Kaowool....DANGEROUS????

[sierevello]

I see Kaowool is mainly asbestos. Isn't this stuff dangerous when heated inside a furnace or is it buried in the refractory? Also, I am sure some care needs to be taken when cutting it. Thanks, Steve

[Roy]

I certainly don't know where you came up with Kaowool being mainly asbestos, as it certainly is not. Its a replacement for asbestos and is mainly a ceramic fiber, actually a vitreous aluminosilicate fiber, totally manmade. Other than any precautions related to the general handling of fiberglass type insulation as far as skin irritation or using a dust mask when cutting, its as safe as it gets. Read the MSDS on it....contains no asbestos or asbestos byproducts. depending on the furnace it could be buried or left exposed, but it does not wear well, and is usually coated with a refractory coating such as ITC to make it more durable. It can be placed behind castable refractory or bircks as well.

[sierevello]

Thanks for straightening me out Roy...It was about 4am when I was reading the web page on Kaowool and must not have seen the words "Asbestos Replacement". Thanks again for the heads up. Would it be good to use the Kaowool in an electric furacne, say coated with the coating you were talking about and then burying it in the refractory? Thanks in advance, Steve.

[Roy]

I would use the soft type of refractory bricks and groove them before I would bury the element. Its possible from what I have been told for an element to overheat if buried in refractory. Can't swear to it but thats wghat I have been told. It was all brought up when the topic of using a typical Gingery electric furnace came up as to being carefull with the exposed elements as they can produce a shock high enough to kill you and its a good practice to shut it off before adding metal and removing the crucibnle etc etc. It was suggested to bury the elements, and it was quickly brought up they may run hot in use, and actually overheat and burn out. Probably getting the element to stay in place in kaowool would be a chore anyhow, its got the consistency of what a stack of tissues would be. The ridgid or board type is about like the fiberglass ceiling tile panels, and that would probably work better than the bat type with holding the elements in place. Soft refractory brick are easy to cut, and probably cheaper to buy than KAOwool, and certainly easier to work with with getting the grooves etc in for hollding the element in the walls than castable refractory. I would make it with soft refractory brick and coat the brick if necessary, and if need be, use the hard ridgid Kaowool board insulatin on the outside. Kaowool will take the heat just not able to handle abuse or wear very well. Itb also makes a great lightweight lid for a crucible or other furnace. Just cut it into strips about 3 or 4 inches wide, and wrap it up like a big roll of toilet paper, leaving a core in the center for the exhasut vent. When you get it to the desired size use a piece of steel banding material or wire to wrap aropund it and hold it in shape. Can't get much lighter or efficient.

[sierevello]

Roy...Could I use the brick and then put the kaowool behind the brick and then ram refractory in behind that. Would the kaowool increase the efficiency of the furnace that much to warrany using it. I would probably use the sheet type. Thanks for the help. -Steve

[Roy]

Well you could but you would compress the Kaowool in the process of ramming in the ram type refractory.

I made a furnace (propane_ that used three different refractory materials. Castable, Kaowool, and ram type. I can't say its any more efficient than my strictly castable, but evey degree you can retain is to your advantage. I could not really make a fair comparison as the 3 ref type furnace is larger than my other furnace. I rammed the refractory against the shell to start, laid in some kaowool, and then made a liner out of the plastic corrugated sheets that you see politicians making signs out of., and placed it against the kaowool, and then poured the castable. When it cured, and I fired it up the castable got hot enough to melt out the plastic corrucgated liner. The liner gave more foot print so the kaowool did not compress as much , I hoped that was what would happen anyway, and it also kept the water from the castable from soaking into the kaowool as well. It has held up fine so far and I have quite a few long hot melts in it. I would use ramable and the brick and not worry abnout the kaowool. I do not know what your brick is rated for, but if you backed the brick with a castable or ramable in the 2400 to 2600 deg range you should have some good insulation quality to it. If I was to use kaowool, I would probably use Brick, ramable and then sheet kaowool between the ramable and the shell of the furnace. But you should be fine without it. Might want to consider using it for a lid as in the above post, as its great for a nice lightweight lid.

[jmscott]

The main advantage of ceramic fiber is its light weight and that it doesn't hold heat like brick. Furnace is quick to heat and cool off. Disadvantage is that it is easy to damage.Not usually repairable like castables. It is great in overhead use and on tall side walls. There is a foamed version which is used where piping enters and leaves furnaces. It is usually too expensive for small users.

[chub]

I usually put a s/s wire mesh over the blanket and coat with a thin layer of refractory cement the wool and mesh are held on by s/s welded pins which is then cliped to hold the wool and mesh on before cement stagger your layers of blanket when installing it.