Use of Old Fire Brick

[majikmatt]

The family passed along some Fire Brick as an old outdoor oven of my wife's Grandmother was demo'ed. Is there something I should be looking for to verify quality? Originally I'd planned on using it for my oven floor but after reading post after post I realize you want clean sharp level edges. Obviously this brick has been handled multiple times. There are gouges and edges that are chipped. I cleaned a lot of the old mortar off to use them on my project.

I'm wondering if (since I'm going to need a lot more brick) I can incorporate the really good bricks in the floor then use the rest of them elsewhere in the build.
Any advice is appreciated. Some really ingenious folks on this forum.

[SableSprings]

Welcome Majikmatt! We generally recommend new firebricks for the cooking floor (as you suspected) for consistency and safety. Safety, because you don't know what was burned/used in the previous oven and although contamination from the dome would rarely be an issue, it might be from the direct contact of food to the floor. I used old firebricks from a prune drying oven and, like yours, they had a lot of gouges, chips, and broken corners. By simply cutting them in half, I always got a "clean face" that I installed facing into the oven. The poor edges & gouges are hidden from view and nobody sees the "original" flaws.

I applaud your wanting to incorporate those bricks from your wife's Grandmother...it's good heritage karma! I suspect that because it was used in a previous outdoor oven, they have proven their quality for use in your new oven.

[majikmatt]

Thank you for the intel. Your Dragon Fly build is amazing!!

[majikmatt]

New information:

I’ve happened upon a 1/2 pallet of Med Duty firebrick. 9-1/2 straights. It has seen better days, relatively brittle & some small fissures from what I can tell. Planning on cutting into a few of them today to get a better look. Am I setting myself up for failure by trying to use these as my dome? I’ve sourced them from a local refractory supply store so as for quality their legitimate firebrick.

Thanks!

Also, the further we get into fall am I asking for trouble by starting my WFO? If I’m halfway through and we hit a cold snap (Colorado) would I be contending with moisture in the brick & mortar freezing/cracking?

[SableSprings]

I had a bunch of old used fire bricks from a prune dryer. Lots of damaged corners and edges (and discoloration). I cut them in half and put the cut side facing in...worked great for the build. There are some small spots where my refractory mortar "fills in a bit" but my oven's going strong after 11 years of pretty consistent work. I suspect the bricks you found will be mostly usable, especially if you halve a couple and find you can get a good face on them. I did use only new bricks on the cooking floor.