[Tyler]

I won’t claim to be the expert but I can share all the info I’ve dug up across various forums and my experience. Cheap Acrylic grounds are often very absorbent due to high filler content (calcite, gypsum). This is not necessarily a bad thing and some people enjoy the tooth and way it grabs the paints off the brush. It can cause colors to sink in, especially darks. If you want to reduce sinking in the upper layers you can use an imprimatura and tone the canvas with a solvent rich wash. I like raw sienna for warm scenes and burnt umber for cool and will do a few layers to knock in the midtone values of the painting. This will dry in a couple days no problem usually. This is essentially just giving you a headstart on feeding the acrylic grounds oil. You could also just oil out the painting after finishing and the paint film has cured. That combined with a good gloss varnish should even out and remedy any dead spots. Another option is to use acrylic paints for your underpainting. Never use acrylic over oil, it won’t bond.

The general consensus on acrylic grounds archival properties is that oil over acrylic is not an issue as long as you aren’t using high zinc white pigments (zinc is a gray area and still being debated it seems but I would avoid pure zinc white.

Oil ground formulations often include pigment, oil, and alkyd in addition to the same fillers as previously mentioned. The fillers are what will give it tooth and prevent the slick feeling. I would agree with your assessment that fully dried oil layers would not form a chemical bond with the new layer. My understanding is the bond is mechanical in nature. If you paint indirect with multiple layers you could use chalk putty in your medium to provide better tooth for the next layers. I’ve been experimenting with this for reducing opacity of middle layers. I mull my own with linseed and Frederix marble dust. The old masters appear to have used this technique extensively so it should be okay, not that any of my work will need to survive 300 years anyway haha. They would also prime their support with lead white and chalk mixtures and let it dry multiple months before starting. Alkyds have helped reduce that time requirement today. In terms of which is better I think it’s personal preference and desired effect assuming you follow best practices to avoid problems down the road; fat over lean, thick over thin etc. Some people like smooth surfaces and others like toothier, if you are looking for fine detail smooth is good but you can achieve that with either grounds.

Caravaggio chirascurro technique on YouTube was a nice watch to understand some of what I’ve mentioned. Good luck!

• This reply was modified 2 years, 4 months ago by  Tyler.