Permanence of Gouache
I’ve been revisiting information regarding the permanence of my gouache paintings. I want to continue to be able, with a clear conscience, to assure my buyers that their painting isn’t going to fade away in their lifetime. Interestingly, the subject has only come up a couple of times in the last five years. Since gouache is watercolor, the information tends to cover both transparent and opaque. Permanence is allied with lightfastness. Here are some things I’ve found interesting:
Lightfastness… the ability of a pigment to retain its original color appearance under exposure to light. This is usually indicated as a numerical rating, from I (high lightfastness) to III or IV (low lightfastness), on the paint tube or in the paint technical information available from the manufacturer. Lightfastness is a crucial issue with watercolors, because the paint pigment is not surrounded by a protective dried binder (as in oil or acrylic paints) but is left exposed on the surface of the paper.
…in the 19th century watercolors acquired a market reputation for relative impermanence that continues to suppress their price today, and painters who admire this medium will make choices to improve its market status…
…The most stable painting medium is pastel, but modern lightfast watercolors are now more stable than oil or acrylic mediums.
…Industry labeling practice is to include a lightfastness rating on the paint packaging, and painters should only use paints that have a lightfastness rating of I or II under the testing standards published the American Society of Testing and Materials (now ASTM International).
The paints I use all have a lightfastness rating of I or II. And by using Kamar varnish, I’m adding an additional layer of protection for the paint itself. Of course, virtually all works of two-dimensional art should be hung or displayed where they don’t get extended periods of exposure to direct sunlight.
It’s Friday evening, and I’m hungry, so this is my contribution for the day.