Spitting and Drying - what am I doing wrong?

Hi Fred,

It sounds like you've got some minor clogging in your nozzle, not enough to block the flow completely, but enough to alter the way the paint flows through. You haven't airbrushed some metallics lately have you? Put a few drops of lacquer thinner through it and see if this helps.

The other possibilities are potentially worse. This can also happen if the needle tip is burred or bent or if the nozzle has split or cracked.  If all is good, put a dab of metal polish on a soft rag and gently polish the tip of the needle. Fold the spot of polish over the needle and pull it through while rotating the needle. Do this a couple of times and then do the same a few times on a clean part of the cloth until no residue is deposited on the rag.

Assuming you can correct the problem, denatured alcohol on a rag will rip straight through Tamiya acrylics without affecting the styrene or an enamel primer. I don't know if it will affect MM acrylics though.

Thanks, Phil.  I'll try deburring the needle as it's the only thing I can think of.  After it was spitting the first time, I tore it all down and gave everything a good cleaning, but it continued spitting afterwards as well.

Any ideas regarding the gritty finish I'm getting?

Thanks,

Fred

Hi Fred,

To check the tip for burring, hold the needle at the xtreme rear end and let the tip rest on a soft cloth. Draw it backwards across the cloth, slowly rotating it sa you go. If it's burred, it will catch on the cloth.

The only things I can think of which might cause the grittiness is if you're using alcohol for thinner without a retarder, or perhaps spraying at too high a pressure or too great a distance. I usually airbrush Tamiya acrylics at no more than about 4-6 inches, usually less.

It may be more an issue related to low humidity rather than low temperature causing premature drying.

Thanks again, Phil.  I'll try that drag test this evening.

As for the thinner, I'm using Tamiya's own X-20A, so the retarder to solvent ratios should be spot on. 

The low humidity could very well be the problem.  It's been in the mid teens / low twenties with very low humidity and even though I paint inside, the window does need to be open to vent (though, I'm currently working on solving that problem).

-Fred

Phil has set you on the path required to fix your problems, so I'll just echo his concern that you are spraying from too great a distance. I spray 2-4" from the surface mostly, though I get much closer than that for detail work.

Hmmm...maybe I am spraying from too far.  I'm usually out about 12"-18", only because the table I work on has no leg room underneath.   It forces me to sit further back, rather than having the spray booth situated over my lap.  I have a few nights to decide whether or not to strip the current paint job (plus fix the airbrush), so we'll see what happens, come the weekend.

-Fred

Fred, that's the problem then. Acrylics dry very fast (though they "cure" much slower") and the paint is hitting the surface already dry. You'll need to move in closer somehow.