating
value: 200
value_high: 300
bound: range
unit: nm
scope: material
conditions:
basis: typical dry coating when process variables are adjusted to give it
method: Range printed in the Chemistry section of the Wikipedia article
status: ground
note: Wikipedia gives a typical dry film of 200 to 300 nm; the finisher page gives 0.25 to 1 µm. Both are kept.
source: wiki
where: Chemistry section, Typical thickness
- benchmark: coating_thickness
label: Coating thickness, Alodine 1200s on aluminium, average
value: 200
value_high: 1000
bound: range
unit: nm
scope: material
conditions:
product: Alodine 1200s
substrate: aluminium
basis: average
method: Range printed in the Aluminium section of the Wikipedia article
status: ground
source: wiki
where: Aluminium section, Thickness
- benchmark: hexavalent_chromium_fraction
label: Share of chromium atoms that are hexavalent in a commercial coating
value: 23
unit: '%'
scope: material
conditions:
coating: commercial aluminium chromate coating
region: except in a region close to the metal
method: Value stated in the Chemistry section of the Wikipedia article; the primary study was not opened
status: ground
source: wiki
where: Chemistry section, Hexavalent chromium residues
- benchmark: unpainted_coating_max_temperature
label: Upper temperature limit for unpainted hexavalent chromate parts
value: 60
bound: upper
unit: °C
scope: material
conditions:
coating: unpainted hexavalent chromate conversion coated parts
temperature_in_source: 140 °F
method: Requirement stated in NASA-STD-6012A section 4.6.2
status: ground
source: std6012
where: Section 4.6.2, requirement CPR 24
- benchmark: unpainted_exposure_time
label: Guidance exposure time at 60 °C for unpainted parts
value: 1
unit: min
scope: material
conditions:
temperature: 60 °C (140 °F)
coating: unpainted hexavalent chromate conversion coating
method: Guidance row in the Appendix E table of NASA-STD-6012A; the appendix says no literature supports exposure time limits
status: ground
source: std6012
where: Appendix E, guidance table, first row
- benchmark: unpainted_exposure_time
label: Guidance exposure time at 21 °C for unpainted parts
value: 168
unit: h
scope: material
conditions:
temperature: 21 °C (70 °F)
coating: unpainted hexavalent chromate conversion coating
method: Guidance row in the Appendix E table of NASA-STD-6012A
status: ground
source: std6012
where: Appendix E, guidance table, last row
- benchmark: unpainted_cold_exposure_limit
label: Lower temperature limit for unpainted parts, time-limited
value: 0
bound: lower
unit: °C
scope: material
conditions:
coating: unpainted hexavalent chromate conversion coated parts
duration_limit: not longer than 1 minute below this temperature
method: Guidance in Appendix E of NASA-STD-6012A, which says water in the coating may freeze or sublime as the structure cracks
status: ground
source: std6012
where: Appendix E, paragraph after the guidance table
- benchmark: coating_to_primer_time
label: Maximum time from conversion treatment to primer or adhesive
value: 48
bound: upper
unit: h
scope: material
conditions:
requirement: primer or adhesive must be applied in less than 48 hours after the conversion coating process for adequate adhesion
method: Process requirement stated in NASA PRC-5005 Rev. D, section 3.0
status: ground
source: prc
where: Section 3.0, paragraph on adhesion
corrosion:
- environment: Self-healing in service, after scratches or pits form in the film
headline: Cr(VI) in the film migrates to defects and helps repassivate pits.
effect: The coating is a mix of Cr(III) and Cr(VI) oxides. When it contacts an electrolyte, the Cr(VI) migrates to defects in the layer, where it can repassivate corrosion pits. Grilli notes that it is unclear how ageing and the loss of water affect this self-healing. The mechanism is described from the literature in a thesis, not measured in the sources read here.
rating: low
conditions:
basis: mechanism summarised in a PhD thesis chapter, no test conditions given
source: grilli2010
where: Section 2.3, Chromate Conversion Coatings
- environment: Unpainted parts above 60 °C (140 °F) during drying, fabrication or service
headline: Unpainted chromate coatings lose corrosion resistance above 60 °C.
effect: 'NASA quotes MIL-DTL-5541F: unpainted conversion coatings start to lose corrosion resistance at 60 °C (140 °F) or higher. The coating dehydrates and its chromates become insoluble. Protection falls as temperature and exposure time rise, and dew point also changes how long a coating tolerates heat.'
