How to Build & Plaster Masonite Panels

All Media – Needs No Frame

rbissett@meadowcrk.com
www.buildart.com

Equipment:

-Electric 7 ½” miter saw or miter box with hand saw

-Compressor and staple gun, or finish nails and hammer.

-Faster method:  don’t miter the corners.

-10” rectangular trowel, no serrations, notches or teeth.  11 or 12” ok.

-Orbital sander, Black & Decker, small, electric

-Vibrating sander

-Economy:  Use sand paper with block of wood.

-2 – Folding sawhorses, black, $19 each at Lowe’s, optional

-48” x 72” x ¾” Masonite panel for table top over sawhorses, optional

- 2 - Flea market sawhorses made with ¾” electrical conduit, optional, to finish
         edges more easily.

Material:

            Masonite panels, smooth both sides:

                        18” x 24” or smaller use 1/8”

                        48” x 48” use 3/16”

                        larger use ¼”

Cradle strips

            ¾” x 1 ¼” x 8’, primed, Masonite, at Lowe’s

            ¾” plywood strips are ok, too.

            Do not use regular wood of any kind, they will warp!

Middle support:

                        48” x 60” – 72” add one

                        48” x > 72” add two evenly spaced

Staples for gun:

                        ½” for 1/8” panels

                        5/8” for 3/16” and ¼”

            Elmer’s glue, yellow.

            Brush, 2” bristle, disposable

            Acrylic Gesso, thick not runny, Utrecht or W & N

            Joint compound, “Sheetrock”, thick not runny.

How to make the “box”….

1. Cut the panel to size, or have lumber yard do it.
2. Lay the strip flat-wise on the panel, mark for cut.  No ruler.
3. Miter the corners, or not.
4. Apply glue to top edge of strip
5. Staple or nail the panel to the first strip 3” on center
6. Mark and cut the strip for the opposite side
7. Do the two remaining sides, cut a hair short so they will fit
8. Two staples or nails in each strip corner joint, at an angle not 90*
9. With orbital sander sand the panel face and put a slight radius on the panel edges about 1/8.  Sand all edges of the cradle strips.  Sand the four corners of the cradle rounding them to about ¼” radius.
10. Remove all dust

How to finish…

1.      Apply one coat of Acrylic gesso with 2” brush, dip in water then in gesso, use figure eight motion.  Cover face of panel and four sides.  Let dry.  Use the flea market sawhorses to leave the sides easy to work on.  Some skip this step.

2.      On top of the panel with the trowel mix well four parts joint compound with one part of gesso.  For a 24” x 36” panel about one cup joint compound and ¼” cup gesso.

3.      Trowel the mixture on the four sides then a smooth even coat to the panel face no thicker than 1/8”.  Let dry completely.

4.      Using the vibrating sander or sandpaper and wood block sand the top and sides.  Sand the front corners of the panel down to the Masonite at the 45 degree position, exposing a thin line of Masonite to avoid chipping.  Gesso is ok, but no compound on those corners.

5.      Remove dust.

6.      Mix another batch of compound and gesso.

7.      Apply second coat to the sides as needed.  Texture the panel face:   leave the face area smooth for portraits, texturing only the other areas,  texture the whole panel for a landscape.  Use a skip trowel technique.  Let dry.

8.      Sand again exposing the corner of the panel’s rounded edges as before.

9.      Remove dust.

10.    Apply three coats of gesso thinned with water using the figure eight motion.  Sand lightly by hand after each coat and removing dust.

11.    Panel is now ready for linseed oil and the rub-out painting masterpiece!

12.  Or, apply two coats of acrylic Titanium White to seal the panel.

Variations…

1.      Glue canvas to panel face.  Cut the canvas a little larger that the panel.  Lay the canvas face down on a hard floor.  Use a rubber roller the apply Elmer’s glue to the panel covering the surface with an even coat.  Use lots to avoid bubbles forming later in the canvas.  Place the panel glue side down on top of the canvas.  Step on the back of the panel to insure contact.  Weight down with stacks of book.  Dry over night.  Flip over and trim the canvas ¼” back from the edge of the panel toward the middle.  Plaster the sides of the box up to the edge of the canvas.  Let dry and sand to make a smooth transition from canvas to plaster.  Apply three thin coats of gesso as above.  Good for rub-out or traditional painting.

2.      Bas relief.  Using the same plaster mixture you can build up areas of the panel 1/8” at a time, dry a day between each layer, ½” thick or more, then carve and shape with wood chisels, knives, sandpaper, etc.  Can also cut out shapes in Masonite, fasten them to the panel, coat with plaster and gesso.  Can cut a “flap” in the panel and bend it down and secure with wood blocks, glue, staples, etc., apply plaster and gesso.  Also, may build up relief with Pearl Paperclay, from Dick Blick.

3.      Water color and Acrylic.  Use five to one plaster mix.  Just one good coat of plaster on sides and on panel face, smooth and uniform leaving no dark areas where the panel shows through slightly.  Sand, etc.  Spray on clear gloss acrylic varnish or Damar varnish when done.

4.      Oils, acrylics, pen & ink, pencil, charcoal.  Use four to one mixture as for rub-out.  For charcoal varnish with acrylic or Damar, three coats.  First coat hold sprayer well back.  Second coat closer, etc.

5.      Hollow core door as panel.  18”, 24”, 36” & 48” x 80”.  Cut to length.  Rip a fill-in strip for the now open side, glue and staple both sides.   Sand and plaster as above.

Stapling panel to wood strip.