: Hey Brian,

: I guess you have a point but it seems to beg the question. What you said is
: like saying "Hey, Vodka's basically water with some other 'stuff'
: thrown in". Varnish and poly are as different as apples and oranges
: in my book, but that's just my opinion.

Not quite. It would be more like saying Vodka is basically a liquor, or a distilled alcoholic beverage, and there are many other liquors and distilled alcoholic beverages, like scotch whiskey, bourbon whiskey, and tequila. All have a high percentage of alcohol ( which might affect some varnishes!)

Brian is right in that there are MANY different varnishes made in many formulations, and from many ingredients. The ones we commonly call "varnish" are usually natural resins (frequently tree sap) which are dissolved in a mixture of solvents. A synthetic resin (and that includes epoxy resin) which was dissolved in solvents could be used for the same purposes (Varnishing)

The problem with disolving a resin in a solvent is that you have to have the solvent evaporate so the resin can precipitate, coagulate, or crystalize - or harden in some other way. A very thin varnish is mostly solvents. To get a protective finish you need to apply many coats.

The nature of the drying is such that the solvents on the surface evaporate fairly quickly, causing the varnish film to "skin" over as the upper surface thickens.

This causes a paradoxical situation: If the coating of varnish is relatively thin,(due to a high concentration of solvents) then the varnish layer left as a residue is dry and hard fairly quickly, but it is probably so thin that it provides little protection.

If the coating is relatively thick (due to a low conetration of solvents) then a "skin" forms rapidly on the top surface, which becomes a barrier slowing down the evaporation of the remaining solvents. eventually you get a lot of protection, but it takes longer to harden.

Ideally you would want a finish which would set up like epoxy -- that is it would harden throughout in a short period of time, even when applied thick enough to do some good. Two part urethanes which cure chemically, fall into this category.

Going back to a food analogy: there are a lot of recipes for cakes. Similarly, there are a lot of different types of materials used for varnishing. If you pick one you like and you stick with it you whuld be happy. If you are not happy, then you try another flavor, or a different brand of cake mix. And if you really want to get "basic" you can whip up a cake from scratch. Similarly, you can buy and dissolve your own varnishes, and mix in the necessary materials to get them to dry at whatever speeds you wish. If you want ttgo this route, check www.dickblick.com, Dick Blick Artist supplies and search for their dry varnish resins and solvents.

hope this helps

PGJ