rating: moderate
conditions:
temperatures: 60 °C (140 °F) and above
exposure_time: 'Appendix E table: 1 minute at 60 °C down to 168 hours at 21 °C'
source: std6012
where: Section 4.6.2 and Appendix E
- environment: Ageing in air
headline: Long ageing produces microcracks that a limited Cr(VI) supply is unlikely to repair.
effect: Grilli reports that ageing in air causes the loss of water from the film and a developing network of microcracks. These cracks may be pathways to the aluminium, and a limited Cr(VI) reservoir is unlikely to repair them. The ageing rate and crack growth were not measured in the sources read.
rating: moderate
conditions:
basis: literature summarised in a thesis chapter, no ageing time or humidity given
source: grilli2010
where: Section 2.3, Chromate Conversion Coatings
- environment: Alloys with copper or intermetallic particles
headline: The film is thinner over intermetallic particles, so it is less even on some alloys.
effect: Juffs and co-workers, cited by Grilli, found the coating on the aluminium matrix about 10 times thicker than on an intermetallic phase. The coating is therefore uneven on alloys with second-phase particles, and copper-rich alloys can change its composition.
rating: moderate
conditions:
basis: macroscopic intermetallic phases coupled to aluminium, as cited in the thesis
source: grilli2010
where: Section 2.3, paragraph citing Juffs et al.
- environment: Below freezing, unpainted parts
headline: Below 0 °C for more than 1 minute, the coating can crack and expose the metal.
effect: NASA says water molecules in the coating may freeze or sublime as its structure cracks, possibly exposing the base metal. The guidance is that unpainted parts should not be exposed below 0 °C for longer than 1 minute.
rating: moderate
conditions:
temperature: below 0 °C (32 °F)
duration: longer than 1 minute
source: std6012
where: Appendix E, paragraph after the guidance table
risks:
hazards:
- text: NIOSH considers all Cr(VI) compounds to be potential occupational carcinogens.
ghs: []
source: niosh-cr6
where: What this means to you section, Engineering Controls Database
- text: Wikipedia says hexavalent chromium compounds have been the topic of intense workplace and public health concern over carcinogenicity, and that they are highly regulated.
ghs: []
source: wiki
where: Safety section
- text: The Henkel data sheet says the powder's hazards are in its material safety data sheet and does not name the hexavalent compound. The safety data sheet was not opened, so no GHS codes are recorded for this product.
ghs: []
source: conro
where: Classification section
failure_risks:
- mode: Loss of corrosion protection on unpainted parts above 60 °C
trigger: Drying, fabrication or service above 60 °C (140 °F)
consequence: The coating dehydrates and its chromates become insoluble, so corrosion resistance falls. The effect grows with temperature and exposure time.
severity: moderate
source: std6012
where: Section 4.6.2; Appendix E
- mode: Cracking of the film in the cold
trigger: Unpainted parts below 0 °C (32 °F) for more than 1 minute
consequence: Water in the coating may freeze or sublime as the structure cracks, possibly exposing the base metal.
severity: moderate
source: std6012
where: Appendix E, paragraph after the guidance table
- mode: Microcracks from long ageing
trigger: Ageing of the coating in air, which removes water from the film
consequence: A network of microcracks develops that a limited Cr(VI) reservoir is unlikely to repair, so the self-healing action may weaken.
severity: moderate
source: grilli2010
where: Section 2.3, Chromate Conversion Coatings
- mode: Poor paint or bond adhesion after delay
trigger: Primer or adhesive applied 48 hours or more after the conversion treatment
consequence: NASA PRC-5005 says adequate adhesion needs application in less than 48 hours.
severity: moderate
source: prc
where: Section 3.0, paragraph on adhesion
side_effects:
- text: About 23% of chromium atoms in a commercial aluminium coating are hexavalent, except near the metal, and these residues can migrate when the coating is wetted.
affects: Workers handling wet parts, and waste from the process
source: wiki
where: Chemistry section, Hexavalent chromium residues; Safety section
handling:
- text: The Henkel sheet says dried, unfinished parts should not be handled bare-handed; use plastic or clean cotton gloves.
source: conro
where: Drying section
- text: Storing the working solution in mild steel containers slowly decomposes it. Process tanks should be 300 series stainless steel, with 316L preferred.
source: conro
where: Equipment section
- text: Rinse the coating after application so the acids and salts in the process solution are removed before the coating dries.
