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Question asked 2017-08-03 10:55:12 ...
Most recent comment 2017-08-03 12:29:42
Oil Paint
Scientific Analysis
Varnishes
Paint Additives
Paint Mediums
Art Conservation Topics
I know that some varnishes such as Gamblin's GamVar and Golden MSA varnish have UV protection due to ultraviolet light stabilizer and filters. I presume that these are close to being transparent as it's used in a very thin layer of varnish.
Do you know of any process or product where similar light stabilizers and filters can be added to the oil paint itself via additions to a medium? Would this compromise the paint film? I was wondering if it would work to increase the lightfastness of the pigments and potentially could be present in greater concentrations than in varnish?
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Moderator Answer
(ssands)
Great questions. While the UVLS system imparts a slight yellow cast to a clear coating, as you correctly stated, it is essentially undetectable at the thicknesses a varnish is applied at, so you can essentially consider them clear. However, there are definite reasons you would not want to add UVLS to oil paint directly, nor ever blend a varnish containg UVLS to oil paints as a medium, or - at least in terms of our own MSA Varnishes - paint on top of them. That last point is something we touched on recently in an article published online:
http://www.justpaint.org/why-oil-painting-over-msa-or-archival-varnish-is-not-recommended/
The essential reason you should never add UVLS to oil paint is that it will inhibit the drying of the oils and cause them to remain sticky and uncured. The UVLS system not only filters out UV radiation, but is also designed to absorb the free radicals created in the process - however free radicals are precisely what is needed for oil paint to crosslink! It is as if you added in a permanent regenerative anti-oxidant which, well, stops oxidization. Not a good thing with oils and can cause major problems.
On a secondary note, we have found that UVLS has never been as affective when blended into a material versus applied up on top. - at least in the case of lightfastness protection. Unless one is using a very binder-rich system, you just do not get the same concentrations as a separate varnish layer can provide. But of course, because of the above issue, this secondary one is moot as far as oil paints are concerned.
Sarah Sands
Senior Technical Specialist
Golden Artist Colors
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