Conversion Coating For Powder

Q. We use Alodine on 5053 aluminum and use a water based coating. We want to change to powder but we are also having to meet the RoHS requirement that does not allow hexavalent chrome in the Alodine. Have you found or know of an alternative to the Alodine that would give good adhesion and good Florida exposure. J.D.

 

A. Alodine is a registered trademark of Henkel Surface Technologies. It is known generically as a chromate conversion coating pretreatment used on aluminum products. Henkel and other chemical suppliers provide this conversion technology in non-chrome formulas. Additionally, there are several companies that offer “nano-technology” pretreatments that work on aluminum substrates that have proven to be as affective as chromate conversion coatings, but without the chrome. I recommend contacting these chemical suppliers and have them review your current method of application, process limitations, and corrosion requirements before selecting an alternative pretreatment. Remember always confirm your design by testing before you commit to the new technology.