source: prc
where: Section 6.0
mitigations:
- text: Type II coatings have no hexavalent chromium, but PRC-5005 says Type I outperforms Type II in corrosion tests, especially in filiform and deep scratch tests, and recommends Type I for most flight hardware.
source: prc
where: Section 3.0, Usage
- text: Wikipedia says trivalent chromium alternatives have been developed because they are considerably less toxic than hexavalent chromium.
source: wiki
where: Safety section
uses:
- application: structures
device: Aluminium parts that are painted or left bare (Class 1A coating)
example: Henkel lists BONDERITE M-CR 1200S AERO on Qualified Product List QPL-81706 for Class 1A and Class 3 coatings, bare or painted, to MIL-DTL-5541.
source: conro
where: Application Areas
- application: electronics-and-chips
device: Aluminium parts where lower electrical contact resistance is required (Class 3 coating)
example: PRC-5005 defines Class 3 as protection against corrosion where lower electrical resistance is required.
source: prc
where: Section 2.0, classes
- application: structures
device: Aluminium surfaces to be painted or bonded
example: PRC-5005 says the coating is a good base for paint primers and only a fair base for bonding, and that the standard bonding method removes it during surface preparation.
source: prc
where: Section 3.0
supply:
- subject: Chromium (mine production, the source of chromium chemicals)
producers:
- country: South Africa
share_percent: 45.1
year: 2025
- country: Turkey
share_percent: 17.6
year: 2025
- country: Kazakhstan
share_percent: 13.7
year: 2025
- country: India
share_percent: 5.9
year: 2025
critical_lists: []
recycling: 'USGS: recycled chromium in stainless-steel scrap accounted for 21% of US apparent consumption in 2025.'
substitutes:
- 'USGS: chromium has no substitute in stainless steel or in superalloys. The chapter does not discuss chromate conversion coatings.'
source: usgs-mcs2026-chromium
where: World Mine Production and Reserves table, 2025e (world total 51,000 thousand t as printed; shares calculated by Space Mushroom from South Africa 23,000, Turkey 9,000, Kazakhstan 7,000 and India 3,000 thousand t); Recycling; Substitutes
- subject: Chromium-containing chemicals (US import sources)
producers:
- country: Kazakhstan
share_percent: 25
- country: China
share_percent: 19
- country: Germany
share_percent: 14
- country: India
share_percent: 13
critical_lists: []
recycling: Not stated in the chromium chapter for chemicals.
substitutes: []
source: usgs-mcs2026-chromium
where: Domestic Production and Use, Import Sources (2021 to 2024) paragraph; the share for the chemicals is the US import share, not the world share
media: []
documents:
- title: BONDERITE M-CR 1200S AERO (Alodine 1200S) Technical Data Sheet, Henkel, November 2019
type: datasheet
url: https://conro.com/downloads/Manuals/BONDERITE-M-CR-1200S-AERO-TDS.pdf
year: 2019
- title: NASA/JSC PRC-5005 Rev. D, Process Specification for the Chemical Conversion Coating of Aluminum Alloys (July 2020)
type: standard
url: https://nasa.gov/wp-content/uploads/2023/03/prc-5005-current.pdf
year: 2020
- title: NASA-STD-6012A, Corrosion Protection for Space Flight Hardware (approved 2022-03-23)
type: standard
url: https://standards.nasa.gov/sites/default/files/standards/NASA/A/2022-01-11-NASA-STD-6012A-Approved.pdf
year: 2022
- title: 'Grilli, Conversion coatings for aluminium alloys: a surface investigation for corrosion mechanisms (PhD thesis, University of Surrey, 2010)'
type: paper
url: http://esmat.esa.int/Publications/Published_papers/Conversion_coatings_for_aluminium_alloys.pdf
year: 2010
- title: 'USGS Mineral Commodity Summaries 2026: Chromium'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
year: 2026
- title: 'NIOSH Engineering Controls Database: Control of Hexavalent Chromium Exposures'
type: database
url: https://www.cdc.gov/niosh/engcontrols/ecd/detail7.html
- title: 'Wikipedia: Chromate conversion coating'
type: database
url: https://en.wikipedia.org/wiki/Chromate_conversion_coating
- title: 'Fictiv: Alodine chromate conversion coating finish page'
type: datasheet
url: https://fictiv.com/finishes/alodine-chromate-conversion-coating
gaps:
- No electrical contact resistance or surface resistance value for the Class 3 coating was found in any source opened. PRC-5005 names Class 3 for lower electrical resistance but gives no number. A forum thread on finishing.com quotes 5,000 microohms per square inch, but that is a second-hand forum quote and is not recorded as a property.
