Waterlogged firebrick?

[Tenebr0s]

I'm up in Vermont for a for weeks at my parents' place, and thought I would build a small side-draft charcoal forge.  We've got a bunch of firebrick that have been sitting out in a field, and they are very wet and moldy.  Do any of you guys know whether they're ok to use?

 

 

[Steve Sells]

after you dry them out,  it may be fine

[Chinobi]

Used wet there is great potential for fracture or explosion.
Dry them out slowly and measure the amount of weight lost over time (use a reasonably accurate scale) until the change in weight between measures is zero 3-4 times in a row. Then you have a reasonable assumption of dryness.

Whether or not storage in the waterlogged state or the presence of mold has affected the properties of the brick, I cannot say, sorry =

Edit: you say Vermont. Are you in an area/are they stored in an area of the property that is subject to freeze/thaw cycles? Freezing a brick and the associated expansion of water within the brick can break and crack it from the inside out. (it can destroy porous rock, concrete, and asphalt in the same conditions, seems plausible that a brittle, porous firebrick would not fare well in that situation)

[Tenebr0s]

Thanks for the replies!  They have definitely been subject to at least three or four freeze/thaw cycles.  I'm actually surprised they are still in one piece.  Maybe it's just safer to pick up a few new ones at Ace Hardware.  I recall they're not too expensive there, and I don't need that many since this is going to be a small forge.

[ThorsHammer82]

Its my understanding that fire bricks are more dense than regular bricks. The wet area might not be as deep as you think. You might try cutting 1 to see how wet the inside is. If they haven't fallen appart yet from the freeze thaw cycle you're probably safe from that. but you do want to dry them out before you build anything out of them. stack them up a safe distance from a fire. Close enough to get warm, but not to close that they get hot. The warmth will get the moisture out without causing the bricks to explode from rapid expansion of gasses.

[ianinsa]

Many places you can get salt real cheap if you pack them in salt and they put the damp salt in the oven to dry out before repacking you should be able to dry out with out "harming the bricks".

 

Watch out if you use heat to dry them out steam expantion can have volatile results(a serious OOOOh Fudge{or somesuch } moment it takes surprisingly little heat to get dramatic results.

 

Ian

[K. Bryan Morgan]

I've seen people use brick pile side draft forges for quite a while.  Put the bricks under cover for a few days.  Sunny porch ect. and then get busy.  Bricks are fired between 1800 and 2300 deg f.  So I don't think you will get them near that.

[Steve Sells]

another way to dry is pack in rice (uncooked of course) . works for cell phones and computers

[Frosty]

Fire brick is fire brick because of a couple significant differences. They are a high iron content clay, the mix has a significant % of sand, usually silica sand. The iron clay just takes more heat but the important ingredient is the sand, it causes fire brick to be more porous allowing moisture to escape safely and gives the brick some flex so it doesn't crack from thermal shock. In this case the thermal shock needs to be reasonably graduall, just taking a cold fire brick and putting it in the forge will break it up and possibly cause a steam explosion.

 

Dry it for a couple days, warmer than ambient a little air movement is really good a light bulb is perfect. Then stack them openly around a small fire, once the brick is coffee cup hot to the touch, let it soak for a couple hours and increase the fire size after a few hours just allow the fire to grow to the brick and they're good to go. You'll find out if any will pop or heat check.

 

Just remember, time is money, you can always get more money but time is a one way ride. Drying those bricks is going to be a couple days so it's up to you, buying a few may be more economical. However, whatever you do, get the rest under cover so they'll recover from exposure and you can use them at another time.

 

An old acquaintance gave me a bunch of large fire brick from a power house furnace rebuild some years ago and they've been laying outside for a number of years now. There's been no freeze thaw damage and as long as I take it slow no steam spalling. Those are not normal fire brick though, they're longer and wider but about the same thickness as normal commercial brick. So, I won't offer them as an example of how regular fire brick will behave. This last is just an anecdotal statement of limited relevance.

 

 

Frosty The Lucky!

[Tenebr0s]

Thanks all for the replies.  I dried the bricks around a fire for four hours or so, and they are fine now.  Set up the forge and had it firing all day today without any problems.  These are hard firebricks, not the soft insulating kind, so I think they absorbed a lot less water.