Acrylic color shift and shrinkage
GOLDEN Heavy Body Color and acrylic mediums provide a range of options to artists wanting to paint thickly. This video demonstrates two factors that should be considered when working with these products – color shift and shrinkage that occur as acrylic paints and mediums dry.
Color Shift: The binder used in acrylic paint appears milky or white when wet and clarifies as it dries, resulting in a darkening of colors. The color shift may be less noticeable in lighter colors (like Benzimidazolone Yellow Light) and more noticeable in darker colors (like Ultramarine Blue).
We generally recommend mixing your acrylic colors a step lighter than you desire, so when it dries darker, it will be within the range you need. It’s often helpful to apply a little of your color or mixture and let it dry as a test to see if it is still the color you desire. Another way to compensate for this value shift is to add a small amount of Zinc White to the color, which is a transparent white. Titanium White can also be used and will result in a lighter and more opaque color.
Shrinkage – Acrylics dry by the process of evaporation. As the water releases from the paint, the acrylic polymer spheres coalesce and eventually fuse to form a continuous film, shrinking in volume. In the video, you can see the thickness of the application decrease and the edges pull in as the mixtures dry and shrink. The thicker products are applied, the more apparent these changes will be. A thicker application of acrylics will also have a longer drying and curing time.