Fire Brick or No?

[Cloudfeather]

So, I salvaged these bricks a number of years ago along the river near me where a factory "Niles Fire Brick" used to be. They made bricks for blast furnaces and whatnot.

Was planning on using these for the floor of my oven build and decided to do a test fire. They're all cracking and I'm not sure if they're simply not fore brick or if they're full of moisture and need slow heated to get the water out of them. I've never seen "regular" bricks like this, so I'm hoping tor them being water logged and I can go salvage more.

I really like the idea of a piece of town history going into my build. Thanks.

[david s]

If you salvaged them they could possibly be from a store of rejects, hence left behind. Another possibility which is more likely is that the bricks contained a high proportion of moisture. All new kilns and ovens require a very slow and controlled schedule of moisture purging.