The water-based acrylics (Polly Scale) state can be thinned by water, but i also read that you can use paint thinner instead.
Now, if paint thinner can be used, is the stuff sold in small quantities by various suppliers any different from a pint of “Night Train” generic thinner sold at a Walmart or similar store? And if not, then the generic is suitable for model paint thinning, right?
Just sorting it all out before i make really big mistakes…
Polly Scale is an ‘acrylic’ base paint - you can use either water or alcohol to thin it. I would not use an oil based thinner! Floquil Polly Scale is a very good paint, but you may need to thin it for airbrushing. Each color seems to be factory thinned to a different consistency(I suspect this may be due to the color pigments). A general rule for airbrushing is to thin the paint to the consistency of 2% milk. Mix your paint by stirring, do not just ‘shake’ the bottle and pour. I do ‘shake’ a bottle that has been around for a while, then stir it with a little battery powered stir machine. I pour it though a small metal screen(old lab item) to catch any large chunks that may not have mixed up. Clogging paint while airbrushing is a real pain…
If you use paint thinner to thin the acrylic paints, you are losing all the benefits (health and clean-up) of water-based paints. May as well go with enamel if that’s the case.
The alcohol seems to be the ticket, but I have to admit I STILL have problems with acrylics. I think they hate me…
As a long-time user of solvent-based paints, I had a difficult time adjusting to acrylics. Thinning with alcohol, as often recommended on this forum, resulted in constant problems with clogging, and the ratio of paint to thinner seemed to make no difference. Ditto with using the higher pressures often recommended here and on other forums, with persistent clogging, poor surface quality and irregular coverage.
After reading Testors’ own recommendations regarding both thinning and pressure, I found that distilled water (readily available at supermarkets) worked extremely well as a thinner, and in ratios varying from about 25%-95% water, depending on the particular job. Coupled with their suggested spray pressure of 15-20psi, all of the aforementioned problems were cleared-up.
The main drawbacks with this paint are, in my opinion, more difficult clean-up than with lacquer-based paints, and a much shorter shelf-life for the paint once it’s been thinned.
I just did some airbrushing yesterday and I still use what I refer to as the “Rosetta Stone of airbrush thinning”.
In the November 1998 Model Railroader, there is a chart that gives the proper thinning ratio for each brand of model paint. It also gives suggested spray pressure. Super useful chart, and I still use it every time I airbrush.
For PollyScale, the chart says to use either distilled water or Polly S airbrush thinner. The ratio is 80% paint to 20% thinner. The spray pressure is 20-30 psi.
I also agree with most of the posts here that enamels are easier to use for airbrushing. Easy to spray, easy to thin, and easy to clean up afterwards. But sometimes the perfect paint color only comes in acrylic based paints, so then you have to buck up and go for it.
The worst is painting large items with acrylic based paints. I airbrushed several G scale structures with Polly Scale D&RGW building cream. Beautiful color, but with so much area to cover and multiple bottles of paint to airbrush, it sure was a trick to keep the paint flowing and not clogging. Between bottles I would run a bottle of distilled water through the airbrush. Seemed to work OK.
The paint chart is also in Jeff Wilson’s “Basic Painting and Weathering Book.” I scanned a copy and tacked it up by the paint shelf.
Alcohol is OK but makes acrylics dry even faster. Distilled water doesn’t flash off as quickly.
As SW Chief mentioned, keeping the brush “wet” seems to help. I put a drop or two of Testors Acrylic Thinner in the bottom of the color cup before I add the color.
The advice so far has been very good. Personally, I use only acrylic paint, and generally don’t have any problems with clogging or drying too quickly. What I do, though, is thin the paint with a mixture of one part 70% rubbing alcohol to two parts water (I filter my own with a Katadyne filter – the one I use for camping trips). Then, after each color cup of paint, I spray a cup of soapy water through the brush into an airbrush cleaning station. Keeps things from getting all gunked up.