The Voice of the Finishing Industry since 1936

  • PF Youtube
  • PF Facebook
  • PF Twitter
  • PF LinkedIn
2/1/2013

Chemical Film Staining

Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

What technique is used to avoid staining on aluminum parts when chemical film per Mil-C-5541 is applied?

Share

Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

Q. What technique is used to avoid staining on aluminum parts when chemical film per Mil-C-5541 is applied? It seems that the bottom few drops dry on the very edge and leave a stain. J.C.

A. Here are some points to think about in this regard when doing the chem film process:

  • Although the bath concentration may vary a small amount depending on its condition, make sure it is not too concentrated. I recommend making up a new chem film bath at 1/2 oz/gal. An older, well-used bath may require 1 oz/gal to perform well.
  • Bath temperature of 70-75°F (21-24°C) is ideal.
  • Rinse thoroughly in a double-counter flow-rinse tank system, followed by a clean deionized (DI) water rinse, then a final warm rinse (150°F, 65°C maximum). That’s four rinses altogether.

The bottom line is, if the bath is too concentrated and/or the parts are not rinsed well enough, the staining is more likely to occur. 

Related Topics

RELATED CONTENT

  • Plating Process Control

    The cornerstone of quality and productivity for any finishing operation, process control is a plater’s key to success. To find out how far techniques have come, where they’re headed in the future, and how platers can raise the bar, Products Finishing convened a panel of experts for a roundtable discussion on the topic. With well over 100 years of combined plating experience, experts Greg Arneson, Art Kushner, Peter Gallerani and Joelie Zak share their thoughts.

  • Stripping Anodic Coating

    Question: What is the best way to strip an anodize coating?

  • Aluminum Surface Finishing Corrosion Causes and Troubleshooting

    In this paper, a review of several process solutions, examining coolants, solvent cleaning, alkaline clean/etch and deoxidizing/desmutting, listing intended and unintended chemical reactions along with possible mechanisms that would favor corrosion formation.


Resources