PREPARATION PROCESS FOR UNTEMPERED MASONITE WITH ACRYLIC DISPERSION PRIMER (Modern Gesso)
Begin with a ¼ inch thick piece of Untempered Masonite that is pre-cut to a desired size. It is important to note that it is recommended to prepare at least three 16x20” panels for use with the Language of Painting exercises.
We encourage you to carefully inspect each panel for defects prior to priming. If the board appears A-OK, you can proceed to prepare the support for the priming process. To do this, you will need a small elec¬tric sander or sanding block. We recommend a sanding grit of about 220. Grit too smooth will do very little while a grit too abrasive will aggressively scratch and mar the surface. We do not recommend sand¬ing by hand with sandpaper alone. Your hand is a very uneven surface and this unevenness will often transfer to your developing support. Be sure to use a sander or sanding block to ensure an even surface development.
We strongly recommend the use of safety glasses, a particulate respi¬rator, and a well-ventilated area to facilitate the support preparation process. Each step of your creative process should include every safety precaution possible.
You may notice that some Masonite will appear to have two differing sides—one smoother than the other. We have not observed any nota¬ble differences in the priming of either side.
Choose one side and begin to lightly scuff the surface with the sander. This gentle scuffing will remove any surface contaminants, minimize irregularities, and make the support more receptive to primer adhe¬sion. Do not apply too much pressure to your sanding device as heavy pressure may erode too much of the panel away.
Next, make sure that the edges of your support are not swollen from the initial cutting of the panel. The edges of compact hardboard are known to react this way. While this swelling may seem insignificant, applied primer will be adversely affected. The primer will run from the inclined edge as it is applied yielding very thin coverage. The thin primer will not withstand any later sanding procedures and will result in a compromised seal of the support and an uneven ground. We can correct this potential problem by addressing the swell now. This sand¬ing can be done by hand. Gently sand the edge until there is no sign of an edge incline.
When you are finished sanding, wipe off any sanding debris with a damp paper towel. Any remaining debris can adversely affect primer adherence. Place some newspaper under the panel or panels to be primed. Gather your gesso, a small plastic container, and a 2 to 3 inch flat utility brush. To develop a rougher tooth you can exper¬iment with using coarser priming brushes. Before applying any gesso, make sure that there is no moisture held in the panel from wiping off excess debris. Moisture will appear as dark patches on the panel. As the moisture evaporates, the appearance of the panel should become
Shake the gesso thoroughly and place a small amount into the plastic container. Apply a liberal amount of gesso across the surface. Establish an initial horizontal or vertical stroke direction. All subsequent layers will alternate direction to form a cross-hatch pattern. Be sure to cover the outer edge of the panel with each layer.
Our priming process will use 10 layers of gesso. Each layer is applied at roughly 12 hour intervals–one layer in the morning and one in the evening. Due to this length of time it may be a good idea to do groups of boards at a time.
Allow 24-48 hours after the final gesso layer application before sanding to desired tooth finish. To sand the primed surface—carefully remove excess newspaper from the edges by hand as shown. Again, we strong¬ly recommend the use of safety glasses, a particulate respirator, and a well-ventilated area for all sanding processes.
Gently sand the surface with a sander or sanding block until the desired tooth is achieved. You can carefully sand the sides to removes excess gesso and any remaining visible newspaper fragments.
In the same manner as our support preparation, you should sand the edges very gently by hand to minimize the risk to any thinly primed areas. Wipe off any excess gesso debris with a dry paper towel and that’s it. This surface is ready to go.