Fred Ross has forwarded your question to me, so I'll see if I can help you.
I have a technical question; can you direct me to a reliable person? My question is: I have figured out that the reason my darks are sinking
in by the next day is that my ground (Claessens with the ground already on it) is too absorbent.
There can be other causes for the "sinking in" that you describe besides an overly absorbent ground. If the absorbancy of the ground were the problem, I would expect it to manifest itself in the lights as well as in the darks. The fact that you mention the darks as the problematic passages indicates to me the likelihood that you're using burnt umber in your darks. Burnt umber causes this phenomenon, and raw umber also but to a less extreme degree. If I've guessed right, and you are using umbers in your darks, the solution is to remove umbers from your palette.
I have not used Claessens' canvas for a long time, ever since they stopped using white lead as a ground, so I cannot say whether their current ground is too absorbent or not. However, the descriptions I've read of it have convinced me that it would not likely be as good as their older products that were primed with white lead. White lead is the best pigment for oil grounds. Zinc oxide is too hard and brittle, and titanium dioxide is too soft and spongy in oil binders. Mixed together, they work to compensate for each other's shortcomings to a degree, but I still consider them inferior to white lead oil grounds. Fredrix still uses white lead for their oil-primed anvases, and The Italian Art Store also sells lead-primed linen canvas. I would use either one of those before the current formulation of Claessens' canvas.
I'd be interested in hearing whether you've been using umbers in your darks. I have long since eliminated burnt umber from my palette, and seldom use raw umber any more either, due to their extreme absorbancy. When they dry, they read dull and matte, and any paint or varnish applied over them develops "dry spots," from having their binder sucked out of them by the umber.
I hope something I've said proves helpful to you.
Virgil Elliott
