Paint density is an important property to be familiar with in acrylic pouring, but it can be tough to understand, even for the most science savvy. So I’ve broken paint density down into just what you need to know in terms of acrylic pouring and how using it can be beneficial.
What is density?
Density is how much mass (the amount of matter in an object) a substance has in relation to its volume.
Paint density is expressed in specific gravity, which is the ratio of the density of the pigment to the density of water. For example, if a pigment has a specific gravity of 1.5, it is one and a half times as dense as water.
How can you find out the density of the paint you mixed?
Density = Mass/Volume
So to find your paint density, you need to weigh your sample of paint, zeroing out the scale to account for the container that you will use to hold the paint. You will also need to measure the volume of your paint. Then you can simply do the calculation of dividing the weight you got by the volume you got.
This is great to do when you are trying to compare your paint densities against each other.
What does paint density have to do with acrylic pouring?
As you’ve no doubt observed with oil and water, things with lower density will float, while heavier densities sink. The same is true for paint. Heavy paints like titanium white will sink to the bottom of your pours, while lighter pigments like yellows will rise up to the surface.
This post on Just Paint, published by Golden Artist Colors, has some great photos to illustrate the effects of density on acrylic pouring.
How do additives play a role in paint density?
Things like silicon oil lower the density of the paint you put it into and cause that paint to rise to the surface of your pour, often encouraging cell formation. This is why, when you use it, you only want to put it into one or two colors that you’re using. If you put it in all of the colors, you’ll uniformly lower the density of all of your paint and you won’t get the results you’re looking for.
Go forth and Pour!
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