Acrylic Paints and Thinning Them for Airbrushing

by Grim on 2009/12/05

Acrylic Paints and Thinning Them for Airbrushing

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Acrylic paints and thinning them for airbrushing can be a daunting task, there is a lot of fractured information available online. Below is my take on it.

I use primarily Liquitex Softbody Acrylics in my studio. I do this because Liquitex makes paints with very good pigment load, light fastness, flexibility, and durability. I can also thin them with airbrush medium and use them in my airbrush.  The other acrylic paints I use in my studio a lot are acrylic inks, either Liquitex acrylic inks or FW-inks. Once in a while I still use inexpensive craft acrylics but only as a primer or undercoat or on a test piece, or concept, or when I need a very specific color and am lazy, too lazy to mix it up. I can also use the softbody acrylic when doing brushwork, so I only need to stock one kind of paint.

Terms
Pigment load: Acrylic paints consist of acrylic polymer emulsion (binder) and pigment. The ratio between binder and pigment is generally called pigment load. The more pigment in relation to binder the higher the pigment load.

Lightfastness: The ability of the paint/pigment to remain unchanged after prolonged exposure to light.

Thinning paints for airbrushing.

Types of thinners

Airbrush medium: A mixture of acrylic emulsion (clear acrylic paint, acrylic polymer), and flow aid (reduces surface tension, reduces tip dry). A good choice for most applications.

Distilled water: H2o. Reduces pigment concentration and color strength. Depending on substrate and amount of thinning required may be suitable for some projects.

My thoughts on thinning paints:

Acrylic paints are made up of an acrylic polymer emulsion(clear acrylic paint) and pigment. When airbrushing with acrylics you need to thin them somehow. If you were to add just water to them you end up stretching the acrylic emulsion to much. If you stretch the emulsion to much the acrylic paint has a tendency to crack and peel over time after it dries.  If you think about it, what happens when you airbrush is you are spraying out tiny little droplets of paint onto the surface of your artwork. Water has lots of surface tension, if you have a lot of surface tension in those droplets of paint you get spatter. Spatter will cause runs on the surface of your artwork. After all you have a water trap on your airbrush, why would you thin your paints with water? You could use alcohol it has low surface tension. Some airbrush artists use windshield wiper fluid to thin acrylic paints. I have a hard time recommending this. Windshield wiper fluid contains large amounts of ammonia and alcohol these will evaporate, what you end up with is a very thin layer of acrylic emulsion that is stretched too thin.

What you need to thin your acrylic paints with is something designed for this purpose, airbrush medium. What airbrush medium contains is acrylic emulsion and flow aid. Flow aid reduces surface tension which reduces spatter and airbrush clogging and also retards drying time, which keeps the tip of your airbrush needle wet during use.

While I could just buy acrylics that are already made for airbrushing, I would then have to buy 2 kinds of paints for my studio/shop. There is a benefit to this of course, I would remove some of the frustration I encounter on occasion when I don’t add enough paint or medium and clog up my airbrush, or make the paint too thin.

Acrylic Paints and Thinning Them for Airbrushing

{ 12 comments… read them below or add one }

Jay Tee Dee November 23, 2013 at 8:37 am

Through trial and error I have found that the best results in using acrylic tube paint in an airbrush is to dilute one drop of Acrylic flow improver into 9 drops of distilled water and add 2 drops of clear liquid drying retarder – then add paint to this clear liquid using a small brush and mixing thoroughly and keeping the final blend no thicker than milk. The ratio of paint can vary according to the actual colour you are mixing, acrylic pigment strength and textures can vary from colour to colour as well as from one manufacturer to the next. Mixing small quantities this way is great for getting accurate colour for artwork – but it can be time consuming. The paint retarder should be in the clear liquid form as it helps prevent tip dry without clogging the airbrush and none of these ingredients smell bad or have colour affecting qualities in these small amounts. Flush through with water after each cup fill and you can work for a long period without having to strip down until the end of your session. With good quality paint applied in thin layers you end up with a better intensity of colour which is waterproof when dry.