- MIL-DTL-5541 itself was not opened. Its Class 1A and Class 3 test requirements, salt spray hours and filiform test results are therefore not recorded.
- No salt spray, humidity or filiform corrosion test hours for this coating were found in the sources read.
- No flight, vacuum, outgassing or atomic-oxygen result for the coating was found. NASA-STD-6012A gives only temperature and exposure limits, and the outgassing and erosion data are not in any source opened.
- Coating mass (coating weight) per area was not found as a number. The Fictiv page and forum thread give it only in general terms.
- Bath temperature conflicts in the Henkel sheet (20 to 35 °C in the control table, 20 to 30 °C in the operation section). Both are recorded; the sheet does not reconcile them.
- 'Thickness conflicts across sources: 0.25 to 1 µm (Fictiv) against 200 to 300 nm typical (Wikipedia). Both are recorded; the thickness for a given drawing should come from the drawing or the work instruction.'
- The hazard data rest on the NIOSH engineering controls page and the Wikipedia safety section. The Henkel powder's safety data sheet was not opened, and the hexavalent compound in the powder is not named in the sheet, so no GHS codes are recorded.
- The 23% hexavalent figure comes from a Wikipedia summary; the primary study was not opened.
- Atomic weights were not read in this run, so the recipe parts carry atom counts only.
- The chromium chapter in USGS MCS 2026 was read for supply, but the USGS 2025 critical minerals list was not opened, so no critical-list status is recorded for chromium.
- The aluminium substrate is not profiled here. Its supply and corrosion behaviour belong to the aluminium profiles.
- 'No environment tags: none of the sources opened ties this coating to a specific space environment such as low Earth orbit or the lunar surface.'
- The Henkel bath make-up figures (6.3 pounds per 100 gallons, and the metric equivalent printed as 7,5 kg per 1000 liters) were not recorded because the printed metric figure is ambiguous.
- No media images were selected for this profile.
sources:
conro:
title: Technical Data Sheet, BONDERITE M-CR 1200S AERO (Known as Alodine 1200S), Henkel
id: Henkel technical data sheet, reference 1.0, November 2019; MIL-DTL-5541 Class 1A and Class 3, QPL-81706
url: https://conro.com/downloads/Manuals/BONDERITE-M-CR-1200S-AERO-TDS.pdf
year: 2019
kind: datasheet
license: Manufacturer data sheet (cited, not reproduced)
prc:
title: NASA/JSC PRC-5005 Rev. D, Process Specification for the Chemical Conversion Coating of Aluminum Alloys
id: PRC-5005 Rev. D, July 2020
url: https://nasa.gov/wp-content/uploads/2023/03/prc-5005-current.pdf
year: 2020
kind: standard
license: NASA process specification (public)
std6012:
title: NASA-STD-6012A, Corrosion Protection for Space Flight Hardware
id: NASA-STD-6012A, approved 2022-03-23
url: https://standards.nasa.gov/sites/default/files/standards/NASA/A/2022-01-11-NASA-STD-6012A-Approved.pdf
year: 2022
kind: standard
license: NASA technical standard, approved for public release
grilli2010:
title: 'Conversion coatings for aluminium alloys: a surface investigation for corrosion mechanisms (PhD thesis, University of Surrey)'
id: Rossana Grilli, March 2010, hosted by ESA ESMAT
url: http://esmat.esa.int/Publications/Published_papers/Conversion_coatings_for_aluminium_alloys.pdf
year: 2010
kind: paper
license: Thesis (cited, not reproduced)
usgs-mcs2026-chromium:
title: Mineral Commodity Summaries 2026, Chromium
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
year: 2026
kind: report
license: public domain (USGS)
niosh-cr6:
title: 'NIOSH Engineering Controls Database: Control of Hexavalent Chromium Exposures'
url: https://www.cdc.gov/niosh/engcontrols/ecd/detail7.html
kind: web
license: public domain (CDC NIOSH)
wiki:
title: 'Wikipedia: Chromate conversion coating'
url: https://en.wikipedia.org/wiki/Chromate_conversion_coating
kind: web
license: CC BY-SA 4.0 (cited, not reproduced)
fictiv:
title: 'Fictiv finishes: Alodine chromate conversion coating'
url: https://fictiv.com/finishes/alodine-chromate-conversion-coating
kind: web
license: Supplier web page (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 17
unreachable: 2
caveats: 4
note: 'Written by an AI assistant on 2026-11-01 from the pages and PDFs named in each entry (Henkel data sheet and NASA PRC-5005 and NASA-STD-6012A extracted from PDF text). Not used: the PubChem chromium trioxide record (returned a browser verification page) and the NIOSH Pocket Guide entry for chromium (VI) (the link opened a different chemical). Caveats: the Henkel sheet gives two bath temperature ranges; the finisher and Wikipedia thickness ranges differ; the 23% figure is from a Wikipedia summary; the forum quote for contact resistance is not recorded as a value.'
