efs-2500 paint stripper removed anodize coating -safe?

[johnSchwaner]

An aircraft hose we made with blue anodized aluminum fittings had the anodizing removed to bare aluminum wherever efs-2500 paint stripper splashed onto it. This "envirnomently friendly" paint stripper is advertised as safe on aluminum and is being used on many aircraft.

If it's removes anodizing - isn't it removing aluminum and potentially corrosive? Whould we be concerned?

Examining the fitting under a microscope doesn't show any pitting and otherwise the fitting is in good condition - although it looks ugly!


-John

 

[MikeHalloran]

Chances are, the anodizing is still there, but the sealer (with the blue tint) that protects the aluminum under the anodize, is gone. Which means the fitting will corrode if not protected, e.g. by reapplication of anodizing sealer, or ... something.



Mike Halloran
Pembroke Pines, FL, USA

 

[kenvlach]

Checked the MSDS for EFS-2500:

http://www.rusteco.com/efs2500f2.pdf

"pH 5.6-6.7" -- no problem for anodize.

"Contains 1-7% hydrogen peroxide." -- Aha, the oxidizer attacked (bleached) the dye. Poorly sealed anodize. So, agree with Mike (except for his anodizing terminology -- dyeing & sealing are separate steps.)

EFS-2500 also contain benzyl alcohol, a solvent, but the color disappeared rather than ran. Plus, the 'Blue A' dye used by most anodizers is extremely easy to bleach -- a few seconds for hypochlorite when doing wastewater treatment.

 

[swall]

Check the surface of the fitting with a continuity meter at several points. Zero continuity means the anodic film is still there.

 

[johnSchwaner]

Thankyou for the excellent responses. I get a little nervous when paint stripper drips on our product, but now I won't worry about it.

I'm amazed that hydrogen peroxide and benzyl alcohol can strip paint so well. Why have we been using that nasty stuff for all of these years?

 

[MechanicalChef]

"Check the surface of the fitting with a continuity meter at several points. Zero continuity means the anodic film is still there."

I'd use an ohm meter myself. Depending on the coating thickness, I'm betting he'll still have 'some' continuity. When I did type-II anodizing years ago, the resistance of our coated-plates was significantly higher than bare Al, but we did have continuity. Though, we were doing backroom-anodizing as well, so I can't attest to the quality of said coating.....they were pretty though.