Allomancer Jak Posted June 10, 2017 Share Posted June 10, 2017 I'm making a coffee can forge to get my feet wet, and I'm planning on using perlite for a refractory lining. I've been seeing some people say to use sodium silicate to bond it, and others say to use watered down furnace cement. Which would be better, and how long would each take to cure? My plan is to have a second, inner lining either way. Any hard facts would be welcome! Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 10, 2017 Share Posted June 10, 2017 Perlite is going to melt at typical forge temperatures, and so will sodium silicate; this combination is only used as secondary insulation. A mixture of Perlite and furnace cement will last longer, but will also fail. Ceramic wool blanket is normally what is used in coffee-can forges. The blanket is also rigidized with fumed silica and given a tough sealing coat. Quote Link to comment Share on other sites More sharing options...
Allomancer Jak Posted June 11, 2017 Author Share Posted June 11, 2017 Thanks, that's good to know. I have another idea. Let me know what you think. I could put a firebrick in the can and pack the perlite and furnace cement mixture around it and insert a pipe in the side, then carve out the firebrick and make a one-brick forge out of it all. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 11, 2017 Share Posted June 11, 2017 If you use2600 F firebrick, which is somewhat insulating, that would probably work just okay. If you are talking about a typical clay based firebrick, with almost zero insulating value it will only work for short periods. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 12, 2017 Share Posted June 12, 2017 BTW, what are you planing to use for a burner? If you are about to say that it will be an air-propane torch, I suggest you read the thread called Burners 101, because the only way that torch can be stopped from overheating, is to aim it at the opening (burner port) from outside; it will then do a lousy job of heating your forge. Quote Link to comment Share on other sites More sharing options...
Allomancer Jak Posted June 12, 2017 Author Share Posted June 12, 2017 17 hours ago, Mikey98118 said: BTW, what are you planing to use for a burner? If you are about to say that it will be an air-propane torch, I suggest you read the thread called Burners 101, because the only way that torch can be stopped from overheating, is to aim it at the opening (burner port) from outside; it will then do a lousy job of heating your forge. Thanks for the tip! Very good to know. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 13, 2017 Share Posted June 13, 2017 Jak: The tip Mike was trying to give you is to read Burners 101. . . To start. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 13, 2017 Share Posted June 13, 2017 When and why NOT to choose a coffee-can forge There seems to be some confused ideas about coffee-can forges being a cheap way to get into heating up metal. What they are is an economical way to forge small parts after the forge is built; the economy comes in minor fuel use. They are also highly portable and compact tools, for those with limited space. The only savings encountered in their construction will be in the economies of scale. You can find ceramic wool blanket offered in squares that are large enough to work in a C-C forge, so you spend less money for it. But, those offers are also a rip-off, so far as how much you end up paying per square foot. Mixtures of Perlite and water glass are going to melt in short order. Perlite and furnace cement are going to break down more slowly, but they still cannot hold up to forge temperatures. You would need Perlite and castable refractory to do the job, and then you have just lost enough money to by that square of ceramic wool blanket. The infamous plaster and sand 'refractory formula' is such a major heat sink that you will end up throwing you forge in the garbage before the so called refractory has a chance to disintegrate! The second cheap and easy idea about C-C forges is that you can run them with propane canister-mount torches; yes and no. There are only a few very high priced propane torches that have stainless steel flame nozzles, and their nozzles are so thin that they will quickly oxidize away inside of a forge. Most of these torches have brass nozzles that will melt inside of a forge. So, the torch cannot be placed in a sealed burner port. Instead, it can only be placed in an oversized hole, if it is weak enough, or aimed toward the hole from outside of it, if it is one of the hotter models. Anyway you go, either the torch is destroyed of the forge is under powered. So, you need a real burner. But, if you're going to the trouble to build a burner, you want it placed in a forge that is worth it, right? Now you have another problem, because a 3/8" burner is the largest size you can use in a C-C forge, and the only one you can build is a Mikey burner; it can be found in the Burners 101 thread, but by the time you've constructed it, you won't want to waste it in a forge you just built to save money! There are plenty of burners you can build in the 1/2" size, if you're willing to put them in the typical mini-forge (built from a non reusable Freon of helium cylinder). Coffee-can forges have their place, but trying to use them as a cheap and easy way to heat steel, is crazy; that's what charcoal if for. Quote Link to comment Share on other sites More sharing options...
Allomancer Jak Posted June 13, 2017 Author Share Posted June 13, 2017 Ok, I appreciate the advice, and I have started reading through Burners 101. As you mentioned, space is an issue, and that's one of the reasons the C-C forge appealed to me. My primary use for it would be heat treating, not forging. I'm not sure if that makes a difference as to your advice though. Right now I'm just trying to find a local supplier of refractory materials. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 16, 2017 Share Posted June 16, 2017 Yes, because lower temperatures can be attained by aiming the torches I don't recommend at a hole; on the other hand, such a forge can be run with a 1/2" "T" burner; at present this is the easiest burner to construct, and you can also find lots of help in constructing on right on this group. Now, aren't you glad you asked that question Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.