View Full Version : Synthetic Resin Varnish
04-21-2002, 06:14 PM
Is it okay to use this kind of varnish in a medium? I have a bottle that says the ingredients are cyclohexanone resin, acrylic resin, and mineral spirits.
04-21-2002, 09:41 PM
Dave, polycyclohexanone resins are one of the better classes of synthetic resins in terms of optical characteristics and they have low viscosity which should mean the medium will have a tendency to level out (which of course a varnish would be designed to do so that it does not easily show brushmarks). Acrylic resins have relatively poor refractive indices and I imagine they would select one which would also level well. At a guess, the acrylic in the mix is there to act as a plasticiser in the dry film as polycyclohexanones get very brittle with age.
If you care about longevity I would do at least some long-term testing before using it extensively. Compared to mediums containing natural soft resins it won't quite match their optical properties but it will likely have other advantages: yellowing less and becoming insoluble over time, as oil films should be ideally (which, paradoxically, means it probably isn't suitable as a varnish!) Try a test with some paint and see how it goes; it should work fairly well optically, giving at least reasonable depth, and it might have beneficial handling characteristics. It should also dry quickly because the PCH resins are fast oxidisers.
04-22-2002, 03:15 PM
Thanks. You sure know your synthetic resins.
04-22-2002, 07:26 PM
Yep, I can look up reference books with the best of 'em :D
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