Warning: I mixed a small batch of mortar with a different brand of lime on a chimney repair in Denver

I was finishing a repoint job and ran out of my usual type S lime, so I grabbed a bag of a different brand from the supplier. The mix felt fine going on, but after two days the joints were still soft and crumbly, not setting right at all. I learned that even with the same spec, the particle size or purity between brands can really mess with the cure. Has anyone else had a mortar fail because of switching lime mid-job?

3 comments

3 Comments

the_jana1mo ago

Yeah that's a rough lesson to learn the hard way. I've had similar issues when the bag wasn't stored right and the lime got a little damp.

matthew3941mo ago

Check if your storage container itself is sweating. Sometimes the condensation forms inside the bag or tub, not from the lime. Happened with my airtight container in a warm garage.

milesk271mo ago

Honestly that's such a good point about the container itself. Tbh I lost a whole bag of mortar mix that way once, swore it was sealed tight. Turns out the plastic tub was just sitting in a sunny spot and sweating like crazy on the inside. Ngl it makes you check everything twice now, even the bags inside the bins. A real pain to deal with for sure.

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