SECRETS OF PAINT AND STAIN CHEMISTRY

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In the old days, the cheapest finish around was a white paint homemade from lime and water. It was called whitewash—the stuff that Tom Sawyer used to get this famous fence painted. Rain washed it off easily, so it needed to be reapplied every year or two.

Whitewash was used to brighten up and sanitize interiors—more in barns, workshops, and factories than inside homes (where it would flake and get all over everything). Augmented sometimes with an adhesive binder such as wheat paste, it was just sloshed on, one coat over another, year after year, with a wide, thick paperhanger-type glue brush or a mop.

The walls and ceiling of the milking parlor in my old barn were whitewashed, but have not had a fresh coat in decades. The big flakes that slough off the bottom of the loft floorboards and old half round log ceiling beams are a good quarter-inch thick from all the built-up layers.

PAINT STRIPPERS

Water is the solvent and brush cleaner in oldtime, pretech. whitewash, and most modem, hitech house paints. But, in the heyday of "interim tech" that brought us lead paint, chemists were refining evermore sophisticated mineral solvents from coal, tar and petroleum, and using them to make finishing products as well as brush cleaners and paint strippers needed to dissolve the products. In traditional paint-biz secrecy, ingredients in all these products were concealed from consumers, and many were (and are) hideously hazardous to both people and the environment.

Government regulators now require that contents of strippers be revealed on the container—but how many consumers know the difference between methylene chloride (fumes are virulently toxic) and N-methyl-pyrrolidone di-basic ester (sounds much more toxic, but is reasonably safe to use due to slow evaporation)?

Only one common stripper lacks chemicals and volatiles that can be harmful to you and damage air quality. This safest and most effective universal paint stripper is also the oldest: a solution of common lye and water. Lye, or caustic soda, is the strongly alkaline compound used to make soap from animal fats. It consists of sodium hydroxide—Drano drain cleaner you can buy in hardware stores and the grocery, or Potash (potassium carbonate) that you can make yourself by steeping wood ashes, draining off the water, and letting it evaporate outdoors (but up high and screened so it doesn't attract thirsty mice to an unpleasant demise).

Nothing but a saturated solution of common lye and water is what most commercial stripping tanks contain (ever wonder why there is no chemical odor in stripping sheds?). Lye takes more time to perform than petro-solvent-based counterparts, and it requires constant monitoring. Lye will dissolve old animal protein-based hide-or-hoof furniture glues, and if wood is left in the caustic brew too long, the grain will raise and the surface can be ruined. It is especially to be avoided in refinishing veneers and inlays.

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