Acrylic paints incompatible? Tamiya and Model Master?

modeler1964 · Post by **modeler1964** » Thu Feb 26, 2009 7:52 am

It seems that I have read on various model sites that the formulations of these paints are very different and I have always only mixed like with like brands of paint to be safe. I know they can be painted over or under each other as separate coats but have never tried / dared to mix them because of some of the things I have read. Is there any truth to this? Have any of you ever tried to mix these two? Results?

photoguy · Post by **photoguy** » Thu Feb 26, 2009 11:47 am

They are different bases. Tamiya is alcohol, while the Testors is something else.

I tried thinning the Testors with my trusty denatured alcohol for airbrushing, only to see the pigment settle out of the mix, creating a gritty sludge in the bottom of my color cup

This, of course, clogged the brush really well, requiring me to tear it down and clean everything out.

Since then, I do not mix brands of paint together. I've never had any problem layering the two, just not mixed together in the same bottle.

Kylwell · Post by **Kylwell** » Thu Feb 26, 2009 11:47 am

Never tried mixing Testors with Tamiya (or Gunze). I've mixed Gunze & Tamiya without issue.

Alvis 3.1 · Post by **Alvis 3.1** » Thu Feb 26, 2009 12:18 pm

Testors and Tamiya acrylics are not compatable in my (or most of my customers) experience. The usual reaction is lumping. clumping and basically a curdling effect if you mix them together. If you paint them over top of each other, the effect varies as to how long the bottom coat is dry, and how heavy the top coat is, and how much of the brand thinner is used in the top coat. Washes, for example, cause the bottom layer to become wet again, and the clumping can result.

A common overcoat reaction is for the whole thing to crackle like a dry lake bed. Kinda cool if that's the effect you seek, not so much if you aren't.

My general advice: Don't let these two paints come in contact unless you want to experience new forms of swearing and learn how to strip acrylic paints.

Alvis 3.1

macfrank · Post by **macfrank** » Thu Feb 26, 2009 12:50 pm

photoguy wrote: I tried thinning the Testors with my trusty denatured alcohol for airbrushing, only to see the pigment settle out of the mix, creating a gritty sludge in the bottom of my color cup

I thin Testors Acryl with denatured alcohol all the time, with no problems. If the humidity is high enough, it makes the paint go on smooooooth. If the humidity is low, I thin the Acryl with windshield wiper fluid. Works great, either way.

Post by **TER-OR** » Sat Feb 28, 2009 10:29 am

I've painted them over each other - though usually with a thin layer of Future sealing the layers. They are not compatible in liquid form, though.

Romulan Spy · Post by **Romulan Spy** » Mon Mar 02, 2009 12:36 pm

I've never had problems painting one over the other, but never ever mix Tamiya directly with Testors (or PollyScale, for that matter.) I tried it once and it turned into a goopy puddle of goo.

As for thinners, I use Windex with both. Tamiya and Gunze are lacquer thinner friendly, while Testors is not. Gunze thinner, which is a mild lacquer thinner, is great with Gunze or Tamiya. It's great if you need to get the mix really thin for spraying fine lines and such.

fireworks · Post by **fireworks** » Wed Mar 04, 2009 11:40 pm

What's your ratio for thinning Acryl paints with windshield fluid? This would be for airbrushing right?

macfrank wrote:
photoguy wrote: I tried thinning the Testors with my trusty denatured alcohol for airbrushing, only to see the pigment settle out of the mix, creating a gritty sludge in the bottom of my color cup
I thin Testors Acryl with denatured alcohol all the time, with no problems. If the humidity is high enough, it makes the paint go on smooooooth. If the humidity is low, I thin the Acryl with windshield wiper fluid. Works great, either way.

macfrank · Post by **macfrank** » Thu Mar 05, 2009 12:30 am

fireworks wrote:What's your ratio for thinning Acryl paints with windshield fluid? This would be for airbrushing right?

Airbrushing. The ratio depends on the pressure and humidity, but 1 part windshield wiper fluid to 3 parts Acryl is a good place to start and 1:1 still works, but it'll really be thin.

Alvis 3.1 · Post by **Alvis 3.1** » Thu Mar 05, 2009 3:20 am

I find the ratio is dependant upon the specific paint, as some are a little more thin than others, gloss versus flat, and of course, how old the paint itself is, a half used bottle tends to be thicker than a new one fresh from Testors.
I try to get my paint to about the thickness of milk, but i grew up around Jersey cows, and their milk is about the thickness of heavy cream. My first tries tend to spatter like ceiling spackle. Better to be a little too thick than too thin though, as long as you were testing it on something other than the model. You can always thin it a little more, but it's way hard to thicken it back up again.

Alvis 3.1

macfrank · Post by **macfrank** » Thu Mar 05, 2009 9:37 am

Alvis 3.1 wrote: You can always thin it a little more, but it's way hard to thicken it back up again.

If that happens, and you're using an acrylic paint, you can thicken it with Future. Within limits, though. Otherwise you end up with tinted Future.

fireworks · Post by **fireworks** » Thu Mar 05, 2009 2:33 pm

What about windex? Actually somewhere else on the forum someone was saying that the ammonium 'eats' the paint and it's the alcohol that is doing the thinning. Is this true? I'm getting a headache trying to figure all of this out...

macfrank wrote:
fireworks wrote:What's your ratio for thinning Acryl paints with windshield fluid? This would be for airbrushing right?
Airbrushing. The ratio depends on the pressure and humidity, but 1 part windshield wiper fluid to 3 parts Acryl is a good place to start and 1:1 still works, but it'll really be thin.

macfrank · Post by **macfrank** » Thu Mar 05, 2009 2:44 pm

fireworks wrote:What about windex? Actually somewhere else on the forum someone was saying that the ammonium 'eats' the paint and it's the alcohol that is doing the thinning. Is this true? I'm getting a headache trying to figure all of this out...

Sometimes over thinking a problem is the problem. Experiment a little; just get an eyedropper and put in a few (count them) drops of well mixed but undiluted paint into a mixing cup - enough to get through the airbrush. Then start adding your solvent of choice (windex or windshield wiper fluid or denatured alcohol) to the cup. Start with maybe 1/3 as many drops of solvent as paint, then mix. The paint sloshing on the sides of the container should have the consistency of fat-free milk, like Alvis said. Basically, it should form a thin layer of paint as it runs back to the bottom of the cup. If it beads up as it comes down, it's probably too thin. If it's the consistency of chocolate milk, it's too thick.

Then spray your mixture (a very light coat) onto a test piece. If it beads up, it's too thin or there's too much water in the paint. If it starts clogging the tip, it's too thick or the air is too dry.