Well spring will be upon us soon and I want to build a permanent forge in my garage/shop. I love coal and will build a side draft type forge but I want to use natural stone not brick (at least not all brick). Has anyone had dealings with this ? I have heard if I use the wrong stone they can get to hot and crack and break.
I would love to hear from anyone who has done this as I want to end up with a lovely forge as well as a functional one as well.
Thank you
Firegnome
Jim Heckman
Hampden, Maine

Actually some stones explode and can cause blindness or death when heated. However most ultramafic igneous and metamorphics are generally more polite and the bad ones merely crack. (as a geologist I used to get the duty of fire testing stones for a LH kitchen where we cooked by heating stones and dropping them in water.)

However in a masonry forge the stones are more of a frame and the actual fire area should be made from firebricks or fire clay.

May I suggest you locate a local historical forge and see how they did it and how well it lasted with local materials?

Out here I'd go with basalt...

Thomas,

There believe that there are slate mines about 1 1/2 hour northwest (Monson) of Jim. Would dry-stacking slate be a safe option?

Do a search on Dimitri Gerakaris and Anvil's Ring Vol. 7 #1 from March 1979. He describes in detail the process of building a natural stone forge (I think he used granite but I'm going on memory). He is also in North Canaan, New Hampshire so might be someone you could visit.

Jim- If you ever get over to Vermont check out the historic replica forge at the Lake Champlain Maritime Museum. They have a very nice stone forge, works very well. We (Green Mtn. BA) have hammer-ins there sometimes. I have heard that Dimitri Gerakeris isn't too keen on drop-in visitors, might want to contact him first.

You can make your forge out of any stones that take your fancy as long as you line the firepot with some clay or refractory.

Cheers

My experience with slate would indicate that "it depends" Had slates that were very fire safe and other that crumbled when heated---we used to cook chestnuts on a roofing slate in our fire place...

But as mentioned if the stone is away from the hot zone not much of a problem...

Seen large permanent forges here in Aus that were built out of timber and roofing iron, you just need to make them large enough so as the heat does'nt get to the framework. Most of these timber forges were filled with dirt and clay with a side blast tuyere. Just make sure the rocks don't get hot and it will be no worries.

cheers
Phil

I don't know of any stone that would work being in direct contact with the fire, they will crack, explode or basicaly melt from the heat.
Build it out of anything you like but make the fire pot out of firebrick or refractory and you won't have any trouble with the stone.

welder19

Welder, I have had several fireplaces and fire pits out of stone. Pull them out of the creek invites
disaster. If dried they are fine. I lived in the oldest inn in Conn for a yr no problems with the stone
fireplace.
Ken

The early american iron furnaces were lined with stone and they withstood rather intense heat for long periods; *BUT* they chose their stones very carefully for the lining.

Most fireplaces don't have forced air and therefore the fires are not as hot as a forge fire can get. I have seen granite pop and crumble under the heat of an acetylene torch.

Most granites will fracture at 1500 degrees. Play it safe use fire bricks or a castable refractory for the fire then use whatever stones you like to build the body of the forge.