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Paint Thining Question Scenery and structures
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Super User 772 posts RandallG Super User 772 posts
RandallG

The various formulas for making a thinner all call for a small amount of retarder. What would happen if you don't use the retarder? Is there something else you can use?

 
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Greg Amer gregamer Regular poster 496 posts
Greg Amer gregamer

Flow improver

When I’m airbrushing acrylics, I usually use a drop or two of Vallejo Flow Improver. If you don’t use it, your airbrush tip may dry a little more quickly. In my experience, some paints flow nicely without any thinner or retarder including Vallejo Air and Golden High Flow. MRH publishes an acrylic thinner formula, which I believe is pretty much Createx High Performance thinner with flow improver. In my experience, I airbrush almost every day, and use so little thinner that making my own blend doesn’t make any sense so I generally use Createx HP thinner and a drop or two of Vallejo flow improver.

 
Greg Amer The Industrial Lead

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2tracks Regular poster 320 posts
2tracks

Thinner....

I don't do near the airbrushing that  Greg does, but I knew I wanted something when airbrushing Acrylic paints, so I ended up with Testors Universal Acrylic Thinner. Too new to the airbrush techniques to know about the flow improver, but sounds like a good idea.  Greg, do you find that, with different brands of paint, you use different combinations of  thinner/flow improver?  Randall mentions retarder, is that the thinner or flow improver?

Jerry

"The Only Consistency Is The Inconsistency"
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joef MRH Founder 17,486 posts
joef

water-based paint vs solvent paint

The idea with the thinner formulas is to make spraying water-based acrylics a lot more like spraying solvent based paint — in other words, avoid the toxicity and health concerns, yet get similar paint application benefits. Solvent based paint tends to airbrush on very smoothly, level out nicely, grab the substrate well, and dry more slowly. Water-based paint tends to not airbrush as smoothly, not level out as nice due to the surface tension of the water, not grab the substrate quite as well, and they dry more quickly — sometimes the paint can be almost dry even before it hits the model. Due to the fast drying of water-based acrylics, the paint can dry on the airbrush tip, clogging it. It’s called tip-dry and faster drying water-based paints are especially prone to it. The retarder helps alleviate the tip dry problem straightaway, and it also prevents the paint from being almost dry when it hits the model, plus it gives the paint more of an opportunity to self level before it dries. The flow enhancer helps solve the water surface tension issue, so the paint acts more like solvent paints. Finally the HP thinner additive butyl cellosolve also improves flow and gives water based acrylic paint more of a bite into the substrate, again more akin to how solvent based paints act. If you have experience spraying solvent paints, all three ingredients: retarder, flow enhancer, and butyl cellosolve combine to make spraying water based acrylics act a lot more like spraying solvent paints without the harsh chemical downside. That said, all atomized particles created when spraying paint need to be treated with respect, so wearing a shop mask over the nose and mouth should be routine. A spray booth with a fan that sucks the excess spray away rather than leaving it linger in the air also is quite helpful.

Joe Fugate​
Publisher, Model Railroad Hobbyist magazine

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2tracks Regular poster 320 posts
2tracks

@Joe

Great information,  I can definitely use that, thanks .....

Jerry

"The Only Consistency Is The Inconsistency"
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