I'm getting confused now, I agree with Tim, why the water? A thin layer of medium would do it, too. Perhaps the hot sun of Mallorca requires the water. So far I'm getting results from using a thin application of retouch varnish. I appreciate Tom Wise's advice anyway.

I think the water is necessary to make the emulsion when you shake the mixture. The emulsion allows the oil to brush into the dry oil paint surface like polish. In practice it brushes in so well that there is barely anything there. The water moisture left in the paint is so minimal that I have never heard of it being a problem.

I never enjoyed using retouching varnish. It seemed to attract dust, sometimes be unpredictable in drying and give the painting a brittle texture. I was so glad to find an alternative.

Please do test it and tell me what you think.

I'll do the test Tom in a small area of my painting. Retouch varnish does attract dust indeed.

An underpainting need not have its darks as dark as the final desired effect. The darks will have more depth if the underlying paint is lighter, and the deepest foreground darks subsequently painted with transparent paints in the top layer.

I would not recommend retouch varnish or any medium containing water for resaturating dried layers for painting over. A very thin application of linseed oil to the area to be painted into will do better. Wipe off as much as will come off with a lint-free cloth before commencing to paint. Enough will remain to accomplish the desired purpose.

Virgil Elliott

Your advice is deeply appreciated, Virgil.

I'm about to start applying color to an underpainting which I did with verdaccio, and which I plan to scan in the Forum soon. I intend to do the darks with glazes and the lights with opaque paint. Do you have any further suggestions?

Just one point about Mars black versus ivory black: Mars black is opaque, and thus will not give the depth that ivory black will. Mars black is good as a tinting black for underpainting because of its high tinting strength, but it is best not used in the color stage because it gives a dirty appearance to mixtures. Ivory black is more transparent, and thus will read as darker, especially if a touch of oil or medium is added to it. Opaque paints reflect light from the surface, whereas transparent paints allow the light to penetrate more deeply, so less is reflected from the surface to our eyes. Transparent colors also give cleaner tints than opaque colors in mixtures with opaque colors.