With the pigment from the Conestogo river collected and purified I began to test the effects of heating in earnest. Increasing the temperature by 100ºF each time, I tested the samples from 300ºF (150ºC) up to 1700ºF (925ºC). This was a whole day’s work, as the kiln needed constant attention and the samples were being changed every five minutes. I ended up with almost 50 batches of colour, which show a rather sudden change of colour at certain temperatures (there seems to be three distinct temperatures where the shift is quite sudden).
Making this, “map” of colours for Conestogo pigment was a lot of work, but it will be a very clear guide and it will be essential to have this as my work moves forward.