Why must aluminum panels have Alodine-1200S before Exterior dirt-up test of High-Gloss Paints

Hi I'm Jessa From Philippines and working in an R&D Laboratory of a Paint Company. Alodine 1200S is the required treating solution for the aluminum panels in one of the procedures for dirt pick-up resistance test of an exterior paint. panels should be treated first in Alodine 1200S before a test paint was drawn down on the panels. I just want to ask, what is the importance of treating the panels in an Alodine 1200S & I have no idea if it is a solution? What is the relevance of treating the panels with the application test? maybe you could help me with this so that I could request for this sample in the purchasing dept. The procedure did not state the duration of treating the panels, if it is immersion, for how long will I immerse the aluminum panels?

Thanks a lot,

Hi, Jessa. Alodine-1200S is a Henkel trade name for a chromate conversion process. The real aluminum parts would employ chromate conversion coating before painting, so I guess that's why your test panels are supposed to as well. However, the process is not a simple dip in the Alodine, it's a series of steps including cleaning, etching, desmutting, and Alodine dip. The technical data sheet for the Alodine will give you the recommended immersion time.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey