Popular Woodworking 2009-12 № 180, страница 57

Flexner on Finishing

BY BOB FLEXNER

The (almost) perfect compromise.

Gel Varnish

Thickness. Gel varnish is thick in the can, but it spreads easily because of its thixotropic quality.

M ost woodworkers do their finishing with one of two wipe-on/wipe-off finishes: oil/varnish blend or wiping varnish.

Oil/varnish blend is a thinned mixture of boiled linseed oil or tung oil with alkyd or polyurethane varnish. You can buy it commercially (often labeled "Danish oil") or you can make your own - for example, one part oil, one part varnish and one part mineral spirits.

Wiping varnish is alkyd or polyurethane varnish thinned a quarter to a halfwith mineral spirits to make the finish easy to wipe on and off the wood. You can buy it commercially (rarely labeled for what it is) or you can make your own by thinning any varnish or polyurethane.

Both finishes are easy to apply and produce near-perfect results. But they differ significantly in sheen and water resistance.

Oil/varnish blend produces a pleasing satin or "rubbed" sheen, but the finish is too thin to be water-resistant. This is because all coats have to be thoroughly wiped off or the finish dries tacky.

Wiping varnish can be left in thicker applications because it dries hard. So it can be built up enough to produce excellent

water resistance. But wiping varnish produces a gloss sheen many woodworkers find objectionable. (Of course, you could always rub the final coat with fine steel wool or other abrasive to lower the sheen, but doing this adds a complication most woodworkers would rather avoid.)

Gel varnish, which is also available as gel

polyurethane, can be thought of as a compromise. It produces an attractive satin sheen similar to an oil/varnish blend but with better water resistance, and it is almost as easy to apply. It also has a very low odor, which makes it especially user-friendly for home workshops.

If you've ever applied a gel stain, you're familiar with gel varnish. It's exactly the same, just without the pigment colorant.

Gel varnish has been around for decades, but it gets much less attention than the other two finishes and it is often difficult to find. It is sometimes labeled "natural" gel stain when the manufacturer intends it for thinning or reducing the color intensity of its colored gel stains. But it is the same as a gel varnish.

What is Gel Varnish?

Manufacturers change the consistency of liquid alkyd or polyurethane varnish to that of a gel by incorporating a thixotropic addi-

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Brands. Here are four brands of gel varnish. Notice that some are polyurethane varnish rather than alkyd varnish and some are packaged in squat cans that make it easier to get to the finish near the bottom with a cloth.

74 ■ Popular Woodworking December 2009

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