Supports and Grounds

- Standard Masonite Presdwood
[untempered]

The untempered material is light brown in color and is to be preferred to panels known as tempered Presdwood. The tempered material contains oily additions to the wood fibers, which make the panel more weather resistant but less apt to hold priming coats well.

The chief disadvantage of Presdwood is its tendency to dent and shred at the edges and corners when the unprotected panel is subjected to rough handling. The weight of the picture painted on Masonite is sometimes an inconvenience, especially if it is of substantial size--for example, 48 by 60 inches--and must be transported.

Lumber dealers sell other brands of hardboard that resemble the Standard Masonite Presdwood in color and size. However, many untempered hardboard products are considerably less absorbent than the Masonite and often seem to have a glassy resinous material mixed with the wood fibers or sprayed on the surface of the finished panel. If the Masonite Presdwood is not available and a substitute hardboard is used, its surface should be well sandpapered to insure as good a bond as possible between the panel and the ground coating which is to be applied.

Larger sizes (over 24 by 30 inches) of Presdwood panels should be braced with strips of wood glued along the four edges of the back of the panel; cross pieces may be added. The braces should be attached with glue, such as a hot hide glue or a cold polyvinyl acetate glue, never with nails or screws. Ordinary "C" clamps may be used to hold the strips overnight while the glue hardens. Contact cement can be used without clamps.

In actual practice many painters often omit the bracing until the picture has been completed. Then they brace the paintings that they consider successful, or they rely on the purchaser to have the panel cradled. However, the best practice is to brace the panel before it warps, even before the ground is on its surface. [pp. 114-115]