Ok. Noob question for you. I'm guessing that this a lost cause, but have to ask. I have small furnace that has developed a rather serious crack that goes all the through refractory in one area. Anyone have success with patching or is it typically a waste of time/effort? Can't add more than another .5 inches of material on the inner walls. Any more than that wouldn't leave adequate room around crucible. Refractory is an air bonded, plastic material from a company named Plibrico. About 2 inches thick. It's super dense and really tough (when cured correctly). The crack started more superficially when I first heat cured refractory too quickly. Other than this one serious defect, refractory is in great shape. If not for current zombie apocalypse, I'd be able to acquire more of same refractory. However, currently, I am restricted to whatever I can buy online.
If it's really bothering you just chisel out a small v and pack it with mortar but I wouldn't worry about it at all. It's now your built in stress reliever for the rest of the structure as it heats and cools and I'd bet the furnace will perform just as it always has, with or without patching the crack. Best, Kelly
It seems to be a rule that solid (as opposed to segmental) lids and hot faces will invariably crack. That certainly has been my experience and many others report the same. Usually the cracks are unimportant, at least initially. Successfully eliminating a crack with any treatment seems unlikely. Most people just accept them and ignore them. So far, all of my iron furnaces have eventually failed and all have been either solid refractory or wool/ Satanite constructions. Today I am casting my first segmental furnace lid from BluRam HS plastic refractory that I acquired for the first time. I will soon be starting a thread on this endeavor as I am unaware of anyone building a segmental (pre-cracked ) lid or hot face. Kinda busy today building segments and flasks. Mifco furnaces are segmental presumably to reduce cracking. Denis
@Al2O3, @Melterskelter. Appreciate the feedback! Made my day a bit happier. I'll give patching a go. At temps that I'll be running the furnace, wool wrapping refractory will get burned up pretty fast, since it's rated for up to 2400 F. Furnace was pretty simple given it was my first. Had 2 inches of refractory wrapped in kaowool. Then, foot or two of dirt/sand. Used fire brick for lid. Named it the ugly duckling. If you look at attached pic, you will see why . Pic is refractory only. Thanks again.
