Don’t get me wrong, I love to talk about masonry but was a little concerned about the colourful
vocabulary I’ve picked up over the years. After decades spent on building sites and a teaching stint at a Mississippi prison, speaking in formal settings can feel unnatural. Nevertheless, it went well. No one fell asleep and everyone was upbeat and participated beyond my expectations.
We began with a brief history of lime mortar and its manufacture in days gone by. Matt (Wolf) went into great detail about the chemical makeup of lime, the lime cycle, and Portland cement production. More particularly, we discussed the properties of lime mortars and how they behave more sympathetically with old buildings, while Portland cement is incompatible as a restoration material for buildings where the original joints contain soft, breathable lime mortar. We also discussed older Portland cement and how it differs from modern Portland. After the talk, the real fun began - hands on masonry. The first job on the list was making a proper “hot mix “ with real lumps of quicklime, slaked and mixed with the proper proportions of sharp sand (It was probably the first time this has been done in the Milwaukee area since the 1940’s). The slaking quicklime produced a lot of heat, which not only dried out the sand in about 40 minutes, but was much appreciated in the cold morning as we warmed our hands above the mix. We then mixed up some pure lime putty for laying some gauged brickwork (this is laid with tight mortar joints - sometimes called butter joints - that are around an eighth of an inch thick). We used salvaged iron spot bricks and built with great enthusiasm - a couple of students even carried on laying brick long after the class was finished.
