By Suzanne W. Hellums
The isolation, or barrier, coat is simply putting a layer of clear, acrylic film onto your acrylic pigments. The need for this coat is to seal the artwork; before applying the final varnish. This “barrier” protects the acrylic pigments from damage – either from an accident, future restoration, if you ever want to redo your varnish layer (should the varnish layer ever be removed), and/or from ordinary handling. It is the professional thing to do for your acrylic painting. It protects your
pigments from dust and grime that can build-up over the years, in the varnish layer.
There are acrylic polymers created with these issues in mind and are created to bond with acrylics. This creates a barrier, so the underlying acrylic can be permanently sealed and undisturbed. Once the isolation coat is cured/dried, a final varnish coat (matte, gloss, etc.) can be applied without worry about what happens to the painting throughout its life. Varnish coats tend to attract dust. It isn’t uncommon for art restorers to remove varnish, to recoat a painting, down the road.
Acrylic paints are extremely lightfast. It is best to assume your masterpiece is going to be loved and exposed. To protect the acrylic for generations; it helps to give it longevity with this coat of protection. One of my favorites is the Liquitex® Gloss Medium and Varnish diluted with 20% purified water. I will use a gloved hand and gently rub this onto/into my cured acrylic paintings. I allow for the barrier/isolation coat to dry completely, before adding the final varnish coatings. This allows for my clients to pick what sheen they wish for their paintings to have (and it can be changed in the future; as the painting makes its way through the world).
Other ways to create an isolation coat vary on your preferred acrylic paint company. My current favorites are Golden® (their technical support is top-notch), Liquitex®, Daler Rowney, and Windsor & Newton. Each company has their own method for using one of their “glaze” products as an isolation coat. The barrier coat is an important way to insure the life of your masterpiece.