paint problem. what did I do wrong?

[JohnU]

I'm new to airbrushing. Trying to figure this out. I mixed Tamayia primer 50% with lacquer thinner.  When I spray it on it looks OK. After about a minute it started blistering like the picture below.

What am I doing wrong?

[Captain Poison]

You applied primer-sealer first? That could be one cause for blistering.

[thibaultron]

Was there a finish already on the wood before you sprayed? Also, Tamayia paints are not true lacquers. Try spraying a sample of wood using the Tamiyia brand thinner. It looks like a reaction between either an existing coat, or the chemicals in the paint/thinner mix.

[bartley]

Did you use Tamiya thinners or some other brand?  There looks to be an incompatibility somewhere here.  As Ron points out you should use their thinner even though it is quite expensive

John

[AnobiumPunctatum]

You have to use Tamiya colors with the Tamiya thinner of Isopropylalcohol (I recommend the thinner).

I think that you use a wrong pressure and distance by airbrushing. It seems that the color was dry, if it reachs the model.

If you new using an airbrush I think i's a good idea to do some tests and practice on white paper of scrap before you start on your model.

[Jaager]

1 hour ago, AnobiumPunctatum said:

I think that you use a wrong pressure and distance by airbrushing. It seems that the color was dry,

I find lacquer thinner to be so awful, that I would not consider using it for anything except for where it is a requirement.  That is, with lacquer.

If isopropyl alcohol is an alternative to Tamiya thinner, then part of the problem with using lacquer thinner may be because it evaporates more quickly than Iso-OH.  Some of the paint may have gone on near dry.  It also may have done bad things to a primer, if one was there.  Organic lacquer thinner is so noxious, even the Green alternative, I do not use it for anything but brushing lacquer (on paper patterns).  It is bad enough to be around just from evaporation,  I would would not aerosol it mechanically unless it was in a glove box and the box was vented to the outside.

 

Here in the US, isopropanol can be had in several forms.  Maybe 50%, certainly 70%, and 91% and the difference is water.  I doubt that any of these will play nice with a paint solvent that does not crash when lacquer thinner is mixed with it.  Water and organic solvents are mostly incompatible.   100% (99.9%) Iso-OH is out there,  if not as easy to get. ... OK - Amazon sells it for about $40/gal.

[bartley]

2 hours ago, AnobiumPunctatum said:

You have to use Tamiya colors with the Tamiya thinner of Isopropylalcohol (I recommend the thinner).

I think that you use a wrong pressure and distance by airbrushing. It seems that the color was dry, if it reachs the model.

If you new using an airbrush I think i's a good idea to do some tests and practice on white paper of scrap before you start on your model.

Actually, there is more sec -butanol in their thinner than iso-propanol so I would stick with their thinner rather than try to use a substitute

[vaddoc]

Stick to the company thinners, they are designed to give the best result. They tend to be more complex than water and isopropyl alcohol I feel and the cost is negligible all considered. But most importantly, always test your chosen finish on scrap wood, not the model itself!

[Bob Cleek]

I ran into that phenomenon once when I mistakenly thinned a paint (brand forgotten) with acetone (like lacquer thinner) which was supposed to be thinned with alcohol. It wasn't a "blistering," which is when air or gasses expand beneath the drying paint coating. In my case, it seemed that the acetone caused the binder in the paint to "ball up" or "coagulate" when it hit the surface and when the acetone quickly evaporated and the coat "laid down," I was left with that that rough surface. In my experience, at least, was made up of solids, rather than being "bubbles" as with true blistering. Thoroughly annoyed with myself for overlooking the fact that I'd grabbed a bottle of non-oil-based paint I'd picked up somewhere thinking it was "the good stuff," I solved the problem by starting over with a proper oil-based lacquer and got the perfect finish I wanted.  ("l love the smell of solvent in the morning... smells like... like modeling!") Fortunately, I didn't have to sand the ruined coating off the model because, as Vaddoc noted, I always try out a paint on some scrap before applying it to the model. With all the so-called "safe and sane" water-based paint on the market these days you really can't assume that "paint is paint" anymore. With the low-VOC alternatives, you are usually stuck having to use their (grossly overpriced) proprietary paint thinners and conditioners. If one is going to use the acrylics, the best bet is to pick one brand, become thoroughly familiar with how it behaves, and stick with it.

 

Edited January 14, 2021 by Bob Cleek

[Ab Hoving]

This sound so familiar to me. When I was still building custom made electric guitars the painting proces showed all kinds of horrible effects. Imagine a body sanded untill it shone like a mirror with after spraying all sorts of blisters coming uit. The most horrible effects with reactions between filler and paint, paint and paint and anything that can cause disasters. It almost drove me crazy, although I have to admit that once the effect of spraying cause a beautiful, but unplanned crackling, like on an antique painting. Making guitars was a piece of cake compared to spraying them. In the end I just painted the bodies. More work, polishing afterwards, but no blisters any more...

[JohnU]

Thanks for the helpful replies. I now suspect there was an incompatibility between the sanding sealer(Shellac) and the lacquer thinner. 

 

I originally went to my local hobby shop for primer and thinner. They are normally very knowledgeable and carry quality supplies. I requested Tamiya primer and Tamiya thinner as advised on this forum. The clerk seemed to know just what I wanted and supplied my request.

 

Thinking this would ensure compatibility, I went home and eagerly did the recommended 50/50 mixture. To my surprise the paint suddenly turned to a large jelly-like glob on my mixing stick. I pulled the glob out with the stick and most of the thinner was left in the mixing jar.

Well! threw that mess out.

 

I then read the label directions on the Tamiya primer bottle. It clearly said to use "lacquer thinner" for thinning. The result is what you see in the picture.

 

As near as I can tell the primer they sold me is lacquer based and the thinner is water based. Though I told them specifically what I wanted it for. There was some strange chemical reaction. I will be making another trip there and I'll bring everything, including the glob, and see what they have to say.

 

Normally they are very good. I'm sure there was just a slip-up in what they gave me.

 

John

 

 

 

 

[Richmond]

Just a small point if you are using Tamiya acrylics use X20-A thinners and for Tamiya enamels use X-20 thinners

 

I use Tamiya acrylics all the time but use the (Gunze/Mr Hobby) Mr Color Leveling thinners which is great value as they sell in 400ml bottles  -  the results are superb.

 

I agree if you are using true acrylics such as those produced by Vallejo, MIG etc then as someone stated above you need to use the own brand thinners - them guys certainly know how make money!