Tried a new lime mix on a chimney rebuild and the difference was huge

I was repointing an old chimney in Cincinnati and swapped my usual type N for a type O mix. The type O was way softer and more forgiving on the hundred-year-old bricks, didn't force any cracks. Anyone else use a different mortar spec for historic work?

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3 Comments

bennett.noah6mo ago

Interesting, I've actually had type O fail early on softer bricks. What was your mix ratio?

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thomas3466mo ago

It's funny how the "right" mix can still go wrong depending on the material. I see that a lot with other stuff too, like how a perfect paint won't stick to a certain wall.

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xena_fox396mo ago

Yeah, that's the worst. Had a batch of lime mortar fail on some old, really porous stone because it dried too fast. Ended up having to mist it with water for like three days straight to get it to cure properly. The mix was right, but the material just sucked all the moisture out.

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