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  #21  
Old 27-10-14, 03:58 PM
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Salamander Salamander is offline
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I don't know that I would varnish over them. but I'd certainly wait 6 month's to a year
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  #22  
Old 30-10-14, 02:59 PM
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Koo Schadler Koo Schadler is offline
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Hello,

There are two types of varnishes: (1) a retouch, which can be applied more or less immediately to a painting (as soon as it is dry to the touch); and (2) a true or final picture varnish. For the latter you must wait until the paint has more cully cured or polymerized. Within those two categories, there are lots of different options (both store bought and home made) and each has different attributes (matte, semi-gloss or gloss; varying drying times; etc.). Its a complicated subject.

For a retouch varnish, you could use shellac or various commercially made varnishes labeled as "retouch" (any made for oil will work on top of egg tempera). The plus of a retouch varnish is you don't have to wait; the drawback is that because the underlying paint layers haven't fully cured, the tempera layers cross link with the retouch varnish on top, and that makes the varnish difficult to remove at a latter date. Ideally, a varnish should be able to be removed (if it yellows, picks up dirt, etc) - nonetheless, many artist use retouch varnishes (due to time constraints) understanding that they essentially becomes permanent parts of paintings.

If you want to do a final picture varnish you are going to have to wait at least 6 months, as Salamander says. I believe all the tubed egg temperas are actually egg oil emulsions, with some percentage of a drying oil in them, and that can take a bit more time to polymerize than egg yolk. Six months to a year is probably wise.

I'm curious, Salamander - why do you say, "I don't know that I would varnish over them"? If I am detecting a hint of a bias against varnishing a tempera I would once again like to affirm that its perfectly okay to do so. Yes, the finish on a tempera painting is unique and beautiful - but the various varnishes seen on oil paintings (which can be replicated on a tempera) are lovely too, and no reason a tempera can't have a more pronounced shine and saturated appearance if an artists desires one (never mind the protection afforded by a varnish). As I like to say, if it was good enough for Van Eyck, its okay by me :-). Just wondering....

I hope everyone is well. Wish there were a little more activity on the forum, but hopefully its because we are all too busy painting.

Koo
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  #23  
Old 01-11-14, 02:06 AM
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Salamander Salamander is offline
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Hey Koo,
Im just relating my affinity for the natural et sheen.
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  #24  
Old 01-11-14, 11:31 AM
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Koo Schadler Koo Schadler is offline
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Understood, Salamander - it is a unique and beautiful sheen. As you know from my postings, I'm just keen to widen the aesthetic options of tempera.
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  #25  
Old 10-09-15, 06:38 PM
marknatm marknatm is offline
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I have exchanged e-mails with the folks at Gamblin concerning their GamVar archival varnish and it is OK to use on egg tempera. It has an odorless mineral spirit component and was developed to be removable. They also have a wax that can be mixed into the varnish that will add more matte appearance to the piece. The more wax, the more matte you get. I'm still experimenting with that. I have used it on a couple of my icons and I have been pleased with the results.

The only drawback to varnish I have found is that if I have varying degrees of tempered paint, then the varnish will be uneven. I think Koo may have mentioned this already. As opposed to using olipha (linseed and stand oil) which will fully saturate everything because of the thick application and give a nice even appearance when it finally dries.

However, I have abandoned the olipha for the GamVar because the olipha is very difficult to remove from a work.

Mark
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  #26  
Old 19-09-15, 03:33 PM
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Koo Schadler Koo Schadler is offline
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Hi Mark,

Thanks for your comment, and your other postings on the forum. Things get pretty quiet around here and its nice to have some activity.

I just recently undertook some research and writing on the topic of how to finish an egg tempera painting. Relative to your comment about Gamvar, while its true that (along with any oil paint varnish) it may be used on egg tempera, the challenge is getting such varnishes to behave over a true gesso ground and egg tempera paint layers (both of which are MUCH more porous, and hence more absorbent, than an oil- or acrylic-based grounds and oil or acrylic paint layers). I've played with several varnishes (Golden's, Gamblin, Natural Pigments, etc) and my experience has been they have a tendency to sink in when first applied. A sunken in varnish takes longer to dry (because it is not as well exposed to air and oxygen), and several coats may be needed to get an even finish. A matte varnish that sinks in is especially problematic, because the crystals added to some varnish formulations to make them appear matte will sit on top of the tempera while the varnish itself sinks in, which creates a frosted film over a painting.

There are ways to mitigate this tendency of oil-based varnishes to sink into tempera. A harder, true gesso ground (with a higher percentage of glue) has less absorbency; the longer a tempera is allowed to polymerize or cure, and if it is well polished, the less absorbent it is. The definitive solution is to apply an isolating layer over the tempera to decrease its absorbency. The isolator I've had the most success with is shellac - a very dilute mix of a platina, de-waxed variety works beautifully - but unfortunately shellac remains controversial, for reasons I'm not entirely convinced are accurate (a topic worthy of a whole other posting). I'm experimenting with other isolators recommended by various manufacturers and conservators which they feel would be better than shellac, including: various Golden's acrylic products; a caesin based spray on varnish; and a PVA size. I don't have a lot of time for this research but I've at least assembled all the materials and will try to get to them sometime this year. I'll post whatever I do (or don't) figure out.

I've met one person who doesn't seem to have this "sinking in" problem with oil paint varnishes atop tempera. Why, I'm not sure (he didn't know either) except possibly for the reasons given above. But the overwhelming majority of people who use oil-based varnishes over tempera seem to run into this problem. Conservators assure me that this doesn't mean one should not varnish a tempera; only that it takes a bit more consideration. Historically tempera paintings were often varnished, and certainly virtually every old egg tempera you see in a museum has been varnished at some point in its long history. The problem is that historical varnishes (mostly tree resins) are unstable, tend to discolor too much, are hard to remove, and thus are no longer recommended. The more modern, synthetic based varnishes (Gamvar among them) are much better. However so little contemporary painting is done in egg tempera, and most contemporary tempera artists do not varnish (in part for aesthetic reasons, but also because of the misconception that temperas aren't supposed to be varnished) that there isn't a lot of hands-on experience as to the best way to varnish an egg tempera painting (according to modern standards and practices). And while most manufacture's recommend their modern, synthetic varnishes as suitable for ET (rightly so), most do not have a lot of practical experience actually doing so. We ET artists who varnish are in the middle of trying to figure this out.

As mentioned, I just re-wrote my chapter on how to finish a tempera. I'm going to send out a PDF copy of it to my mailing list, but if anyone else out there wants one just send me an email and I'll forward it. It is by no means a definitive version of how to finish a tempera; just another stab at trying to clarify the subject.

Koo

Last edited by Koo Schadler; 21-09-15 at 11:06 AM.
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