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Old 09-11-20, 18:27
David Dunlop David Dunlop is offline
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Join Date: Feb 2006
Location: Winnipeg, MB
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Default Wartime Varnishes

While waiting for paint to dry, and taking advantage of the last really nice warm weather here last weekend, I spent some time in the back garden reading up on vintage varnishes. I was frankly amazed at the amount of information that is available, and it is constantly being added to by research teams around the world involved in art, musical instrument and furniture restoration and preservation work.

In simplistic terms, a varnish consists of a solvent medium and resins dissolved therein, with or without the addition of lesser organic ingredients that influence the drying time, finish gloss or hardness/flexibility of the finished product. All vintage varnishes will colour, or darken, naturally over time and some compounds can be added to the mix to produce particular shades of yellow or orange with the initial application. Artists like Monet and Van Gogh, were aware of the natural darkening of varnishes and typically painted in lighter tones of paint to allow for the varnish darkening in the finished painting.

The three common solvents were linseed oil, tang oil and walnut oil, and if a faster drying time was needed, turpentine was used. The vast majority of resins came from conifer trees, pines and firs.

Where it got interesting was the locations for the most popular resin supplies - Malaysia, Indonesia and several of the smaller Greek Islands. It was also noted that the Canada Balsam Fir could also provide a good resin for varnish, but it had a tendency to darken rather quickly.

So it looks like, if the timeline for the fall of the above noted sources of resins during the early part of the war was compared to wartime wireless production, one would expect more late war wireless equipment to have varnishes made from the readily available Canada Balsam Fir, and these would yellow up, or darken, much more noticeably than the earlier war production items.

David
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