Anyone use dope with an airbrush?

Hi all,

I tried this, and it all seems to gather up into small parts of the weave of the nylon and the stresses cause it to crack. It looks awful!

Does anyone sucessfully use an airbrush to apply dope (first coat or subsequent coats). Or is it a no hoper, and time to return to the trusty brush?

You have me confused here, because it works fine--just like any other sprayer, except doesn't cover as much or as fast.

What kind of dope are you using? What kind of thinner? How much? (Maybe you are not using enough thinner.) And what kind of spray gun? Are you getting moisture into the gun and could this be causing your problems?

Matt has painted small areas with an air brush. It is hard to paint a whole airplane because it is a slow process for larger areas (doesn't paint a lot at a time--but, then, that's what an airbrush is for). For s;maller planes, however, I see no reason why you couldn't paint the whole plane with it. Just remember to thin properly, and take your time. (It would be best to brush the first clear coats and filler on, and then sand to get a smooth base before starting with the air brush. Then for the color coats, it should be fine.)

Leonard Neumann

Hi Leonard,

I was a bit slow respoding to this, sorry.
The problem is it doesn't seem to work for me, so far I've only tried to spray dope. I thin it ("Grip" clear shrinking dope) about 50/50 with celulose thinners. I have tried it thicker, thinking it would build up better, but no

My airbrush is a very cheap one running off canned airbrush air. I've been spraying indoors near a radiator, but my really bad job was indoors but cold.

I don't think moisture is getting in anywhere, but I might just not be aware of it. Do you warm the mixutre before spraying or anything similar? I don't have any retarder, and wouldn't know where to get it.

When I spray it looks fine, nice and damp, after the airbrush passes. Then as it starts drying it goes milky. After several coats like this it ended up crystalising, and getting very bunched up in some places, without sealing the weave everywhere else.

Just wonderered if anyone had seen this and had some tips.

Thanks
Jonathan

We use a compressor with a moisture trap, so don't know about the canned process, but it should work. If it is getting milky in color, it sounds like moisture is forming, maybe even on the surface as it is drying. But if it is cracking, I am wondering if your thinner is compatible. A good quality lacquer thinner should work but there are degrees of speed in drying. too fast and you will get moisture problems and have trouble with adhesion. Too slow and you will get melt down through the base. I would try brushing the base coats on and sanding well before spraying the top coats. That would be a good way of testing the thinner as well. If it doesn't brush on, the thinner may be your problem.

Leonard Neumann

Lt Col Tom McClain

I have never seen this problem. I have stayed with Brodak dope with Brodak thinner thinned 60/40 and get a great application almost all of the time except when the humidity is over 60% and the temperature dew point spread very close. I have no experience with Grip or cellulose thinners. I would stay with Butyrate and lacquer thinners like Brodak. If you use SIG, use Dupont 3608S to thin it. Clear Dope should be thinned no less than 50/50 initially for the first coat of clear and then thinned 60/40 for subsequent coats. Color dope should be thinned 60/40. It will go on better and lay down well. Use clear to build up your base at first before using color. This will keep the weight down. I usually put on 6 to 8 coats of clear on the silk or silkspan tissue with wet sanding with 600 paper after each 3rd coat. After I get the clear base where I want it I then put on no more than 3 coats of silver, thinned 50/50 with clear and then that mix thinned 55/45 with thinner. I sand after the first silver coat down to the last coat of clear and fix the imperfections that the silver reveals. Then I apply the second coat of silver and if I have prepared the base well, that should be it. I then wet sand the final silver coat with 800 to 1000 wet/dry paper and then mask off for the color coats. It should take no more than 1 maybe two coats of color to finish the model. Finally, I apply one coat of 50/50 thinned clear over the color, let it dry for one day and then finish with 2 to 3 coats of 60/40 thinned clear over a 3 day period. I might put in some retarder, no more than 10%, in the last two coats of clear to get a real glossy smooth final finish. You might not have to rub it out if the retarder works like it has for me.

Good Luck,