Making Valazquez medium for solvent-free oil painting (marble dust, calcite, limestone medium )

And another thread on wetcanvas about that time
https://www.wetcanvas.com/forums/topic/how-thick-impasto-can-i-do-with-just-oil-paint/

The question is about painting thick impasto texture.  Hidden in there are similar feelings that calcite levels brush strokes like mentioned above, and this reply

A traditional, inexpensive way to extend and thicken paint is to use marble dust, a.k.a. calcium carbonate. This should aid drying. I haven’t really noticed a leveling effect on the brushstrokes — but then again, I tend to paint thin

Definitely something for me to experiment with.

One day.

I admit, I am not anywhere near ready to play with impasto yet.  But the experiments would take a long time to dry, like a year or two to cure enough to show defects, so it might be worth while to do some soon.


And later in this thread

Lately, I’ve just been mixing up some loose calcium carbonate powder with some of Art Treehouse’s water-washed linseed oil right on my palette to make the putty material that Tad Spurgeon writes extensively about on his blog (https://www.tadspurgeon.com/content.php?page=putty+tutorial). I’m pretty happy with this, as it’s easy to control the consistency, and it seems to make sense to mix only the amounts one needs for that session.

Regarding the putty, note that I’m not certain what sort of difference it might make to use artist’s refined linseed oil in place of the water-washed oil he recommends. Also, I understand that one should use a mask when working with calcium carbonate powder as it can be a respiratory irritant.

Again with this Tad guy.  I believe this is the current official link to get his book

Hmm... masks.  
I haven't found calcite to become airborn easily.   It sort of sits there heavy and resists being blown around by wind.  It seems to stick to objects if, say i accidentally drop a bunch because my hand shakes.  

But like all pigments, it's probably good advice to wear a proper dust mask.


When asked about using limestone calcite mixed with oil instead of some of Tad's more complicated recipes, this reply looks useful.

That is all there is to it – mix the powder into some oil until you get the texture you want. Test it by mixing into your paint and adjust the amounts as needed.

Limestone powder is a type of calcium carbonate as are chalk and marble dust. The grit size of the powders used will influence how they react in the oil. I prefer the way fumed silica behaves in an oil gel vs the calcium carbonate paste like materials. You can make your own silica gel as well by adding fumed silica to linseed or walnut oil, or you could try both to see what happens. As already noted, wear a mask when working with powdered materials. Fumed Silica will float in the air with the slightest bit of air movement so take precautions.

I agree.  

I'm glad I read The New Oil Painting book first as she makes it very simple compared to Tad.  I suspect the magic and alchemy of Tad's technique is part of why he is so popular among the technically minded.  It's not much fun if it's easy.

Fumed silica terrifies me.  It sounds like the opposite of calcite as it doesn't want to stick to anything.  It's supposed to feel like broken glass if one gets the smallest amount in the lungs.  I don't intend to buy any anytime soon as I don't have discipline to work with that kind of material.