Going old school

Like many people today, I imagine, I was introduced to lime, or quicklime, by Tom Sawyer. You know, the part where Tom has to whitewash the fence and get's the neighbor kids to do it while he "supervises". I really hadn't given it much thought since.

My house is old. It was built in 1920. The house, itself, is made from stucco and the property is lined with a wall made from old adobe bricks. I needed to seal a bunch of stucco cracks so I hired a painter to paint the house (not the wall) with some high-powered masonry paint. I wanted the sealing properties but the painter was very interested, as you might imagine, in making sure the house looked as good as it could. It looked pretty good. Then there was the wall. My painter, let's call him Maurilio, kept eyeing the wall. He knew I couldn't afford to get the wall painted by him and he knew me well enough to know I probably didn't want to paint it myself, at least not with paint. One day we were standing in the shade by the wall and Maurilio told me that back in Mexico, sometimes people would use lime to paint masonry white. And it was as he said. Actually the process dates back to at least the Roman Empire.

I bought a sack of lime (around $8 for 50 lbs). I experimented with the consistency. You can make it thick (that's called plaster) or thin (that's called whitewash). Thick does some structural repair but thin is way easier to apply. When I got the consistency to the compromise I wanted I slopped it on. It was somewhat disconcerting at first as it was mostly a grey slurry until it dried. Then, through the miracle of chemistry, Calcium Hydroxide (Ca(OH)₂) and water becomes, with the absorption of CO₂ from the air, bright white limestone (CaCO₃). I don't know how often this needs to be redone but it's kind of miraculous.