5/17/10

Brick with Black Holes - Pop Quiz

How is it these bricks have black holes?

Check out the original mortar with its flecks of quartz and feldspar. It's almost 100 years old and remains perfect.

2 comments:

ty.ro said...

Sometimes certain minerals were found in specific clay bodies. During firing these minerals burned out (causing some interesting glazing techniques; in this case black spots).

Check out natural glazing techniques for clay, its really fascinating. A lot of it has to do with salts/minerals in the clay. Even certain glazing techniques are done by throwing a shovel full of salt into a hot kiln, having beautiful results.

Christian said...

Hi ty.ro!
Sorry for the late response, you wouldn't believe the series of distractions.
You're the winner of course.

I believe flecks of iron ore were used in the brick in this photo.