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Old 29-07-13, 01:40 PM
Koo Schadler's Avatar
Koo Schadler Koo Schadler is offline
Tempera Painter
 
Join Date: Dec 2003
Location: Alstead, NH & Zirahuen, Mexico
Posts: 317
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Hi Mona,

I've tried several different wax mediums, including Renaissance (as well as Gamblin and Dorland wax mediums). They all work well over tempera; in fact, of the many different sorts of varnishes I've tried, I would say the wax mediums are most in keeping with tempera's "nature", so to speak. What I mean by that is that wax mediums don't greatly saturate and deepen the dark values of a tempera painting (unlike some other varnishes, which can really darken the darks...although I actually liking my darks more saturated) and the shine imparted by wax is soft and not overly shiny – it is more akin to the "egg shell shine" that naturally occurs on an unvarnished tempera painting.

From what I understand, all the commercial wax mediums (whether the wax is derived from petroleum, as in the Renaissance formulation; or from bees, as with the other two) also contain some percentage of resin and mineral spirits. In short, they should be used with good ventilation.

If you apply a wax medium too soon to a completed tempera, you may lift up color. Michael Bergt recommends first finishing off a tempera painting with a layer of egg yolk medium thinned with water (what is technically known as a nourishing layer), and then letting the painting cure for something like 6-8 weeks before applying the wax. Banjie Nicolas recommends waiting even longer for a painting to cure - I think she waits about 3 months, to be on the safe side. Not sure of those exact wait periods, but suffice to say that you shouldn't wax your tempera right away - give it some time to polymerize.

Michael and Banjie are both experts at applying a wax medium - they get gorgeous surfaces. I've found that it takes some practice to apply it consistently (I'm still learning to do it as well as they do...). I use a lint-free, blue shop rag to apply the wax in a gentle, circular motion, working carefully to get a consistent application. Then, if necessary, I smooth it out further with delicate strokes from a 1 1/2" wide, flat, soft-haired brush. If you make a mistake, and the wax starts to set up a bit before you have the look you want, it can be adjusted and/or removed with OMS (odorless mineral spirits). Once you are happy with your application, let the painting sit overnight (perhaps a bit longer if you've applied a thicker layer of wax). Polish the surface once its hard and dry, to pull out a really lovely finish.

Regarding shellac as a finish: to be clear, there are people who object strongly to its use as a varnish on egg tempera. Some of the objection is aesthetic – shellac saturates the darks, and is shinier than a traditional tempera surface. However aesthetics are a personal decision and if a person likes the effects of shellac, well, its okay to like those effects.

However other objections to shellac are technical: shellac is brittle as it ages, and it can be yellowing. I’ve talked to many people, including conservators, art manufacturers and woodworkers about these issues, and feel they have been addressed. If applied thinly and to a solid panel, the brittleness is addressed (tempera paint also gets brittle as it ages, which is one of the reasons we work on solid panels). Regarding yellowing, its possible to buy "platina", very pale varieties of shellac that, if applied in a thin layer, impart no discoloration. From what I’ve read shellac’s color is stable: its doesn’t continue to get more yellow as it ages, but rather stays whatever color it was when first applied - and I have a 15 year old test strip of shellac that so far bears this out; there is not one bit of discoloration. In addition to working with a "platina" shellac, it is also important to use the "dewaxed" varieties.

Despite what I've just said, you can find people who vehemently disagree to shellac being applied to tempera - just as many people strongly feel that no varnish of any sort should be put on a tempera painting, even though many traditional tempera techniques employ varnishes. As mentioned, I think, if technical considerations are addressed, varnishing is a perfectly acceptable option.

Hope that helps, Mona. I'd love to hear how it works for you. Happy tempering - hope you are staying cool...

Koo
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