story:
recipe:
line: 'Chromate conversion coating is a thin film formed on aluminium by reaction with an acidic chromate bath. The dry film is mostly chromium(III) oxide with very little aluminium oxide, and it holds some chromium(VI) within it (Wikipedia). Process: clean, rinse, deoxidise if the surface is heavily oxidised, rinse, treat, rinse, then dry (Henkel). The Henkel bath is acidic, at pH 1.3 to 1.8.'
parts:
- name: Chromium
symbol: Cr
role: The film-forming metal. Chromium(VI) in the bath is reduced to chromium(III), which forms the hydrated oxide; some chromium(VI) stays bound and can migrate to defects.
- name: Oxygen
symbol: O
role: Bound to chromium in the oxide film. Chromium(III) oxide is the main constituent of the dry coating.
- name: Aluminium
symbol: Al
role: The substrate. Aluminium is oxidised as the chromium is reduced, and very little aluminium oxide remains in the final film (Wikipedia; Grilli 2010).
risk_groups:
- title: For people
level: 1
verdict: Hexavalent chromium is the concern
lead: The coating is made in a hexavalent chromium bath, and hexavalent chromium compounds are a recognised occupational hazard. The sources do not give toxicity numbers for this product.
points:
- label: The chemistry
line: 'NIOSH considers all Cr(VI) compounds to be potential occupational carcinogens. The Henkel sheet''s titration factor shows the bath contains hexavalent chrome: 1 mL of titrant equals 1.73 mg/mL of hexavalent chrome.'
- label: Wet parts and residues
line: About 23% of the chromium atoms in a commercial aluminium coating are hexavalent, except near the metal. These residues can migrate when the coating is wetted.
- label: Alternatives
line: Wikipedia says trivalent chromium alternatives are considerably less toxic. RoHS and REACH encourage the elimination of hexavalent chromium, including in chromate processes.
- title: If the coating overheats or freezes
lead: These are limits in NASA-STD-6012A for unpainted parts, not failure test results.
points:
- label: Heat
line: Unpainted parts should not be exposed above 60 °C (140 °F). At 60 °C the guidance allows about 1 minute, and at 21 °C about 168 hours.
- label: Cold
line: Unpainted parts should not be exposed below 0 °C for more than 1 minute, because the water in the coating may freeze and crack the film.
- label: Drying
line: The Henkel sheet limits the metal surface temperature in a drying oven to 60 °C (150 °F), to maintain corrosion resistance.
- title: Handling and storage
points:
- label: Powder
line: The powder is brown and should be stored unopened between -10 and 40 °C. Its shelf life in unopened packaging is 48 months.
- label: Bath
line: Mild steel containers slowly decompose the working solution. The sheet recommends 300 series stainless steel tanks, with 316L preferred.
why: Chromate conversion coating is a long-standing aluminium pre-treatment. It puts a thin film on the metal that protects it from corrosion and gives paint a base. Grilli describes the film as low in surface electrical resistance, which the thesis calls an important feature for the space industry. NASA PRC-5005 uses Class 3 for coatings where lower electrical resistance is required, and Class 1A for maximum corrosion protection. Type I, the hexavalent version, is recommended for most flight hardware.
uses:
- where: Structures
line: Henkel lists its powder on Qualified Product List QPL-81706 for Class 1A and Class 3 coatings, bare or painted, to MIL-DTL-5541. NASA lets MIL-DTL-5541 coatings serve as a primer base or a temporary fabrication coating.
- where: Electrical grounding
line: PRC-5005 names Class 3 for protection where lower electrical resistance is required. The sources opened give no numeric resistance value for it.
