-- The Home Page of the Finishing Industry
23+ years of serious education, promoting Aloha,
& the most fun you can have in metal finishing smiley
    no popups, no spam
on this site
current topics
topic 6702

Can we Chem Film (Chromate Conversion Coat) aluminum without deoxidizing


I seem to have a problem sometimes when we Chem Film parts with holes, that they have excess deoxidizer in the hole that causes a run-out on the chem film. My question is do I have to use a deoxidizer or can I just hot alkaline clean and hot water rinse and then chem film to stop this problem? I ran some sample's and the parts look acceptable without the deoxidizer step.

Kevin Duncan
- los angeles California


If the parts are scrupulously clean, and you get the same results (not merely acceptable) without it, I would document it in my quality program, and run them without the deox. It depends upon the purity of the aluminum; the more pure, the less you need the deox.

pooky tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania


We have found that the deoxidizer used has an effect on passing the salt requirements of Mil-C-5541 [link by ed. to spec at TechStreet]. The lack of a deoxidizer may compound the problem.


March 31, 2011

Hi, Kevin.

As an aid to understanding, please recognize that although this step is widely called "deoxidizing", it's not deoxidizing, it's desmutting -- it's the removal of copper, silicon, and/or other non-aluminum materials from the surface.

So, as Tom notes, the more pure the aluminum, the less necessary. And as William notes, the salt spray performance is likely to suffer if you're leaving that copper there. One more note, then, would be that if you etch, or over-clean, desmutting becomes more necessary. Good luck.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Comment to THIS thread START a NEW threadView CURRENT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices

©1995-2018, Inc., Pine Beach, NJ   -   About   -  Privacy Policy
How Google uses data when you visit this site.