What is Masonite?

Kylee Kryklund, Pause, 8x10, oil on Ampersand Hardbord


To begin, the word "Masonite" is a brand name for "hardboard". It has been commonly known as "masonite" after the founder of the Masonite Corporation, William Mason, invented this wood product in 1924. These tempered hardboards in the '40s and '50s made conservators leery of paintings done on these now outdated hardboards due to the adhesion problems caused by the excessive oil on the surface. However, over 20 years ago, the high cost of tung and linseed oil forced U.S. manufacturers to change the way they manufactured hardboard.

Today’s U.S. hardboard is no longer made by immersing panels in oil. Instead, a tiny amount (less than .02 per sq ft) of oil (normally linseed) is applied with a roll coater and then baked and pressed at high temperatures. Most of this oil is flashed off when the boards are baked. This oil "tempering" is invisible and does not leave an oil residue on the panel that can cause adhesion problems, as did the outdated hardboard. The purpose of this process is to make the board stronger and less prone to warping.

Mark Gottsegen, in his book, A Manual of Painting Materials and Painting Techniques, writes that both tempered and untempered hardboard can be used successfully for painting. However, when artists call Ampersand, we always recommend using tempered hardboard because it will resist warping and the edges won’t fray as they sometimes do with untempered or standard hardboard. Furthermore, tempered hardboard creates a better seal with oil and acrylic primers so that the painted surface is protected from any potential discoloration.

Ampersand uses a tempered hardboard as the base for its Museum panels. After extensive research and testing, we chose a hardboard that is made through the Wet/Dry method. The Wet/Dry process method removes the lamella that contains many of the lignins and tannins that can cause discoloration in a painting over time. Through the use of water, this process leaches out many of the water-soluble chemicals and acids that exist in the wood, leaving a more inert surface than a solid wood panel. No additional additives are necessary for this process because the natural wood fibers are used for binding, resulting in a stronger, more uniform, and denser board. Ampersand Hardbord is primarily manufactured from Aspen trees that have more uniform fibers and have more of a neutral pH than that of other woods.

Lastly, our hardboard supplier does not use urea-formaldehyde glue in the manufacturing process. They rely on the natural lignin in wood for the bonding of the wood fibers, making our board environmentally sound.

MDF is sometimes referred to as Masonite or hardboard in lumber yards or even in art supply stores. Artists should ask if the panel is a true hardboard and not an MDF. Today there are very few true hardboard suppliers as the trend has shifted to MDF (medium-density fiber) panels that are less expensive to produce. However, the densities you can achieve in the hardboard process are difficult to achieve in MDF manufacturing without going to thicker, heavier panels. You will often see fiber raising and high levels of porosity in MDFs. All wood surfaces should be sealed with a good primer before gessoing or painting on them.

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