Finally got a Double Action and I Messed Things Up

If the paint ran under the mask it sounds like you didn't get a good seal on the tape which would be how paint got under rather than the thinness of the paint.

As far as I know siphon feed airbrushes do need thinner paint than gravity feed ones although I find it a bit hit and miss with thinning paint sometimes. I use a double action gravity feed brush and sometimes find I have to add some more thinner into paint that was fine the day before. 

Also paper absorbs paint better than plastic so thinning too much is hard to tell by experimenting on paper. I test out paint on an old kit to see how it will go on plastic. 

I f you are using MM acryl you DO have to thin the paint for AB. Even if extra thinned, it shouldn't have gotten under the tape if you sprayed very light thin coats. I'm thinking you went heavy causing the bleed thru. That's the beauty of a DA AB, the abilty to control the paint and air flow down to almost nothing coming out.

I have learnt a couple of things about spraying close to masking tape.

First make sure you burnish the edge of the tape, which is use the base of a brush to make sure the tape is pushed down as hard as you can.

Second you can use a quick run of clear paint (thinned of course) at the edge of the tape. This will fill in any run points with a clear paint so you wont get a colour run in there.

Third at the first run airbrush from above the tape so the air pressure is blowing the paint away from any possible holes in the tape. I have done it myself where you run the paint toward the tape and that will just push the paint under the tape if its not down all the way.

Hope these help a bit

Phil

Thanks very much for all the helpful replies.  I think it was a combination of many things as you all mentioned.  I think too I was a little too impatient with the thin paint expecting a better coverage.  I will use this "opportunity" to practice some sanding and fix up work on this one even though it hurts to look at a pretty good paint job with runs in it.

My only comment on spraying away from the masking line is what about when the distance between masks is pretty small?  I am thinking then a clear coat would be best.

John

Sorry should have been more clear on that. What I meant was you need to angle the brush so the paint is sprayed pver the edge of the tape not at it. If they are very close you can using very little pressure and just mist the area and build the colour up that way

Phil

Phil;

that makes sense.  My feeble mind was just having trouble getting around it.  It seems that I am thinking that the paint should cover quicker than it does.  Acryl seems to take a couple of coats at least.

I was down to about 12/10 PSI.  How low can you go?  I am going to experiment with the thinning and see if maybe I can get a little thicker paint.

Also, if the acryl is having some trouble sticking I was reading about a primer coat (which I do).  If the color won't stick, why would an acryl primer?

I'm full of useless questions today.  Thanks!

John

Ok to give the best answers I can, primers will pretty much alwasy stick even to photo etch, you dont have to use a special one for models I have used Automotive primer, just dont use a lot, you want a nice even coat.

Thinning on Tamiya paints I go 50/50 thinners and paint air pressure I get the compressor to 20 psi or so but as your using a dual action that is the max you can get. When you give it the air the more you pull back the more paint so you may not be pulling all the way back. But again practice, I use the inside of old cereal packets as they are grey like a lot of primers. Easiest advice is you can always add more paint you cant take it off

Keep asking the questions I know i still ask a lot on here

Phil

Good to know on the primer.  I have some acryl MM gray primer that I will use on the next one.  I have a 1/72 FW-109 and a 1/71 ME-109 from Academy.  I need more practice so I'll stay small scale and not spend too much to mess it up.

I may have been trying to get too close just because I "can" with the DA.  I think I'll mask, gloss coat to help seal and then try the whites and gray.  If only I didn't have to work, I could get good at this...

Thanks.

John

I hear you on that one. Go as light as you can with the clear you dont want to end up with a line, just try to mist it on

Phil

I finally had the chance to get back to this last evening.  I took the gloss white and just decided to see if I could spray it right out of the bottle.  Strange as it may seem, at 15 psi it worked fine.  Tip dried fairly quickly so I added just a couple of drops of acryl thinner, and then No problems.  Smooth line using Scotch Blue tape.

I think I was over-thinning the paint.  Gloss gray is next.  I will thin very lightly, but I loved the coverage right out of the bottle.  I guess it is really a hit or miss thing.

John

Not sure if this tip is needed anymore (!), but my wife has been a faux-finish painter for 10 years, and for critical masked edges she would heat up a palette knife using a candle, and then run it over the surface of the masking tape. The warmth of the knife would soften the adhesive further, whereupon she would press it down to form a more complete seal.

It was handy for working in smaller spaces, especially. Should apply to modeling as well, where a heat gun might be overkill!

This was using painter's tape (and her favorite brand). I figure if "the good stuff" needed a little boost, it was worth passing on.

;-)

James