DAKOTANOVASS

My Feedback: (17)

Yesterday I sprayed a plane with Brodak dope and I got pinholes over every surface except the open span areas of the wing. Here are the steps prior, I used Min-wax wood sealer over everything, then Stik-it to attached cover-all, then 3 coats of nitrate to seal all the coverall. I did not want the weave filled in so I did not use a primer before painting, first coat of dope was lite, second was a little heavier and before I applied the third I could see pinholes already, so the third coat was pretty heavy to try and bury them, but it didnt work. I suppose now I have to lightly sand and try to recoat. Anybody ever have a problem with the pinholes and what was your solution.

Terrell

sensei

No big deal, just sweep pin hole filler over all effected areas, allow to dry, sand until most the prime and pin hole filler is gone, and re-coat with primer, repeat all steps until your ready for top coat. This can take up to 3 applications in some cases, so just take your time.

Bob

Lone Star Charles

Sounds like you did what I would have done to seal the structure before attaching the covering. That always seemed to me to be the thing that prevents the pinholes. You didn't mention whether you sprayed or brushed the nitrate. I always brush on the nitrate. I feel as if brushing the nitrate allows the dope to form a film between the weave of the fabric; whereas spraying just blows the dope through the holes in the weaveand later on shows up as pinholes. If any of what I said makes sense. I still get pinholes from time to time and usually just lightly sand and recoat to fix.


Edit: Now that I think about it, on my last project, I used Brodak dope on the empennage assembly. I had a problem with pinholes. I'm not ready to blame the Brodak, but hmmmmmmmmmm.

DAKOTANOVASS

My Feedback: (17)

sensei

What kind of pin hole filler are you suggesting.

Lone star

I did brush the nitrate on.

sensei

You can just get a tube of the lacquer pin hole filler from any automotive paint supply store, that works just fine.

Bob

gene6029

I have never used min wax sealer myself to seal the wood first before useing dope as a finish. I just applied the stix it directly to the wood, ( UNLESS I WAS GOING TO USE A WATER BASED SYSTEM LIKE POLYCRYLIC ) In that case i sealed the wood with Deft sealer, then applied the stixit. Im thinking you had a reaction between the dope & sealer & stixit combo, since you say it was only over the areas where there was wood.To fill pin holes, Ace hardware sells small 12oz tubs of vinyl spackeling. I have used it in the past to fill pin holes. Just rub it over the area with your fingers and wipe it off with a rag. It fills them in nice. Let it dry completely before applying dope over it.....Gene

Sport_Pilot

Don't blame Brodak!  Pinholes are caused by moisture, usually in the air line.   Little droplets of water in the spray cause them.  Bleed off the water trapped in the bottom of the compressor.  Paint on a dry day, install a water trap in the air line if this is a constant problem.

carlgrover

Most automotive paint supply stores sell a small water trap that screws on to the end of your spray gun. This is the best place for a trap as it is the last chance to get the water out of the air line. They are pretty cheap and disposable.

Lone Star Charles

@Sport_Pilot - The original poster just described a problem with pinholes after using Brodak dope. I asked a few questions and found no fault in his application procedures. As a matter of fact, his techniques are very similar to mine. On the project that I mentioned I, too, got pinholes over the balsa surfaces on the empenagejust like the original poster. It just so happens that this was the only place on the project where I used Brodak dope. On the remainder of the airplane I used Stits products - no pinholes. Same day, same procedures, same temperatures, same humidity. Brodak areas on the empenage had pinholes, Stits areas on wing did not. I am not ready to blame Brodak, but two people with the similar application techniques and the only thing in common is pinholes in the Brodak. Hmmmmmmmmmmm!

PS: My air is dry. I only paint on low humidity days. I chill the air before it passes through a moisture separator. I drain the compressor before I start any work.

countilaw

Terrell,