Mark E May 22, 2013 at 12:57 am

I have had pretty good luck thinning acrylic artist paints with either acrylic thinner for airbrushes or in a pinch I have had huge success with Pledge floor shine with Future. plus it gives the paint more of a satin finish then a matte finish. I have heard that the waxes in the future can cause issues but havent had any yet.

Xd12c April 11, 2013 at 7:35 am

What about Future floor wax? Actually, after looking at the bottle, it is now Pledge with Future Shine. I use it to thin my acrylic paints for hand brushing onto miniatures. As it is a liquid acrylic, couldn't it be used as an airbrush medium?

Charge5 March 28, 2013 at 12:37 pm

Great article! I have a lot of Montana GOLD sitting around and I'm interested in using it in an airbrush. My only thought is how quick it dries. Any advice?

Johnpipe108 February 1, 2013 at 7:48 pm

Airbrush Tip size relates to thickness of media; pre-mixed "airbrush colors" are ususally at a consistency to spray out of the bottle with a medium tip; fine tips require these same colors to be reduced using "airbrush medium" as stated. Other makers may use other names; "5608 Illustration Base" is the name used by Createx for the same type reduction media, for use with their 'Opaque Airbrush Colors." Some brands of reduction media may or may not be compatible with other brands of paint, depending on their individual formulation (I'm experimenting with Liquitex medium and Createx colors (what's locally readily available) and hope these two are compatible). I've provided complete info to our local art shop on this issue, and advised them to carry the Createx base as that is the color line they carry (they also carry liquitex base, but not colors). HTH, John

Bobby August 7, 2012 at 8:15 am

what makes acrylic craft paint grainy when airbrushing?

grimvisions July 25, 2012 at 7:02 am

Thanks for the question. What brand acrylic paint are you using? Some of the more inexpensive paints have irregular pigment sizes and are not well suited for airbrushing. When airbrushing you want to use a higher quality paint such as "Liquitex Softbody Acrylics".
One of the best solutions to start with is to just buy a premixed airbrush acrylic. This way you do not have to mix your own paint to start out with. there are several on the market.
You can also strain your mixed paint thru an old t-shirt or piece of panty hose to remove any particular matter.

Regards Grim

Africas finest February 4, 2013 at 2:09 am

Found out using warm water will help thin the acrylic paint better discovered when i had a blockage in my air brush also newbie to air brushing.

ZMAN55 July 24, 2012 at 5:17 pm

I recently bought an airbrush but I am having trouble with it already. I am using acrylic paint thinned with water so it is the consistency of milk, But when I try to spray it out of my airbrush it only sprays for a few seconds then it stops. In order to get it flowing again I have to bpull the lever back and forth a bunch of times and yet it does the same thing again….. A few seconds of paint, then nothing. Is my paint too low of a quality or am I missing some essential step? I have tried to thin the paint even more, but then it is too thin and it runs.

newdumbguy March 27, 2013 at 12:38 pm

the vent to the bottle is clogged, there has to be a way for air to get in the bottle for paint to leave

grimvisions August 30, 2010 at 3:34 pm

Kimily, Oops. I have done that as well, even when thinning them I have accidentally not thinned them enough and clogged it up something fierce.
Always try and get them about the thickness of milk. For now if you are just playing around and learning you can thin with water. But getting some airbrush medium would be a good thing. Also there are some decent pre-mixed airbrush paints out there that are reasonably priced.

Grim

Kimily August 30, 2010 at 3:19 pm

I made the rookie mistake of unpacking my new airbrush, filling the bottle with Black acrylic craft paint, start spraying and have nothing happen. First off… I didn't shake the bottle but once, of craft paint. Secondly… I didn't read a friggin then online about thinning with airbrush medium. Found out the hard way. Took me half an hour to get the thing unclogged!!! Only because I'm new at the airbrush, I'm sure it would have taken much less time if I was use to cleaning it.

None the less… lesson learned!

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