Question about panels

On the Q&A page, Bethan writes,

I am inter­ested in the var­i­ous sub­strates used by 15-16^th 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 15^th and 16^th 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 20^th 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!