Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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What is "Chem film"?
Q. What is chem film and why do metals need this? What would these metals be used for?
- Carlsbad, California
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A. To me 'Chem Film' means MIL-C-5541 chromate conversion coating of aluminum, but I may not be able to argue with someone who says it means something else to them.  Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey A. Search this site for chromate, phosphate, conversion coating, and you will find out which metals will take a 'chem film'. I assume this is for a research project or a book report. 
 Tom Pullizzi Falls Township, Pennsylvania |
Q. I HAVE SOME ALUMINUM PARTS THAT HAVE BEEN COATED WITH CHEM FILM AND NEED TO REMOVE THE COATING WITH A METHOD OTHER THAN GRIT BLASTING. ANY SUGGESTIONS FOR A CHEMICAL IMMERSION STRIP METHOD THAT WILL NOT ATTACK THE ALUMINUM SUBSTRATE ?
ROY B [surname deleted for privacy by Editor]- SAN ANTONIO, Texas
A. ROY B,
I have found a solution when undiluted can remove all chem film applied to a product in about 5-10 min, we have run a couple test runs with this product, and it works great, longer immersions such as 6 hours, 12 hours, and overnight, can slowly eat away at the product, but 5-10 min cleans it right off. The product will require a detailed rinse to remove all the solution from it. We used to buff our products when we had to remove the Chemfilm, we just happened to stumble across this product, and has saved countless hours in rework. Its a product called "Awesome Cleaner" bought from the dollar store, for 99 cents, we bout about 30 of them, filled a bucket, and haven't changed it since, going on 4 months now, and still as powerful chem film remover as when we first started.
- Coeur D' Alene, Idaho
A. Have you tried SEMCO PASA_JELL from PRC- DeSoto? It is a mixture of sulfuric and chromic acid that will not harm the aluminum but rather remove chem film and clean the surface.
John pepi- Wilmington, Massachusetts
September 24, 2008
A. You can strip the chem film with Nitric acid 30% and ammonium bifluoride 30-40 g/l or alkaline soak cleaner; time around 30 to 60 seconds
Alexi Bermudez- Tijuana, Baja California, Mexico
June 18, 2009
A. To strip the chem film we used deox when still fresh.
For aged chem film we use deox followed by etch and deox in the anodize line.
- Downey, California
June 29, 2012
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