Friday 27 April 2012

cement free


I don't remember if I said so, but when the big snow stopped us in our tracks, Richie and I couldn't continue working in the cantina because the mortar would freeze. We decided to move operations up to the middle floor and work on the unfinished back bedroom. I was happy to find his formula for plaster mixes was faithful to the original plasters using very old fashioned materials. This required more time to prepare and apply and along with his high standard of perfection Alex and I began to wonder if a few short cuts wouldn't be more economical. Once we got rolling with tools and techniques, the process began to speed up to the point today where we are racing through the walls downstairs.

We are using lime-based plaster which we mix using plain old powdered calcium hydroxide (white hydrated lime), sand and water. The calcium hydroxide, water and air (CO2) turn into calcium carbonate (limestone). Unlike portland cement based mortars and gypsum based plasters, the old lime processes are environmentally passive and are also much more compatible with crumbly old buildings like ours.

As if my philosophy of slow progress wasn't slow enough, now we are incorporating slower setting, older-fashioned plaster formulas.