Canuck1

I am planning on spraying my finish dope colour. I was wondering what the mixture of dope to thiner is as well as the best pressure to set my spray equip at. I was also wondering if a retarder is required to slow the dry time down. Any thought would be appreciated.

Craig.

Phlip

I've used my Paasche H model (single action, external mix) airbrush with ~ 70 psi of air pressure, thinned about 50 - 50. It comes out OK, but it's slow going, and I've vowed that before I do it again I'll invest in a HVLP automotive touch up gun. That would change everything, I think.

Phil

LesUyeda

It is not possible to answer that question as to mix ratio. It depends on the thickness of your color dope. I have used 60 thinner to 40 color. Between 25 and 35 psi at the gun. I use a touchup gun for medium size jobs, and a full quart gun for 60 size planes. Smaller guns will tend to leave stripes. Retarder depends on the humidity the day you paint. If the humidity is high, and the dope dries too quickly, you will trap moisture under the paint.

Remember that dope is somewhat translucent, and you will take more coats to cover than you think.

Les

Canuck1

Les, thanks for the info. I started spraying the buterate this morning. It went on good and as you stated it takes a while to get the color to build up. I started on the vertical fin first, just to see. I noticed that I still have some pin holes in the fabric. Darn....it. I think I will go over the entire airframe with nitrate again, using my spray gun. I just finished the tail horizontal stab, and the spray on, looks fantastic, all holes filled in. Now i need to figure out the best way to fill those holes in the fin, any ideas?

Craig.

Canuck1

I seem to be chasing pin holes, or I think they are pin holes. I may just go ahead, paint my first colour coats and fill any pin holes after that. I am not to sure if that will be extra work or not. After the first initial coat, I should be able to spot the holes, fill them, then carry on with the other coats.

Craig.

LesUyeda

Do NOT, I repeat NOT, try to paint nitrate over butyrate. The Nitrate WILL eat the butyrate.

Take a brush, and touch up the pin holes with the butyrate color that you are using. The trouble with spraying, is that the air pressure blows the paint out of the hole you are trying to cover.

Les

Canuck1

Les
I think that is exactly what happend when I sprayed the paint on. I think I put too much on and it softened up the nitrate and blew right through. I need to make a very light tac coat first, then add more paint. Thoughts.

Craig

woodbutcher

Is the fabric Koverall?

I had the same problem and learned from threads here what I will do different next time. The main thing is I will brush the nitrate into the weave , even if I apply it fairly wet with a spray and some retarder.

If you still have most of the plane with just nitrate maybe you can try a spot brushing in some nitrate and shoot a little color there to see if it helped.

Good luck, I know I was really frustrated after shooting a lot of color and still having some pinholeing.

LesUyeda

Sounds like a plan, Craig. Proof of the pudding!!!!!!!!!!.. You will only know by experience.

Les

Canuck1

I added some talc to the dope and finished up the airframe and wings. The pin holes are all gone...........YIPPEE, I think. Next I will add a little colour base and see how she looks. Any small holes will be filled with talc and buterate. I think my first colour coats will be very light, not to cause to much loosening of the nitrate.

Craig