SECRETS OF PAINT AND STAIN CHEMISTRY

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Some clues: Labels reveal the solvent base by telling what to use for a thinner or for cleanup. Water is the safest solvent, but may indicate that the stain contains alkyds or esters; look for hazard warnings and follow them. Once on and dry, the color is harmless. Denatured alcohol is the least harmful nonwater solvent. Directions to use an alcohol thinner indicates a shellac-type finish or a stain for which the solvent evaporates completely, leaving only color that can be covered with any finish. Don't use shellac to cover any alcohol-based stain or filler that leaves a film on the work, or one will dissolve the other. Mineral spirits indicate a varnish base for stain or filler; look carefully for directions for applying following coats.

Also, look (hard) for VOC (volatile organic compounds) ratings—now required on labels. These are benzene, naptha, and other volatiles that can harm air quality. These are slowly being regulated out of consumer products. Fgures are given in pounds of VOC per gallon, and since the specific ingredients are not identified, are meaningless in themselves. But you can compare and choose the product with the lowest VOC number. Also, the less VO's, the more solids in the product. Solids are what you pay for—what stays on your work; the volatiles just evaporate away.

There are all manners of combinations to make finishing a one-step process. Some are really good. Choose brands that have worked for you in the past, and follow label instructions.

MILK PAINT

The lovely muted colors of much Colonial furniture come from paint that was home-mixed using primitive dyes and fillers with the protein in skim milk or in curd as a binder. Today, you can buy dry milk paint ready to stir into water, or make your own from powdered skim milk and painters lime, plus any dry or water-soluble liquid pigment you fancy. Experiment to find the mix that works best starting with 50:50 (by weight) of dry milk and lime with enough water to make a thick latex-like paint.

Add room-temperature water to get a milk paint that is thick like modem latex wall paint. Added binder quality can be had from mixing in flour paste or arrowroot. Mold-preventative fungicide additives are highly toxic, but I've heard that adding enough salt so you can taste it will keep molds from growing on milk protein, wheat paste, and other organic paint components in humid weather.

You'll have to experiment with the amount of pigment to use; mix trial batches with water, apply samples, and let them dry to get your colors right. Just be sure you mix and tint the entire finished lot of any homemade paint you'll need in one batch or you'll have variations in quality, tone, and tint. Strain the paint through cheesecloth before applying.

One warning: once on and well dried, milk paint can't be stripped off with modern petrosolvents. Only good old-fashioned caustic soda (lye) will do the job, and the paint takes its own sweet time letting go. I find that satisfying in a perverse kind of way, don't you?

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