Airbrush help - spraying gloss

[nickelplate759]

I need some advice.  I'm trying to airbrush TruColor paint, and am having difficulty getting an even gloss.  I'm not blaming the paint, as I've had exactly the same problem using the Modelflex acrylic gloss clear code.     The problem is getting the paint on wet enough, evenly, so that I get an even gloss across the entire surface.  What I get is some areas nice and glossy, and others not so much.

I'm used to putting on many light coats, so that I get good coverage with no extra buildup - but doing that yields a more matte finish.
My current workaround is to accept the matte finish I can produce reliably, and then use Testors Glosscote in a rattle-can.  I'm not happy with it, but it works.  I want to learn to use my airbrush to spray gloss.

Here's what I'm doing, and what equipment I'm using:

Paasche model V airbrush (external mix) with Medium tip.
20 lbs air pressure
Unthinned TruColor paint (which has a natural gloss).   
I'm spraying about 3" from the model. 

Thinning the paint more does not improve matters.
Spraying from further away makes the finish sandy.
Getting closer than 3" means that the coverage area is REALLY small, and I can't get seem to get it even with such a narrow spray.

Questions:
1.  should I user a larger tip - I assume this would flow more paint and spray a wider area?
2. should I use more or less air pressure?  What affect would that have?
3.  Is an external mix airbrush the wrong tool?  I have an internal mix dual-action brush, but am rather intimidated by it. I tried to learn to use it with both Polly Scale and Modleflex paints and found that it clogged almost immediately and was really hard to clean afterwards.

I'm more than willing to practice, but I am looking for guidance.

George

[LV LOU]

TruColor is supposed to be Accu-Paint.Accu-Paint is actually fairly easy to spray,since it dries so slow,really easy to get a wet coat,so you must be spraying it dry.The type of airbrush really isn't important,since all that's really necessary is a good,fine mist of paint.I'm not crazy about external mix,though.I use a single action Badger with at least a medium tip.I thin probably 30% or maybe a little more. I spray probably 6"-8" away.You need to be able to "read" the paint as it goes on.An N scale loco/car can usually be painted one pass,[full side covered with one coat..]with alternate,more concentrated,closer passes to adequately cover odd surfaces,back of cab,sill,ETC.The real trick is speed & spraying distance.The closer you are,the faster you have to move.It should look wet as it goes on,but should only get that look as the end of the spray pattern is almost completely passed over the object.Keeping it "wet" while spraying alternate coats and blends of the off ares is the key to success,you need to let it "flash",meaning,let it loose the driver,[thinner] just enough to let the next coat blend into the last,without getting runs..Most guys I see trying to paint simply don't put on enough paint fast enough to get a nice,even coat.If you watched me painting a shell,you'd probably be shocked at how long I take,and how fast I move as I paint.One thing about sprayguns,they can smell fear..LOL!!

[peteski]

TrueColor paint has more of an eggshell finish (not very glossy).

I don't have much experience with it, but it is supposed to be pretty much the same as Accupaint (which I have been using for years).  I use Badger 200: single action internal mix airbrush with a medium (or standard) nozzle.

I usually thinned Accupaints with their thinner (probably around 70% paint 30% thinner. I really don't have formulas written down. I just thin it until it feels "right".  I build up the paint by spraying semi-dry layer first, then progressively getting the next layers wetter, until the final spray is applied wet (all in a single spraying session). Then I might repeat the process if needed.

Are you spraying over bare plastic or over primed surface?

From your description I think that you need to open up the needle to increase the the paint volume. 20 PSI of air is probably ok (I usually spray at around 15, but I might be in a minority using low air pressure).  But if the paint is thin enough, you don't need a lot of air pressure for spraying.  I would also recommend using plastic spoons for practice.  They are very cheap and disposable.

As far as your fear goes, blame the problems on the water-based acrylic paints. IMO, those are notorious for clogging up airbrushes. I don't spray them at all.

[engineshop]

A few things I read in your statement:

"Polly Scale and Modleflex paints and found that it clogged almost immediately "
You need to strain paint (no matter which company) out of the jar and/or after you thinned it. I use ordinary paint strainer mesh from home depot.

"Spraying from further away makes the finish sandy"
The paint dropplets dry before the hit the model. The 3" is close but that is the furtherst distance I do.

"dual-action brush, but am rather intimidated "
I use the dual-action (a lot of air with not much paint) for corners and very detailed sections but other than that, I don't have good results with many thin layers. I have medium nozzle that covers the side of (a N-scale) model very nicely without going back and forth too many times.

"I want to learn to use my airbrush to spray gloss."
I use flat paint (Polly Scale) and use gloss clear coat. Works perfectly fine for me.

[dougnelson]

George:

I use mostly Modelflex, so I cannot speak to other paints, but I have found that some colors naturally have a gloss finish, and others have a dull finish, without any indication in the color name.  Here are a couple of thoughts:
- If you hold the brush too far from the model, the particles can dry or partially dry before they hit the model surface and this may inhibit a gloss finish.  Too close and paint will accumulate too quickly and be thick, so try spraying closer with less paint.
- You can spray painted models with Future floor shine (now called Pledge with Future Shine).  It is a diluted acrylic coating that is commonly used to spray models for a gloss coat before decaling to avoid silvering of decals on matte finish paint.  It sprays very nicely without thinning and should provide an even gloss coat.  Typically when I use it, I spray it on, decal, and then overspray again with matte or satin finish coat.
- You could also try experimenting with thinning your paint with Future, as it might provide a more even gloss or satin coat.

Doug.

[nickelplate759]

Well, continuing on with Tru-Color paint, more paint flow and keeping everything else just the same (20 PSI, about 2-3" spray distance) did the trick!
I was nervous about how much paint was going on, but it worked beautifully.

Thanks for all the advice.

George