Varnish - a carrier, usually mineral spirits, and oil, hopefully Tung, and
cross linking resins, synthetic now, used to be things like rosin, amber,
etc.all cooked together so it polymerizes when cured.
Poly is a varnish with resins that form a stronger cross link then the ones
found in regular test. This makes it more resistant to damage which is both
a plus and a minus..
Never used a gel varnish of any type but I'd have to guess that an equal
build of gel or brush on varnish is going to provide pretty much equal
levels of protection.
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