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topic 8906

Safety Aspects of Chromate Conversion Coating on Aluminum



A discussion started in 2001 and continuing through 2020 so far.
Adding your Q. / A. or Comment will restore it to our busy Current Topics page

2001

Q. Can you please advise what is the current knowledge on the Occupational Health and safety aspects of the chromate layer of the chromate conversion treatment of Aluminium?

S Chong
- Sydney. Australia


2007

Q. Can you please advise what is the current knowledge on the Occupational Health and safety aspects of the chromate layer of the chromate conversion treatment of Aluminium?

Ramesh Kumar.V.k
Engineer - Kerala, India


2007

A. Hi Ramesh. That question has remained unanswered for years despite being seen by thousands of readers :-)

I think the problem is that this is a good topics for research papers, but probably not for the short and quick answers appropriate to a public forum. But in brief, many governments consider hexavalent chromate to be carcinogenic; so a chromate conversion coated piece of aluminum therefore has a carcinogenic coating on it.

As a minimum then, operators should always wear gloves when handling. Viable trivalent chromate conversion coatings now exist that meet Mil-DTL-5541 [link is to free spec at Defense Logistics Agency, dla.mil]. Please explain your own situation. Thanks.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


2007

Q. Thanks so much Mr.Ted Mooney. I would like to explain the situation. Our organisation manufactures a large number of aluminium products for space launch vehicle applications. It includes chassis for electronic packages, components required for integrating various electronic packages/systems to the structure of the launch vehicle/ sub-assemblies.These products are either anodised/yellow chromated. Wherever electrical conductivity is to be maintained, yellow chromating using Alodine 1200 is being done. The chromate treated components are handled by employees without gloves during inspection, further integration operations and transportation. This practice is being practised for the last 20 or 30 years.Our government has not banned chromating. Whether the persons handling the chromated components are also at risk? Kindly advise.

Ramesh Kumar.V.K
- Trivandrum, Kerala, India


2007

Unfortunately, hazards are always relative, never yes/no, and there is no direct answer to your question, Ramesh. Chromate is not so hazardous that we can point to clear imminent injury, but it is considered a carcinogenic material and no one has proven its safety through extensive repeatable tests where some employees touch chromated parts every day for years and others never touch such parts for years :-)

Instead, think in terms of the new Mil-DTL-5541 [link is to free spec at Defense Logistics Agency, dla.mil] approved TCP chromates that contain no hexavalent chrome. If that is not appropriate, then yet again I urge you to consider gloves. Many of we consultants to the industry can't even count the installations that we are familiar with where people once insisted that wearing gloves would be impractical, but now do without considering it a burden. People should not be spending their workday handling parts which have a hexavalent chromium coating on them. G00d luck.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha



Aluminum Chromate Questions - powder coat prep

October 22, 2020 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Aluminum Chromate treated aluminum extrusions -- sanding and welding extrusions -

Is there risk of releasing HexChrome while sanding the treated aluminum extrusion (180 grit)? Tig welding the aluminum extrusion? Long term vision is a manufacturing environment -- day to day standard process and ensuring people are working in a safe environment.

Finished product to be powdercoated. Example would be an aluminum boat.

Joe Roberts
- Greenville, South Carolina


October 2020

A. Hi Joe. Although I cannot quantify the risk of sanding and welding hexavalent chromate conversion coated aluminum boats, the answer is that yes there is risk. Most of the world is switching to trivalent chromates and you probably should as well.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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