Correspondence about Heat-set Oils, 2003
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The following correspomdence may interest anyone toying with the idea of using heat-set oils.

From: Sam Dauncey to George Debikey VP Director of Technical Services American Art Clay Co. Inc

Subject: Glazing with Heat-set Oils


I've enjoyed using Genesis Heat-set Oils for some years.

An old masters' technique with conventional oils was to use repeated dark thin monochrome glazes over most of the picture, selectively rubbing back the wet paint each time to previously dry paint. The end product was a painting with a very rich, dark background, good highlights (where the same area has been rubbed back after every glaze) and very subtle tonal variations in between. Colour glazes and small near-white highlights are sparingly added at the very end.

This seemed an ideal application of Genesis Heat-set Oils (since heating eliminates the need to wait for weeks between glazes and yet there is no rush to do all the work on one layer before it sets naturally).

I have a problem: Each individual glaze has to be thin enough for the detail of the under-painting to be clearly visible through it. Un-thinned Genesis paint is too opaque. One cannot use a ratio of more than 40% thinner or glazing medium to paint (i.e. 4 parts to 10 or 4 in 14) and even this is too opaque to spread thinly enough without scrubbing. The scrubbing seems to grind it into the underneath layer so that it is impossible to remove un-set paint with cloth or paper without damaging the already-cured layer beneath. Isopropyl alcohol had been suggested to me as a thinner (or, alternatively, to help lift the wet glaze off). It certainly dissolves the paint but also attacks the cured layer. Worse, there seems to be a chemical reaction that makes the paint gummy (apparently partly setting - I know that when I have used it to get very thin lines in conventional paintings, the residue on the palette has developed hard lumps after some days).

I suggested to Global Art Supplies Ltd (who is, I understand, your importers to the UK) that I should thin with your heat-set permanent or satin varnish (since these are, I presume, clear, can be mixed with paint in any proportion and will remain soft as long as paint). They advised me that the varnishes were too stiff but had no alternative suggestions. Can you help?

You are right about using the Heat Set Permanent varnish for Glazing. Many artists have been using it successfully for this technique. It has the advantage that you can use 100 %. Even though it is thick like the paint , once it is worked with the spatula it becomes soft and very spreadable. I would recommend using it without thinning if you can, but if you absolutely need to thin it, then the best is to add either Turpentine or Mineral Spirits. Both are solvents so they will evaporate and leave the paint as is. However, we are trying to stay away from such products because of toxicity. Best regards.


Thanks - I'll order some varnish and see how it goes.

Incidentally, if you are at a loose end, have a look at some of the paintings I've done with Genesis (and other media) you can jump to me from my picture near the bottom of the gallery of (a site I maintain). Thanks again.

I forgot to tell you that we are going to discontinue the Glazing Medium and we will replace it with Glazing Gel. You can use the Glazing Gel at 100 %. This product will be out by first of the year. I am looking forward to see your work on the internet this evening.


Tell me about the Glazing Gel. How much does it cost? How thick (and how thixotropic) is it compared to: Glazing medium? Thinning Medium? Heat-Set Permanent Matte Varnish?

I'm very taken with the rubbing out technique but have been very surprised at how difficult I have found it with Heat Set Oils (I expected it to be an absolute doddle). I've signed up for a workshop in June with one Mike Skidmore who uses the technique very successfully for portraits using conventional oils (in which I have no interest). He has had to develop his own fancy medium (Turpentine - 4 parts · Damar varnish - 4 parts · Thickened linseed oil - 2 parts · Venetian turpentine (balsam) - 1 part). As far as I can remember from his demonstrations, he applies his glazes very rapidly with a soft 2" or 3" brush.

I'm determined to prove that it can be done with the Heat-set Oils. Your Glazing and Thinning mediums are no good because you cannot use enough (40%). I bought a 4 oz jar of Heat-Set Permanent Matte Varnish but it is awfully thick. Help. Am I really going to be reduced to using a volatile medium?

Incidentally, I tried rubbing out to do some waves - partial success (see, go to the Gallery, click on my picture near the top and it's the second one on my page) Sam Dauncey

Hi Sam,
I have tried Genesis Glazing Gel directly over Gesso with the rub off technique. What I did is brushed the Glazing Gel all over the board and then with it wet I started applying the colors and rubbing out my painting. It worked all right. But not perfectly easy. The problem was that the Gesso absorbed the Gel and in a short time it became hard to glide the rag with which I was wiping of the color. I think that it would work if you apply a coat of glazing Gel over the Gesso and cure it. That will seal the Gesso. Then you can put another coat of Glazing Gel without curing it and work on that. I think that the second coat will remain wet for you to do the rub out because the Gesso has been sealed. Glazing Gel is not a liquid, it is just as thick as the Varnish. However, stir it well before you use it. That will soften it and you can spread it easily. Let me know how it works. I have not had the chance of trying it again yet. All the best.
George Debikey VP Director of Technical Services American Art Clay Co. Inc.
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