Epoxy primer

[Jorge&Cindy]

I don't plan on painting my plane but want to apply epoxy primer to the wing spar tubes for corrosion protection. I'd hate to make the investment for the spray equipment and was wondering if it would be OK to brush the primer on? I'm using Poly fiber epoxy primer and the instructions only mention spraying.

[Mark]

Hi Jorge,
I brushed all my aluminum parts using the epoxy and it lays down ok - it's just not smooth and pretty - but gets a good coat on things. I also coated the inside of the spars by the "sloshing method" (see another thread about fabric covering).

[Skybolt]

Home Depot!

Get the foam brushes or the small little foam rollers and pans. This will be a little easier than a bristle brush to do the main areas.
You will probably need a small bristle brush to push the primer into the crevases.

If you are going through the extra work of coating your spars (probably 'cause you live near the coast in Florida) are you going to use a metal cleaner like Alumiprep 33?

Eric.

[Jorge&Cindy]

That would be my next question; what kind of prep do I need before primer?

[Skybolt]

Hi Jorge.

If I remember correctly, when I was building my Classic IV. What I read was do not scratch or avoid scratches in the aluminum tube, do not use a pencil on the aluminum tube for risk of creating a split. I believe I read this in the Skystar builders manual.
If this is the case, then do not attempt to use sandpaper.

You will have to clean it. Alumiprep 33 would be a good cleaner for this, you will have to rinse off with water and of course thorough dry before the application of epoxy primer.
If you don't want to do this then I suggest using MEK. Work on a small section at a time, very clean rags, wipe dry before the MEK can evaporate.

Eric.

[n85ae]

Use a brush, and just slop the stuff on. That's what I did, you'll never
(hopefully) see the spar anyway, so it doesn't need to be pretty.

You might think about using zinc chromate inside the spar since you
do have some dissimilar metal with the SS rivets and the zinc chromate
will provide a sacrificial element rather than nearby aluminum. I don't
think polyfiber epoxy primer will provide that.

Regards,
Jeff