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Old 04-11-2002, 09:18 AM   #1
Karin Wells Karin Wells is offline
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Final Varnish




This info. comes from Gamblin about their Gamvar Varnish...

Quote:
Most frequently asked question: How long do I have to wait till I varnish my painting, 6 months, 9 months?

The answer is simple and complex. You can safely varnish when the painting is dry. But when is a painting dry?

Some paintings are dry enough to varnish in two weeks. Some are not ready for two years. If one paints thinly with fast drying colors using a fast drying medium, in a warm and dry climate, then the painting may be ready to varnish in two weeks. But if the artist has painted using Alizarin Crimson to make a half inch thick layer using poppy oil as a medium then the painting may not be ready to varnish in two years, if ever.

How to tell if a painting is ready to varnish is easy -- just touch it. If there are impasto areas, gently press your fingernail into that impasto. If it is firm underneath the surface the painting then it is ready for varnishing. We recommend painters using alkyd resin painting mediums wait three months before varnishing. Painters using an oil and dammar mix in their painting mediums should wait six months. But, if an artist has a painting that is only dry on the surface and that painting is sold, we recommend the artist varnish only with Gamvar Picture Varnish. Suggest the painter thin the Gamvar with approximately 20% Gamsol or other high quality odorless mineral spirits to make a very light coating. After application, the surface of the painting will have an even gloss and the colors will look very saturated. The thin coating of Gamvar will slow down the drying process but drying will continue slowly and no problems will occur as the painting ages.
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Old 04-22-2002, 10:45 PM   #2
Rochelle Brown Rochelle Brown is offline
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I've never done a final varnish. I like to use Kamar varnish which can be sprayed on when the painting is dry to the touch. It's quick and easy which is nice after all the painstaking labor. Does anyone know whether there are problems with this product?
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Old 04-23-2002, 08:54 AM   #3
Juan Martinez Juan Martinez is offline
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Rochelle,

I imagine that what follows is rather more than you were expecting. Sorry about that.

Kamar varnish (made by Krylon) is a synthetic acrylic resin varnish. Its main ingredient -- if my memory serves me correctly -- is a proprietary polymer resin called Paraloid 67. It has a relatively low molectular weight, but not as low as Gamar (I'll get to this point in a second). I have no knowledge on whether it is reversable or not. Of course, if nothing ever goes wrong with it, then who cares if it's removeable?

I'm not 100% sure about it, but I believe what happens with spray varnishes is this: the solvents in the varnish can penetrate the paint (microscopically) and therefore deposit the resin not only on top of the paint layer, but within it. Once it's in there, it ain't coming out -- ever. On the other hand, very low molecular weight (LMW) varnishes, such as Gamar (a synthetic hydrocarbon resin) or natural Damar (a natural gum? resin) both require much weaker solvents to dissolve them. Thus, the paint layer is left alone. When it comes time to remove the varnish and reapply it, there should be less of a problem with it because it hasn't penetrated the paint layer. Varnishes should be removed every 10 to 15 years, but practically nobody does that.

I have a gut feeling that if Kamar or its harder, high molecular weight alternative, Crystal Clear, do not all-of-a-sudden turn purple or something, that they should be alright. In fact, putting on a layer of hard or harder varnish and then going over that with the softer, removeable stuff, such as Gamar, might ultimately be the best protection for a painting. After all, once the surface varnish gets dirty and yellows slightly (both are inevitable) the softer one can be removed and re-applied. In the meantime, it serves to protect the hard under-varnish, which is itself protecting the painting.

A lot of horror stories exist about synthetic products so most traditional painters eschew them. However, so much research and improvement has been done in the field of synthetic resins over the past 15 years that they deserve a rethinking. Only use the best, in any case.

I contacted Krylon to ask them what was in their Crystal Clear and Kamar products--and they told me. So, since I was able to determine independently that conservators are "hopeful" about Paraloid, I have gone ahead and used these Krylon products. On the other hand, I contacted Blair to find out what was in their spray picture varnish and they would not tell me, saying it was "proprietary". So, I don't use the Blair products.

Robert Gamblin is generally forthcoming with information and works closely with conservation scientists. As such, I would trust the quality and longevity of his company's products.

On a final note to those who are adamantly tradition-bound: Using the so-called traditional resin varnishes such as Mastic and Damar can lead to just as many or more problems than those that exist, or are perceived to exist, with the modern synthetic varnishes. Mastic and Damar both embrittle rapidly, turn yellow, and become insoluble in mild solvents after a relatively short time. If the same is true of the sythetic varnishes (we don't quite know yet) then how are they worse? According to conservation literature and, of course, manufacturers' claims, the good synthetic varnishes shouldn't do those things, or if they do, it won't be as pronounced or as rapid as with the "natural" products. In all events, Gamar seems to be the best final varnish out there.

Finally, regarding molecular weight; it has to do with the levelling properties of the varnish. A high molecular weight varnish will always follow the contour of the paint once the solvents evaporate, no matter how many layers are applied. The LMW varnishes, including Damar, will have a levelling aspect to them that is more in keeping with the traditional look of varnish. This is especially helpful if you have paintings where the atmospheric illusion is important to its appearance. Otherwise, the HMW varnishes always make the viewer aware of the surface texture of the painting and thus of the picture plane. Just something to keep in mind, depending on the kind of painting you are making.

Hope it helps a bit. (Helps confuse, right?)

Juan
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Old 04-23-2002, 11:53 PM   #4
Michele Rushworth Michele Rushworth is offline
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What if I don't want the effect Karin quoted from Gamblin about Gamvar: "After application, the surface of the painting will have an even gloss and the colors will look very saturated."

I don't really like the look of a glossy painting (not to mention how hard it is to photograph afterwards!) and I try to carefully choose how much saturation I want in my colors as I paint and don't necessarily want to increase the saturation of everything later.

Is there a varnish I should use that won't add gloss and saturation?
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Old 04-24-2002, 02:06 PM   #5
Rochelle Brown Rochelle Brown is offline
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Dear Juan,

Thanks for that extensive information. It will be added to my list of valuable posts on this forum. Varnish is so important for a painting and in using the Kamar I hope to provide the best protection for my hard work and my client's valued portrait. Although, the one test that has yet to be done is the test of time.

Happy painting to you and all,
Rochelle
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