Up to this point, I have been painting on about anything I could find that was inexpensive. Since I haven't tried to sell my paintings, I'm ok with this. However it is time to switch to materials and techniques that will withstand the test of time.
The primary issue; will your painting crack over time? There are other issues such as yellowing and fading which can be addressed by the proper choice of materials which I will cover in another post.
So here is my take on the best practice.
The support should be stable and not flex since the paint film will become brittle over time. This means that if painting on canvas, the canvas should be glued to a stable support such as masonite, metal or plywood. If not, the canvas will flex with changes in temperature and humidity. Most of the rules of "fat over lean", "thick over thin" and "slow over fast" are all about not putting a brittle layer over a more flexible layer because when the flexible layer flexes, the brittle layer cracks. Remove the flex and most of these concerns are minimized.
Since I prefer a smooth surface, I will be painting on the panel without canvas. Here are my choices:
I am going to cut my panels out of Joubert Okoume mahogany plywood. Joubert is a french company and makes the finest quality of marine plywood that can be found. It is available just about anywhere boats are built. I will use the 5 ply, 6mm. I can get twelve 16 x 20 inch panels or twenty four 11 x 14 inch panels out of a sheet. This makes the cost very reasonable for a high quality substrate. Plywood is dimensionally stable and this plywood is free of voids and light weight. Why not hardboard? Simple, it is difficult to know what you are getting, are there chemicals in the wood process? At these sizes. I shouldn't have to worry about supporting (bracketing) the panels to prevent warping as long as I seal all sizes of the panel.
I will size the plywood using a ph neutral PVA size (seal the surface of the plywood). Hide glue has been used in the past, but it can absorb water over time and is messy. Gamblin makes a PVA size. Elmers glue is not ph neutral but can be made neutral with the addition of calcium carbonate. Four coats with light sanding with fine sandpaper between coats. Still want some tooth for the next layer.
The next layer sets the foundation you are going to paint on. Classically it is gesso made of hide glue and chalk (calcium carbonate). Today's acrylic "gesso" is better since hide glue does absorb moisture. I'm going to experiment with using lead white with some calcium carbonate included to both act as a extender and to neutralize the acidity of this layer. Why skip the acrylic gesso? For one thing, the bond between it and the oil paint is purely a mechanical bond. The combination of acrylic gesso and zinc white is known to cause lamination problems. Zinc white is very brittle and many painters avoid it because of this issue (me too). I prefer to avoid it and any issue with the bond between the acrylic and oil paints. I will add enough calcium carbonate to bring the ph of the lead white close to neutral, possibly slightly alkline. This should also give a nice smooth surface to paint on. I may tint this layer. (I might try Winsor & Newton Oil/Alkyd Primer)
This painting was my very first. It is called Tulip Abstract
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