Alodine or not

[jimgreen]

I'm having my machine painted by an autobody guy. He has never painted an aluminum aircraft...
The paint rep suggests scuff, alumiprep,followed by alodine before paint. I'm using Imron with a Dupont primer.
The aircraft has not flown yet and is being painted before assembly

Is it usual to alodine with this process?

 

[Randy Hooper]

Alodine helps with adhesion but also neutralizes the acid used in the etching process.
Yep, follow the paint manufacturers process and you want be sorry.

 

[az_gila]

DuPont does recommend it. They just call it 13206S Aluminum Conversion.

Full process sequence here -

http://pc.dupont.com/dpc/en/US/html...ion_Finishes_System_Recommendations_Props.pdf

 

[rbibb]

I would either Alodine (conversion coating) OR use a wash primer (Veriprime if using Dupont Products) but not both.

Alodine is best but hard to do correctly on large piece like a completed airplane. Easier to do on a small part (as it can be dipped in a tank, etc). Hardest part about alodine is keeping the surface wet for the time required for it to work. THen it really needs to be flushed off with water before it dries.

If you alodine use an epoxy primer after the alodine and not the wash primer. Do not use the an etching primer over Alodine. At least that is the firm advice I got from an industrial painter with a few decades of experience who painted all sorts of industrial parts to mil specs for a living.