For this test, I used tiles of the same clay fired to cone 6.
The left tile was dunked into very creamy raw milk and air-dried three times, and the right tile was sponged down with the same milk and air dried three times.
They were then placed in the oven, and then heated to 550Â° F. I expected it to take a while, so I waited about 15-20 minutes before checking on them.
The left tile was a glossy BLACK. The right looked about like it does in the photo.
I decided to see if any of the carbonized milk could be scrubbed off with a scrubby pad and water, and what you see on the left is the results of that. The areas that scrubbed the barest were the areas where cream streaks stuck to the ceramic. I suspect the cream prevented the more sugar- and casein-heavy milk from adhering to the ceramic body, which kept it from carbonizing in the fine texture.