Two acrylic paintings are hung side by side. Both are appealing, but one has a much richer, more luminous appearance. The darks are more lustrous, light areas have more "life," and areas of transparent paint almost seem to glow with an inner light. How did the artist achieve this effect? Chances are, he or she used one or more isolation coats in creating the painting.
What is an isolation coat?
An isolation coat is a layer of clear acrylic that's applied to a painting prior to varnishing, and sometimes as the painting is progressing. An isolation coat is made from a mixture of soft gloss gel medium and water. The gel medium looks white initially, but dries crystal clear.
Here’s how to make and apply an isolation coat:
1. Mix one part water with one part Soft Gel Medium-Gloss Finish.
2. Stir gently but thoroughly to eliminate any lumps.(Gently is the key word here; vigorous agitation produces air bubbles.)
3. Brush the mixture onto the painting using a clean, wide brush with soft nylon bristles. Brush the mixture on gently and evenly, working in one direction.
4. Allow the first isolation coat to dry thoroughly before applying a second coat. (At least 24 hours if possible. More is even better.)
5. Apply a second isolation coat at an angle to the first coat to ensure good coverage. Let this second coat dry another 24 hours or longer.
6. Varnish the painting with a high quality acrylic varnish in the finish of your choice – matte, satin, semigloss, or gloss.
For best results, use only gloss finish soft gel for mixing an isolation coat. A matte formulation can cause dark tones in the painting to appear cloudy.
What does an isolation coat do for a painting?
An isolation coat gives a wonderful appearance of depth to a work. It enhances the colors, making the darks appear richer and the lighter colors more vibrant, even when those colors are opaque. And the luminosity of transparent colors is enhanced with the application of one or more isolation coats.
As if those weren't reasons enough, there are even more practical reasons for using an isolation coat:
It provides additional UV protection, which helps prevent fading
Helps protect the paint layer from scratches and abrasionsAllows the varnish coat to be removed without disturbing underlying paint layers, should the work ever need to be restored or cleaned
Offers extra protection from the effects of dust, dirt, smoke, and air pollution
The more coats the merrier
There’s no limit to the number of times you can use isolation coats in a given painting. You can sandwich paint layers between multiple isolation coats, if desired. (The renowned painter Edward Betts was a master at using multiple isolation coats in his acrylic paintings to spectacular effect.)
Just be sure to end with an isolation coat before applying varnish. Don't use an isolation coat as a substitute for varnish, however. You’ll still need to use varnish to ensure the painting is fully sealed and adequately protected.
Of course you don’t have to use an isolation coat; you can varnish directly over a paint surface with no ill effects. But if you take the time to apply even one isolation coat, your work will not only look better, it will withstand the test of time better, too.
© 2015 Lynn Edwards