Tarique,
You have quite a few questions, and I'll try to cover them all without having to write a book here. The advice Mary (I believe it was) gave you about using Fredrix oil-primed linen and stretching it yourself is good. The very best pre-primed canvas one can buy, of what I have seen, is from Hiromasa Funaoka, in Japan. I believe Gamblin is currently selling it in the U.S. Gamblin is at
www.gamblincolors.com. I suggest inquiring there if you are interested; however, the Fredrix product is very good, and I have no complaints regarding it. I've used it myself in the past. The difference between the two is that Fredrix uses a hide glue sizing, and Funaoka uses polyvinyl acetate, which does not expand and contract with changes in humidity the way hide glue (rabbitskin glue) does. Conservation scientists have determined that this expansion and contraction due to hide glue sizing is a major factor in the cracking of old oil paintings on stretched canvas, and thus they recommend PVA sizing as preferable.
Multiple paint layers are fine as long as your earlier layers do not contain a higher percentage of oil than the later layers (fat over lean), as oil undergoes shrinkage as it ages. More oil means more shrinkage, so when the lower layers shrink more than the upper layers, problems result. Ideally, we should know what paints are leaner and which are fatter, and which are somewhere in between, without anything added to them, and make our choices of what to use in what order based on that knowledge. This is what I do, but it is too complex an issue for me to explain fully in a short message. Adding a small amount of linseed oil to the paint of each successive layer will be fine, and will simplify things quite a bit. Use an eyedropper to add the oil to the piles of paint on your palette, and mix it in well with a palette knife, rather than just dipping a brush in a container of oil and stirring it into the paint with the brush, otherwise there will be too much oil in some strokes, not enough in others, and your paint layers will have weak spots.
Regarding varnish, there are several synthetic resins now on the market that are superior to damar. The best of them is Gamblin's Gamvar. It was developed by conservation scientist Rene De La Rie, formerly of the Metropolitan Museum, now with the National Gallery of Art, in Washington, D.C. Gamblin works with these conservators and scientists in the development of his products with an eye to archival quality. Note that I do not work for Gamblin, nor receive anything for recommending their products. I only recommend what I know to be the best, and I go to a great deal of trouble to determine what is, indeed, the best. If I don't know, I will say so. Gamvar is unlikely to ever yellow, and if it does, it can be easily removed with a mild solvent that will not take off any paint that has had more than two years to cure.
The chalking of darker colors you describe is common to certain pigments, burnt umber being the worst of them in that respect. Raw umber does it too, but not as badly as burnt umber. Caput mortuum violet also does it. Learn to get along without those pigments, and you will have less trouble with the chalky appearance when the paint dries.
Good luck with it.
Virgil Elliott
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