Progress went well on the Saturday of the Frontenac Arch workshop. The sandstone turned out to be fairly easy to shape. The guys working on the project picked up the principles fairly quickly and were making some good structural decisions. The hearting is a bit of a problem. The sandstone we are using doesn't seem to be nestling or fitting into the spaces as nicely as we would like. It is abrasive and a bit brittle. It's turning out to be not that handy as for wedging either. The smaller pieces have much less of an ability to shim the bigger building stones, the way limestone or granite chips would do, and so to avoid the wedges getting crushed with the weight and pressure of the bigger stones we think that we should to introduce granite instead for the important pressure points. Apparently limestone pieces would not work in combination with the sandstone, as acid solutions that wash carbonates from the limestone can chemically affect the durability of sandstone.
I have not read anything that says granite and sandstone should not be used in combination, but if anyone has heard this isn't a good idea, please let us know. But for this project at least it's off to find some nice granite rocks to break up and make better wedges to work into the arch structure today. It's not like there isn't a lot of granite to choose from in the this granite epicentre of the Ontario, here at the Frontenac Arch Biosphere.