BEFORE. The Coastal Heritage Society of Savannah Georgia whitewashed the masonry wall around the Roundhouse Railroad Museum using St. Astier lime paint, and “all volunteer” labor, per Tom Sawyer.

For decades, now, paint companies have been touting “water based” latex paints, that supposedly outperform oil based paints in exterior applications, but don’t. That’s what advertising is for, getting you to buy the paint, but no amount of advertising can make a plastic film last longer on the wall. There is one traditional, water based “paint” that is getting some reappraisal, however and that is “whitewash”, or lime paint. Whitewash is breathable and quite durable over some surfaces, especially masonry. In some sense it is more of a stain, than a true paint, forming a masonry bond with a masonry substrate. The lime based film cures by reacting with carbon dioxide in the atmosphere to form calcite, a reaction known as carbonation. Generally applied to exteriors, it has traditionally been used in interior applications as well, especially in rural areas. Anybody who has spent much time in a period commercial dairy barn will have noted the full application of this material over interior walls and ceilings, wood and masonry alike. Being breathable, it tends not to peel in exterior applications, but rather to wear, so application of additional coats is straightforward and cheap. Or free, if you apply the Tom Sawyer whitewash application labor management technique. St. Astier Lime Paint is available in “natural” (aka “whitewash”) and in over a dozen Mediterranean tints, from Limeworks, the Pennsylvania distributor of traditional lime based masonry solutions.

AFTER.