Making Canvas Boards  for Oil Painting.    By Don Finkeldei:  I use oil primed linen glued to masonite or board for paintings less than 24"x24".  In this article, I describe how I make them.

Extra Information :

When I painting plein air and/or small paintings less than 24" x 24", it's convenient to use boards instead of stretched canvas on stretcher bars.  Boards store easier and aren't as prone to be dented while traveling.   Canvas or linen stretched on stretcher bars should used for painting sizes 24" x 24" or greater.  See "Stretching Canvas on Stretcher Bars".  Boards over 24" x 24" can warp and get very heavy. 

I purchase large rolls of Belgium linen with a double oil primed surface of medium texture weave, although any type of canvas made of cotton duck, or Belgium linen (more expensive) with acrylic, alkyd or oil primed surface will work for oil painting.  Even boards with several coats of acrylic gesso will work fine (rough up the board with sand paper so the gesso won't peel off".  I happen to like oil primed linen.  Don't try to prime you own canvas unless you really know what you're doing.  Priming raw canvas is a fairly complicated procedure and takes a lot of time.

There are several types of board you can use.  Masonite (un-tempered because it's fairly acid free) or gator board (a hard foam center with laminated hard paper) is preferable.  For painting sizes of 16" x 16", 1/8" thick masonite is ok to use but above that size use 1/4" masonite because 1/8" masonite can start to warp.   There are two types of masonite, tempered and untempered. The untempered type is preferred because the surface isn't oily and it's acid free.  Masonite boards are easy to cut and cheap to buy.  You can buy a 4 x 8 foot sheet and cut it yourself, or your art supply store probably has pre-cut sizes you can purchase.  Google "gator board" to find suppliers that carry polystyrene foam core products. A supplier of many types of gator board in different thicknesses is http://www.artsupply.com/foamcore/gatorboard.htm

If you are using canvas or linen you'll want to use an acid free binding to glue the canvas to the board.  The most popular binding agents are a Soft Gel medium (I use Golden),  or a glue called "Miracle Muck" made by Raphael.   Most art supply stores carry them both.

Procedure (using masonite or gatorboard, Double oil primed belgium linen and Miracle Muck by golden:

1. Unroll the canvas or linen on the floor or a large table.  Place the pre-cut boards on top of the canvas arranging sizes so you get the least amount of waste.  Take a pencil, pen or magic marker and trace around the edges of each board leaving 1/8" extra on each side.  This will give you a little leeway when pasting the canvas to board.  The canvas can shrink a little during the drying process.  The edges can be trimmed up with a sharp razor blade or box cutter after the glue dries.
   
   
2. If using masonite, rough up the surface with sandpaper.  This will insure a good bonding of  canvas to board.
3. Paint the surface of the masonite with Miracle Muck.  Do this fairly quickly with a large 2" soft bristle brush (the type you'd use to paint a wall inside your house) in an even coat.  If needed, you can thin the Miracle Muck with a few drops of water.  Don't get it too runny.  It should be the consistency of a gel.
     
4. Quickly start rolling the canvas on the board staring at the bottom and work out all air pockets as you go.  I use a dry sponge to press out air bubbles and smooth the surface.  Keep pressing down the canvas until the glue starts to bind. This may take up to 5 minutes.  You'll want to make sure the canvas doesn't unglue anywhere, especially at the edges.  If a little curling or separation does happen you can lay a towel over the canvas and use an iron to re-activeate the glue.  Miracle Muck is heat sensitive.  Not the case for Soft Gel.