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Ted Mooney, P.E. RET
The authoritative public forum
for Metal Finishing 1989-2025
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Is Blue Alodine Bad?
QUICKSTART:
(to provide context, hopefully helping readers more quickly understand the Q&A's)
"Alodine" is a Henkel trade name for their chromate conversion coatings for aluminum.
"Iridite" is Macdermid's trade name for theirs.
The slang "chem-film" is often used in the USA.
MIL-DTL-5541 [⇦ this spec on DLA] is the most common specification for the process.
(to provide context, hopefully helping readers more quickly understand the Q&A's)
"Alodine" is a Henkel trade name for their chromate conversion coatings for aluminum.
"Iridite" is Macdermid's trade name for theirs.
The slang "chem-film" is often used in the USA.
MIL-DTL-5541 [⇦ this spec on DLA] is the most common specification for the process.
Aluminum How-To
"Chromating - Anodizing - Hardcoating"
by Robert Probert
Also available in Spanish
You'll love this book. Finishing.com has sold almost a thousand copies without a single return request :-)
I have been acid etching and treating Stearman Biplane parts with Alodine 1201 ⇦ this on eBay or Amazon [affil links] . Castings and panels have been coming out of the solution a bright to dark blue color. Is the solution bad or is the color due to copper content of the aluminum? (which is world war II vintage and unknown.) Is a blue conversion coating safe to prime?
Luis F. Villar MD- Stuart, Florida
2002
A. Taken fron Henkel Bulletin ...
"Variations in color result from different alloys, metal hardness,
metal age, method of cleaning, etc."
Painter - San Jose Costa Rica
November 17, 2021
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