How to tell if a brick is ok for the dome / or not ?

[antique dave]

Hey guys / gals ,
I have just dug the hole and getting ready to box it up for the foundations of my first pizza oven build .
For the base frame work I'm using hollow blocks (known as breeze blocks in NZ) then intend to use old bricks as a outer layer to match our 75 year old house .
I've already got all the bricks but I'm not sure which ones came from a fire place .
Is their any way of telling if a old brick is a fire brick that could be used in the dome or am I better just going out and buying some new ones ?

[Gulf]

Dave,

Welcome to the forum. To get right to the point, it is best to buy new fire brick for the oven floor and dome. But, the price of fire brick in the Southern hemishere is outrageously high. That said, fire brick will usually be more dense (heavier) than solid clay pavers. They tend to be lighter in color. More toward a yellow or light tan (bisque). They may be a different size than regular brick in the stack. Since only the firebox is lined with them, there will usually be very few, (if any) fire brick mixed in with a stack of residentially salvaged brick. Some pics and a rough count of the bricks that you have on hand would be very helpful, There may be some interesting reading hear in a Google search of the forum's discussions about, Fire Brick in New Zealand.

I hope this helps.