On the Q&A page, Bethan writes,
I am interested in the various substrates used by 15-16th century painters- specifically wood. Which species of wood was commonly used and how were the panels constructed? I am assuming they had to be constructed very well in order to have lasted centuries without warping- a problem I am currently having. I am using birch plywood with Gamblin’s Traditional Gesso.
Bethan,
In the 15th and 16th centuries, artists typically used a local wood cut with the grain from the center of large trees. That kind of panel is hard to get these days. Italians liked woods such as poplar, cutting panels thick (up to an inch). Northern Europeans liked harder woods such as oak, which was usually cut thinner.
Panels were typically cut and planed to size, then seasoned for a year or more in the studio, with additional planing as needed as seasoning progressed. Modern authors often suggest finding seasoned high quality wood from old furniture or doors that might otherwise be discarded.
Warping is common with traditional gesso, since hide glue is very strong (stronger than most modern glues). I usually apply several coats of hide glue to the back of a panel to counteract the stress on the front. You can also gesso both sides equally. Some artists glue braces to the back of their panels, but that itself can cause problems. A carpenter can also construct a cradle using sliding dovetail joins which place less stress on the panel. You can find examples at www.realgesso.com.
I have found that birch plywood varies considerably in quality. It best to use furniture-grade or marine grade plywood rather than the stuff you find in any given home supply store. I also paint on tempered pressed wood panels (hardboard). These have been used since the early 20th century with mixed results. They are made differently now than they used to be, and the quality is variable. With care, it seems to work reasonably well.
Of course, the best panel material is high-grade aluminum honeycomb, but that’s incredibly expensive and hard to find.
Good luck!
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