coating wool with mizzou

[maddog]

I'm building a small forge I was thinking of lining the kaowool chamber with 1/2" of mizzou. I find Satanite too crumbly. My plan is to lay the wool out flat and butter it with mizzou about 1/2" thick then roll it up around a cardboard tube. I will moisten the wool and keep the whole thing moist until it sets. Any thoughts?

[Dodge]

IMHO, I think you have a good plan of attack; I was thinking of a similar method on my "next" forge That being said, in my experience, I have found that the coating on the ceramic wool serves to protect the wool from damage and little more other than being able to withstand the heat. The wool is what is doing the insulating and the coating if any thicker than needed is just becoming a heat sink. Yes, it will hold the heat longer than the wool by it self, but it will take a bit longer to get to heat than the wool by itself. Forges have been made with just refractory in the way of ramables and castables with varying degrees of efficiency. In general, forges lined with wool and properly coated, heat up nice and fast but are more affected whe you put cold steel in. A forge lined with solid refractory will take longer to heat, but are less affected by inserting cold steel because they hold the heat better. I used AP Green Greenpatch 421 ( http://www.wardburne...CH-421_data.pdf ) on my current forge. Applied with rubber gloves at thickness of about 1/4", I feel both the coating and the wool are doing their job at there best conditions. The Green patch is hard as a rock but not so thick as to be a factor on heat up time (Which was my main concern. The faster you heat the forge, the less gas you use in the long run...I think ) My only complaint with the gp421 is that its a high alumina based product so flux likes to eat it. I will replace the floor with kiln shelf when I have to reline. Hope this helps

[eric sprado]

Maddog: Please let us know how that works.Keeping R-factor up and controlling wool dust is always a trade off that we like to improve on!!!I'm going to be building another small forge to save fuel on small projects...

[maddog]

eric: I will post results once I know whether it holds together. This is to be a very small forge with a 4"x6" chamber for economy and quick heat up. I want a forge that I can run for just an hour or so without having to invest a lot of propane in bringing it up to temp.

Dodge: My thinking is much like yours. The refractory has little insulation value. It's purpose is to provide a durable liner. The wool is there to hold in the heat. I've not been satisfied using kaowool with just a thin skim of some coating. I always have cracks develop and then the combustion gas gets into the wool. I run my forges hot and when the wool is exposed to combustion gases at that temp, it dies quickly. Plus it's very vulnerable to being damaged as the work goes in and out.

My concern is whether mizzou will work when used in a such a thin section and without being rammed. I will just have to try. If it doesnt hold up I will make a form and cast a tube about 5/8" thick.

Mizzou, Greenpatch & Satanite are all about 60% alumina and 40% silicon dioxide. Pretty much any refractory that is specced up to 3000F is going to be 60% Al oxide or higher. I believe resistance to flux depends the binder that is used. Refractories with a high phosphate binding do better when exposed to flux.

I am going to try using an SS drip pan on the floor to catch liquid flux when welding. We'll see how that works. Often I am able to weld outside the forge by making a small chamber just at the mouth.

[Sweany]

I use some fiberfrax products along those line.

My experience with lineing horizontal forges

Definitly wet the wool before putting on the refrac, I usually slice the refrac (1/2" or 3/4" and lay it on in sheets, wet each side (water won't hurt it)of the refrac put in place and then wack it with a dowel rod. taper and ovelap the seams
I only put the refrac on the bottom 2/3rds or 1/2 of the forge.

I've made a slurry or slip out of the refrac and coat the top half of the forge.

My last forge I used wet kitty litter to cover the wool, I haven't used it much yet but in three four frings it is holding up OK.

The refrac on the top half of the forge usually wants to come down after a while if it's heavy.

I get more heat out of the forge with the top half coated, and more durability with the refrac on the bottom.

my .02 your mileage may vary

[maddog]

... I usually slice the refrac (1/2" or 3/4" and lay it on in sheets, wet each side (water won't hurt it)of the refrac put in place and then wack it with a dowel rod.

Sweany, thanks for the info. I'm with you on everything except "slicing" the refractory. I am using Mizzou, a castable. I was planning to trowel it on to the wool. I could mix it up very stiff like a plastic and slice it. Is this what you have in mind?

Added later:

I am bearing down on this detail because it has to do with my main concern, that the refractory will cure into a sound shell without cracks.

[monstermetal]

I have built several forges where I put a wool blanket in a bucket of castable mixed soupy and worked it into the wool. You end up with a heavy layer that makes the blanket set up hard. Very durable You have to be able to hold the blanket in shape while the castable sets up

[maddog]

I have built several forges where I put a wool blanket in a bucket of castable mixed soupy and worked it into the wool. You end up with a heavy layer that makes the blanket set up hard. Very durable You have to be able to hold the blanket in shape while the castable sets up

hmm intersting idea. Doesnt the wool just collapse and turn into a soggy mess with no air in it?

I plan to wrap it around a carboard tube while it sets up. May even fire it that way.

[monstermetal]

hmm intersting idea. Doesnt the wool just collapse and turn into a soggy mess with no air in it?

I plan to wrap it around a carboard tube while it sets up. May even fire it that way.

Nope... you mix the castable into a thick mud and then work that into the wool.... no forms, just pack it into the forge... I weld a couple of small nails to the forge shell to hold the wool up while the castable sets.. Its worked quite well for me, I have one forge thats going on 7 years with the same liner (its been patched and repaired but never replaced)

[maddog]

Nope... you mix the castable into a thick mud and then work that into the wool.... no forms, just pack it into the forge... I weld a couple of small nails to the forge shell to hold the wool up while the castable sets.. Its worked quite well for me, I have one forge thats going on 7 years with the same liner (its been patched and repaired but never replaced)

I will try that today. Thanks

[maddog]

Well I made the chamber by troweling 1/2" of mizzou onto the surface of some moist kaowool and wrapped the whole thing around a 4" cardboard tube. After the initial slow firing process to cure the refractory, I coated the inside with two coats of Plistix 900. Since then I've had the forge up to welding heat a few times. There is no sign of cracking. There are no holes in the chamber. Forge gets to low welding heat in about 10 mins from cold. Tomorrow I will coat the interior with ITC100.

I plan to build a 3" dia forge using the same method.

Mizzou is very resilient and very tolerant of different casting techniques.

I initialy tried to do Monster's method but I couldn't get anything that looked convincing so I went ahead and troweled on the Mizzou.

Thanks for all the suggestions.