Recently started airbrushing primer on the Enterprise (Star Trek) using Model Masters white acryl primer. I thinned it using alcohol (91%) and started sparaying away. I had a real hard time getting the flow to start and when it did it started spitting out paint erraticly with clumps. When the paint dried, I successfully sanded down the bumps. I don’t want to be doing this again with the rest of the thing, it’s huge. Tips?
-Shawn
Clumping is a problem with acrylics. Make sure you stir the paint thoroughly. What air pressure are you using? How much thinner did you use? There are products called acrylic flow enhancer, found in art supply stores that help with it. I strain my acrylics thrugh an old nylon over the paint cup. This filters out any clumps that are in the paint. Sometimes the clumps come from paint build up in the needle tip and break free and wind up on the model. The flow enhancer will usually fix that. Iwata makes a can of oil that you sray your needle before assembling your airbrush… It helps keep the ab sealed and can keep the tip from having paint build up on it. Some guys use non stick cooking spray on the needle. I use neither. Try straining and thinning the paint to the consistancy of milk first. Spray using about 15-18 psi and see if it helps. This is the best I can do without knowing what ab you have and air source you use. These are the time tested guidelines that are battle proven over and over. Good for starting, but generally disregarded once you find the way that works best for you.
Drew
Hey Shawn, this is what Testors has to say about using their MM Acrylics - Click Here.
Have you tried it without thinning?
The paint might not like being mixed with alcohol… ??
[2c]
I seem to remember a recent thread with the same exact problem with thinning MM with alcohol. We never came up with a definite answer but were leaning to the vehicle or glycol ether not liking the isopropyl I believe. Tamiya acrylic thinner does wonderful with MM, and in the 250ml size it is only a dollar more than the 30ml size thinner so it is also economical that way.
I appreciate the suggestions, folks. The link to Testor’s was helpful. I tried it with out thinning and it is still rough but coming out a lot better and the rough finish is a lot “finer” than it was. I wish there was a soloution to this that didn’t result in me having to sand the thing when I was done.
-Shawn
Try lowering the pressure and getting up closer with the airbrush. Rough finish is sometimes paint drying before it gets to the surface.
Like Bill said. Also add some acrylic retarder to your paint mix to slow down the drying time and give the paint time to flow once it hits the surface.
FWIW I always use alcohol to thin MM acrylics and have never had a problem. I use 91% isopropyl alcohol and a couple of drops of retarder and it has always worked fine for me.