Paint getting chunky when thinner applied

echolmberg

Hi guys!  I was going to airbrush the F-86D I'm working on in preparation for a metallic finish.  In a little mixing cup, I poured some gloss white and then I added some thinner.  Specifically, it was Testors gloss white (small square bottle) and low odor white mineral spirits from Home Depot.  I use that thinner all the time with my Model Master paints and I've never had an issue but when I added it to the gloss white, the paint seemed to curdle and it really clogged up my air brush.  I've had the same thing happen in the past when I added it to MM gloss black (in the round bottles).

What did I do wrong?

Thanks!

Eric

 

Eric, the mineral spirits that you used wasn't that "milky white" stuff was it?  I know there are some sorts sold that look like that.  I've used plain old hardware/paint store stuff (paint thinner/mineral spirits) for years without any issues, including lot's of the square bottle Testors paint.  That does seem odd to happen like that!

Gary

Eric - I can only speculate about the thinner type you reference, being the "low odor" sort. 

1. I've never used that one, I just use DuPont or other major brand enamel thinners from the paint store. I've thinned just about all of the commonly available model enamel paints with them, to include the little square bottles, never experienced any negative reactions.

2. Once at the hardware store I bought a pint of enamel thinner brand I had not heard of, it was an actual white color, I had no idea about that being the contents. It worked very poorly as an enamel thinner, it left the mixture of paint/thinner rather stringy, no matter how thoroughly I blended it with the little electric mixer from Badger.

3. I'd suggest using either a plain old major brand enamel thinner, or Testors universal thinner in the small red can. The low odor type you reference is what I suspect MAY be the problem.

Hope you get it sorted quickly.

Patrick 

Thanks to all for the responses! I should mention that the thinner I bought was/is clear. Maybe I shouldn't have called it a "white" thinner. It's clear through and through. Maybe I will switch to a different brand of thinner, perhaps one that isn't "low odor".  I always thought it was just weird that the only colors that have ever given me problems turning chunky were gloss white and gloss black.  Every other color has been perfect when it comes to mixing with the thinner I have.  It's a head-scratcher indeed!

Eric

Eric,

I have noticed what you experienced for many years now with MM enamels.  I think it comes down to basic paint formula; perhaps the elimination of lead and reduction in VOC content are the culprits.  Early on I noticed that MM flat red and chrome yellow turned whitish and then gummed up when contaminated with paint thinner, so I was careful to never return thinned mixes back to their bottles.  I have noticed recently their flat black seems to be like thinned Vaseline mixed with squid ink in the bottle.  It comes out kind of gooey and translucent, and requires many passes with the airbrush for complete coverage.  I used to be able to get coverage after only two or three passes; now it takes six or more.

Another kind of alarming thing I recently noticed was that my new gallon can of lacquer thinner does not seem to work very well with MM enamels.  I ususally use lacquer thinner for all my thinning needs when airbrushing, but noticed the flat black was not dissolving very well.  It also failed to clean my brushes which was totally unexpected.  The paints I was using were the ones I already had, so it must be that the formula for the lacquer thinner has changed (for the worse).

I fear in a few years we will all be using tap water with food coloring to paint our models!

I had a similar experience with mineral spirits from another large box retailer. When I first bought the thinner it was clear and worked like a charm. The other day I went to use it shadings and it was milky white and had large particulate that liked like snot. I had to totally tear down the airbrush and do a complete clean.

I have had lousy luck with that milky thinner, and will not use it again.  However, all that I had found was marked "paint thinner," not mineral spirits.  Ordinarily now I look for something that specifically says "turpentine" or "mineral spirits,"  If, however, it looked clear, that does not seem to be the problem.

However, fifty years of experience with Testors Enamel leads me to another issue.  Once the bottle seal is broken, it ages very fast, and not too many weeks will go by before it hardens to the point that NO thinner will dissolve it very well.  In spite of that, I love the stuff, so I will buy a new bottle of the major colors whenever I start a new kit.

Don, yeah I agree. And yet there are the Humbrol tins that I bought in the mid 1970s that are still good!