- where: Paint and bonding preparation
line: The coating is a good base for paint primers and only a fair base for bonding. The standard bonding method removes it during surface preparation, and the primer or adhesive should go on within 48 hours.
can_do:
- label: Corrosion barrier
value: 0.25 to 1 µm
line: One finisher gives the film thickness as 0.25 to 1 µm. Wikipedia gives 200 to 300 nm as the typical dry coating, and 200 to 1000 nm as the average for Alodine 1200s on aluminium.
- label: Paint base
value: Within 48 hours
line: PRC-5005 says primer or adhesive must go on in less than 48 hours after the conversion treatment for adequate adhesion.
- label: Self-repair
value: Cr(VI) migrates
line: Chromium(VI) in the film migrates to defects, where it can repassivate pits. Grilli notes that ageing and water loss may limit this action.
- label: Process speed
value: 15 s to 3 min
line: The Henkel sheet gives 15 seconds to 3 minutes of treatment time, at a bath temperature of 20 to 30 °C in the operation section.
- label: Heat limit
value: 60 °C
line: Unpainted hexavalent chromate parts should not exceed 60 °C (140 °F), according to NASA-STD-6012A section 4.6.2.
compare: Anodize, covered by the anodized aluminium profile, grows an oxide skin that the profile describes as electrically insulating. Chromate conversion coating is a thin chemical film and is chosen where lower electrical resistance is needed, as NASA PRC-5005 describes for Class 3. Type II coatings avoid hexavalent chromium, but PRC-5005 says Type I consistently outperforms Type II in corrosion tests, and Grilli reviews chromium-free alternatives for aluminium without giving a single replacement value. The table below compares film thickness, the heat limit for unpainted parts and the bath pH.
compare_rows:
- label: Film thickness
benchmark: coating_thickness
- label: Upper temperature for unpainted parts
benchmark: unpainted_coating_max_temperature
- label: Bath pH
benchmark: bath_ph
handling:
- Specify the type and class on the drawing. PRC-5005 uses Type I unless the drawing says otherwise, and Class 3 where lower electrical resistance is needed.
- Keep unpainted parts at or below 60 °C (140 °F), and do not expose them below 0 °C for more than 1 minute.
- Apply primer or adhesive within 48 hours of the conversion treatment.
- Wear plastic or clean cotton gloves on dried, unfinished parts.
- Store the unopened powder between -10 and 40 °C. The shelf life is 48 months.
good_for:
- Corrosion protection with a paint base, in a film of 0.25 to 1 µm according to one finisher.
- Low electrical contact resistance in its Class 3 form, as PRC-5005 describes, with no numeric value in the sources read.
- Self-repair of small defects, because Cr(VI) migrates to defects, as Wikipedia and Grilli describe.
watch_out:
- 'Hexavalent chromium: NIOSH treats all Cr(VI) compounds as potential occupational carcinogens.'
- Unpainted parts lose corrosion resistance above 60 °C (140 °F), and the loss increases with temperature and time.
- NASA-STD-6012A says MIL-DTL-5541 coatings alone would generally fail its environment Class 1 and Class 2 requirements on aluminium alloys. Those are the standard's environment classes, not the coating classes.
- The Henkel sheet gives two bath temperature ranges, 20 to 35 °C and 20 to 30 °C, and does not say which applies.
verdict: Chromate conversion coating is a long-standing aluminium pre-treatment that gives corrosion protection, a paint base and low electrical resistance in its Class 3 form. Its hexavalent chemistry brings a carcinogen concern, a 60 °C limit for unpainted parts, and no numeric electrical value in the sources read here.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Technical Data Sheet, BONDERITE M-CR 1200S AERO (Known as Alodine 1200S), Henkel | datasheet | 2019 | 13 values | |
| NASA/JSC PRC-5005 Rev. D, Process Specification for the Chemical Conversion Coating of Aluminum Alloys | standard | 2020 | 6 values | |
| NASA-STD-6012A, Corrosion Protection for Space Flight Hardware | standard | 2022 | 8 values | |
| Conversion coatings for aluminium alloys: a surface investigation for corrosion mechanisms (PhD thesis, University of Surrey) | paper | 2010 | 4 values | |
| Mineral Commodity Summaries 2026, Chromium | report | 2026 | 2 values | |
| NIOSH Engineering Controls Database: Control of Hexavalent Chromium Exposures | web | 1 value | ||
| Wikipedia: Chromate conversion coating | web | 7 values | ||
| Fictiv finishes: Alodine chromate conversion coating | web | 0 values |
Updated