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Post by etownandrew on Dec 26, 2017 16:43:24 GMT -8
I have been making some test bricks using shredded rockwool as the fiber source additive. However, I have been having a hard time getting the blanket rockwool to break up into fibers. I have tried mixing clay slip with little rock wool pieces using an electric drill with an attached mixer and that has not worked to break up the rock wool. I'm about to try and switch to some other fiber (not sure what) but thought I would check to see if someone has a better method.
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Post by coastalrocketeer on Dec 26, 2017 17:34:46 GMT -8
I was able to get it to shred with a single kitchen mixer end on a drill... But was working with a lot thicker mixture than clay slip.
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Post by smartliketruck on Dec 27, 2017 11:32:01 GMT -8
If your rockwool is like Roxul panel insulation I found some lye in the mix will help break down the slightly water resistant adhesive. Of course heat will also break it down but I've not experimented to see what the lower threshold is.
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Post by etownandrew on Jan 27, 2018 12:53:44 GMT -8
Based on your suggestions, I ended up getting a hand held kitchen mixed for use in my shop. It worked well to shred the rockwool. (Note that at this moment I am using housing insulation to reinforce the clay that is only rated to 2000F. It is not intended for direct heat exposure in the riser.)
My process was to tear up the rockwool into small pieces that were about 1" to 2" in size. Note to wear a respirator and rubber gloves. At that point I could either add it directly to a wet clay mix and it would tend to dry out the clay as the rockwool needs moisture. If my clay mix did not need to be dried I can also mix the rockwool in a pail of water until they look shreded. It helps to initially saturate the rockwool with water before beating with the mixer. Then using gloved hands strain out the shreded rockwool and squeeze out excess moisture. I then put the wet rockwool into my bucket of wet clay. At that point I can use the mixer again to evenly distribute the rockwool throughout. I think that it is a little bit easier to initially shred the rockwool in a bucket of water. However, it might also work fine to saturate the rockwool with water and squeeze out the excess and then do all the shredding/mixing right in with the wet clay. I didn't try that variation.
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Post by patamos on Jan 28, 2018 17:46:20 GMT -8
Could be it is just a matter of clay slip to rock wool ratio. I use a heavy duty drill with a egg beater mixing bit. No problems.
Thicker slip helps, and adding more rockwool creates a viscosity enough to fully blend the contents.
Adding sand (if you are not going for high insulation) also helps things to blend
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