Firing temps and brickmaking

The finished color and hardness of a clay brick has alot to do with the highest temp achieved and length of time held there before cool down. There doesn't seem to be as much effect on outcome if the ramp up time to peak temperatre is varied shorter or longer. Obviously the type of clay will have a profound influence on the finished product as well. But here I will focus on firing temp of a single type of clay.

Below are tiles and bricks of the exact same source of clay, prepaired the same way before firing.

They are identical except for the one brick on the lower left. The three of the same color were fired to 1900 deg F over an 8 hr period in my electric kiln. The darker brick made at the same time as the others, was fired to 2000 deg F over 9.5 hrs in the same kiln. All settings on the kiln were identical.

The surface of the darker brick is closer to that of a paver or clinker. It has a reflective quality to it that the others do not. All the bricks and tiles are fired fully and have a strong 'ring' when tapped together. The darker brick has a higher ptched ring to it.

If I were to ever try to make pavers or outdoor tile, they would be fired much like the darker brick. I believe the water proof qualities should be higher.

Notice the small paw prints on the one tile. My kittens were having fun after I made up the tiles.