Talking to an old mason about lime mortar made me change my whole mix
I was working on a repair job for a 1920s house in Cincinnati last week, and the homeowner had his grandfather, a retired mason, stop by. The old guy watched me mixing my standard bagged mortar and just shook his head. He said, 'Son, that wall breathes. You're sealing it in plastic.' He explained that for old brick, you need a softer, more breathable lime-based mix so moisture can escape, or you'll spall the face right off. I argued at first, but he walked me through a simple test with a vinegar drop to check for lime. Sure enough, the original mortar fizzed. I switched my mix for that job, adding NHL 3.5 lime, and the color and texture match was perfect. It hit different because I've been doing it the 'modern' way for ten years without thinking. How do you guys handle mortar specs on historic repairs?