Kevin O'Brien (kob@paradise.net.nz)
Mon, 12 Apr 1999 10:53:16 +1200
With varnishes & solvents there are a lot of nasties. Many early
varnishes had a natural resin base or lac base from insects and gum
turpentine, still used by painters, is a good solvent for most. It is
however believed to be both narcotic and carcenogenic. Most old formulations
used what was available; gum turps and urine were early industrial
chemicals. The printing industry has to produce coatings for high speed
mechanical transfer so their choice of resins and associated solvents may
not be appropriate for other purposes. The processes there are constantly
changing so what constitutes 'litho varnish' has to matched with the press,
the ink-water system, paper and the time it was formulated.
We should come into this century and look at the acrylic resins as modern
varnishes. There are Rohm & Hass products Paraloid B67 & other used by art
conservators. These use naptha ('mineral turps') as a solvent and are a lot
less toxic.
Kevin O'Brien
> Looking back, I seem to remember using something else besides the
carbona.
> Something I got from a printing house, I can't recall exactly; some kind
of
> a printer's thinner, a marketed product.
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