[Tom Edgerton]

Richard and Sharon can speak to these issues way more than I, but having scientists in my extended family, I've absorbed a lot about product chemistry over the years.

Generally, the three things that will degrade artwork most over time are water, movement, and materials that are innately too alkaline or acid (not a neutral ph). Polyester eliminates a lot of these problems because, as has been said, it doesn't absorb water into the interior of the fiber, and thus doesn't move as much due to changes in humidity, and it's ph neutral I believe. There are a lot of traditional materials--paints, glues, etc.-- that were never chemically neutral/inert or crafted to be. So I'm not convinced that polyester is bad mojo just because it's man-made.

I worry a little about painting directly on it, because a polyester fiber is smooth-surfaced. A poly/ natural fiber blend might "grab" the paint a little better, but this may be just squeamishness on my part. Richard, would lightly sanding the poly before painting help any?

Also, here in the South, we get a lot of variance in humidity between seasons. I used to key the paintings tauter in the winter, but realized when summer returned, they'd get so tight they almost vibrated on the wall--it was a little scary. I imagine this extreme variance adversely affects the paint film. So I don't do it anymore, but I've noticed that my paintings around town gradually stop slacking off so much when they stay in one environment for a year or two and figure out "where they live."

Bill Whitaker advised that backing the painting with foamcore stapled to the stretchers would lessen the tautness variance, and I've found this to be true.

Sharon, thanks for the generosity in sharing your research.