2014年2月9日 · Alkyd is a perfect Copal substitute when it use as a paint medium. As a picture varnish Copal and Alkyd have different properties (according to conservators). They said real copal varnish and alkyd varnish are not the same things. Most of modern “copal” mediums are alkyds. However, if you need copal as a picture varnish, you need real copal.

2011年10月11日 · I have some gum copal, not sure what kind or origin, that's all the container says. Thinking of trying to make some varnish with it. I found this recipe Take copal in powder, 1 oz.; essential oil of lavender, 2 oz.; essence of turpentine, 6 oz. Put the essential oil of lavender into a matrass of ...

2011年10月11日 · Colourless Varnish with Copal. —To prepare this varnish the copal must be picked; each piece is broken, and a drop of rosemary-oil poured on it. Those pieces which, on contact with the oil, become soft are the ones used. The pieces being selected, they are ground and passed through a sieve, being reduced to a fine powder.

2021年1月18日 · I still like Groves Copal varnish as a medium. Mixed with oil paint it works the same as his Santander-based varnish. In small amounts it gives paint great suppleness and precision. But I don’t know if I’d use it as a final varnish. Remember his copal varnishes are half resin and half drying oil (plus a little turpentine).

2016年3月13日 · With the proper set up it is pretty routine to make a Fossil Copal varnish. Copal resin also has resins that are not very old and are alcohol soluble, so it is necessary to select your grade. Copal resins needing to be depolymerized (bonds ruptured) by heating are classed as fossil. I think this also exists in grades of Manila.

2021年10月20日 · I have recently been experimenting with mixing in a bit of Copal varnish (10% - 20%) to my Colophony/Linseed oil varnish, to add a bit more hardness/toughness and to make the varnish a bit more wear resistant. The Copal varnish I am using is a very good one, made by James Groves. It is Very high in copal resin-content: 50% copal to 50% heat ...

2019年11月4日 · A mixture of 1 part of copal with 3 parts of naphthalene is taken, and then heated for an hour or two until complete solution has been effected. The mass is then transferred to a suitable still, when the naphthalene, being volatile, along with a little moisture and some oil of copal separated in the operation, are distilled off.

2018年4月29日 · The only replacement for Copal I can think of is Amber, but it is expensive, most varnishes prepared with Amber dry in 3-4 days because they are oil based (Walnut or Stand Oil), but they are quite taugh and durable if prepared with the real fossil resin.

2023年11月7日 · GamVar is a synthetic resin varnish that does not crosslink, or molecularly bond with the surface of the dried painting. And, that’s precisely what is required for an appropriate, final varnish. I have had very good experiences with GamVar, and I have had occasion to remove the varnish long after it had dried.

2012年9月16日 · DMF is the only solvent Ron, which can dissolve acrylonitrile resin and is able to remove the hardened copal varnish from old paintings. I know what I’m saying. Hermitage restorers are able to use turpentine and other solvents but in this case necessary choice is DMF only. Cyclohexanone – is an effective solvent for polyvinyl chloride resins.