White Nomad Posted June 17, 2020 Share Posted June 17, 2020 So I understand that in a solid fuel forge, the refractory material for the forge lining isn't as important as for a gas forge, however, I've made a mix to line my new side blast JABOD style forge and I'd like some of you guy's opinions and advise on the matter. The mix is 2 parts clay, 2 parts lime and 1 part wood ash. I'm thinking the clay and lime will form a solid and tough structure and the wood ash and lime will help to increase the temperature I can reach without starting the melt the lining. Would this work? Or should I add something else to the mix? Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2020 Share Posted June 17, 2020 2-3 parts sand to 1 part clay and JUST enough moisture you can ram it hard. If it starts melting scrape the melted part off. If you want to put lime in it sure why not? The sand can move in the dried mix allowing it to expand and contract easily while the space between particles allows moisture to steam off and escape. The DIRT in a JABOD isn't intended to be permanent or particularly long lived, it's just a box of dirt. It doesn't need to be hard, durable or anything other than hold a fire or a couple fire bricks up if you want a fancy JABOD. When you mix it up DO NOT make mud or it WILL shrink check as it dries, you know, crack like a dry mud puddle for the same reason. Yes? Don't over think it okay? It's just a box of dirt. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
White Nomad Posted June 17, 2020 Author Share Posted June 17, 2020 Yeah, I prefer to not work with sand in the mixture just because of it's (relatively) low melting point. The lime allegedly has a melting point of around 2800 celsius so I figured that It would hold the heat well. I've worked with clay before and have sort of learn the golden ration of water to mass for mixing the clay. Thanks for your help. I'll keep it in mind. - White Nomad Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2020 Share Posted June 17, 2020 The dirt in a JABOD isn't there to hold heat, it's there to protect the wood box and contain/shape the fire. Not all sand is silica, lime sand would be perfect. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
pnut Posted June 17, 2020 Share Posted June 17, 2020 The lining material will vitrify. It took a sledgehammer to break my last jabod apart. You could tap the fire trench and it tinked like glass. I was astonished at how hard the lining was. I even tried adding water to make it easier to break up but essentially it was fired clay so it didn't help until the layer that was fired hard was removed. Don't over think it. As Frosty said the clay is only to hold the fire and keep the box from burning. Good luck. Pnut Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 17, 2020 Share Posted June 17, 2020 Lime might melt at a high temp but what temp does it calcine at? (1652 degF 900 degC) So below forge welding temps by quite a bit. I'd rather work with vitrified clay/silica than quicklime! Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2020 Share Posted June 17, 2020 OH . . . , I didn't think of that Thomas! I think I'd much prefer to deal with vitrified sand than quick lime wafting on the breeze. Talk about badness, think about Draino eye wash and hand cream. Gimminy chemical burns! NO LIME in the mix to clay your forge. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
White Nomad Posted June 17, 2020 Author Share Posted June 17, 2020 (edited) Alright, I'll switch the lime out for sand Edited June 18, 2020 by Mod30 Remove excessife quote. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2020 Share Posted June 17, 2020 I did a little looking at your local geology and you might find a sand with a higher melting temperature than silica. Phyllite or shist is friable and might produce sand in quantity close by, maybe stream or river bars. Basalt is another option though less friable. Are there any: black, gray or sparkly sand beaches close by? Locally we have a river sand one of the club members collects and uses to make resin bonded molds. He casts bronze and it's hot enough to fuze silica sand and buying suitable sand is prohibitive. I believe it is a pegmatite sand but I'm not sure. I didn't see any pegmatites near Brisbane but it was a pretty shallow article. You have a rich geology if mostly sedimetamorphic. Finally, crushed pottery or fire brick "grog" should work a treat. As a last ditch, option a casting supply should carry sand with higher melting temps than silica. I don't know if vitrified silica will be enough of a problem to make you want to look into alternatives but if it is, these are what I can think of that should be available to you. I think. You have NO idea how badly I feel for not shouting a warning immediately about putting lime in a forge fire, that could've caused permanent damage. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
White Nomad Posted June 18, 2020 Author Share Posted June 18, 2020 I have some zeolite and bentonite as well, would that be any good? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 18, 2020 Share Posted June 18, 2020 However all of this is pretty much overkill when people have been using clay and wood ash forges for centuries with decent results. You don't need a formula 1 race car to learn to drive in! Quote Link to comment Share on other sites More sharing options...
Irondragon Forge ClayWorks Posted June 18, 2020 Share Posted June 18, 2020 I know the bentonite will work, don't have any experience with zeolite. Try mixing a little in with the bentonite and let us know how it does. We love guinea pigs don't ya know. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 18, 2020 Share Posted June 18, 2020 Just dirt is fine. If it won't hold together maybe a LITTLE bentonite like a couple three tablespoons will make it plenty sticky. If the zeolite is sand it might work but there are so many different variations in the mineral group I don't have a clue if what you have is better than silica or not. All the sand is for is to keep the dirt from becoming a single impermeable mass and prevent it shrink checking or steam spalling. You can mix lawn cuttings or crunched up leaves for the same effect. Think of the JABOD as a trench forge scratched in the ground but at a more comfortable working height. That is ALL it is. Plain dirt ashes if it needs some binder and tamp it in just damp enough it clumps in a hard squeezed fist. Everybody is getting into different ideas, I sure did but we're forgetting the beauty of a JABOD. It's Just A Box Of Dirt. Just KISS it, you have the rest of the time you continue blacksmithing to look for what works best for you. Just relax, build a fire and have some fun. Okay? Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
White Nomad Posted June 18, 2020 Author Share Posted June 18, 2020 Will do, and I'll experiment with different combinations of clays and ash mixtures and let you guys know how it goes, probably in a different thread though Quote Link to comment Share on other sites More sharing options...
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