Is there any particular reason why Regalrez 1094 is prefered as a varnish over Regalrez 1126? I gave up on using 1094 as a varnish a number of years back–I just don’t like how it handles, or how it’s really finnicky and tends to form an uneven sheen (and its high solubility means that you can’t really apply multiple coats to even out the sheen), and I don’t like how it tends to get tacky when you touch it, or when it gets too warm in my studio. Its glass transition temperature is so low that it can be above Tg at room temperature, on a warm day! That may not be a problem in the carefully-controlled climate of a museum, but for a painting that’s going to be hanging in someone’s house, and that may need to be shipped in the mail (how hot is it going to be in the back of that UPS truck?), it’s a problem.
So I went back to using dammar, because while its aging properties are inferior to those of Regalrez, it makes an aesthetically pleasing varnish that is easy to use with predictable results, and its Tg is high enough that it’s not going to get tacky and turn into a dust magnet just because you don’t have the AC turned on.
But doing some reading on varnishes, apparently Regalrez 1126 is a possible alternative? It has a higher molecular weight and a higher glass transition temperature than Regalrez 1094, but is otherwise chemically identical. Is there a reason why 1094 is (seemingly) preferred variant for varnishes?
-Ben
We forwarded this question to Gamblin and Robert Gamblin graciously responded with the following:
Ben
Interesting question about Regalrez. Sorry you have issues with 1094, thousands of us adore it. Just guessing from your brief description is that most likely your issues with unevenness are because of differences in the openness in the surface of your work. This most likely would be solved by selective re-varnishing in those areas, this the way that most painting conservators varnish.
Addressing why we use Regalrez 1094 for Gamvar rather than Regalrez 1126:
We are paint, ink, and medium makers, not scientists. We depend upon the research done by conservation science to identify suitable new materials for oil painting. The quality of their research and their objectivity is unparalleled. The studies that our work on varnishes is based on come from the early 1990’s. (New synthetic resins for picture varnishes, E. Rene’ de la Rie and Christopher McGlinchey, IIC Brussels Congress 1990)
At that time, Rene de la Rie, Christopher McGlinchey, and their team, mostly at the National Gallery in Washington, studied several modern synthetic resins, including mastic and dammar. Two Regalrez resins were included in the study: 1094, and 1078, but 1126 was not studied, perhaps it had not been developed by that time.
Important parameters of resins when used as picture varnishes, in addition to stability, are refractive index and molecular weight. Resins that are determined to perform the best in terms of light interacting on the surface of the art and color saturation have values closest to the natural resins such as dammar and mastic, and also linseed oil which all have similar refractive indexes and molecular weights.
And as you have identified, the molecular weight of 1126 is higher than 1094,so we then can assume that this resin would cause more light scattering at the surface of the paint which would decrease color saturation.
I hope you can find your way back to a more stable resin than dammar, but if not, Rene’s work also showed that including a HALS at 2% into dammar greatly improves its stability.
Hope this is helpful,
Robert Gamblin
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