Kristin Yount on fri 17 mar 06
Mark,
I live in Portland and we have a refractory supply company in town
called Haverson Walker. Whenever they have out of date materials they
give it away for free. Now you might end up with a 50lb paper weight but
90% of the time you get perfect castible that they can't sell. I tell
you this because I was building little kilns in my yard- mostly (I found
out later) to facilitate the melting of dirt but that is another story.
I tried different kinds of castible.
Of all the ones I tried the easiest one and the most effective was an
all purpose (meaning insulating and for forming walls) was this stuff
called MC 25.
It was easier to work with and didn't crack as much. It was fluffy in a
good way.
You should see if there is a refractory supply place near you and see
if they will give you a bag or two to sample. One thing is that you may
end up with a product that is meant to be shot out of a high pressure
hose onto a form of some sort after being tumbled in a proper mixer. .
This can make it tricky if you don't have those. I was slap toweling
onto a form. I ended up adding a lot more water than what was called for
but it worked out all right. So if you have a couple of bags of
different stuff you can see how it acts when you work it before you have
three pallets of the stuff in your yard moldering under tarps. (not me I
swear)
The best castible I ever made up was 1 wheelbarrow load = 50 lbs of
perlite, two-four good sized shovels of Portland cement and 15 pound of
sand and some ball clay ( what I had around) for luck. dry mix with your
shovel and drink one can of beer and then mix again..It is really
important you don't rush that part you have to wait for any castible to
set up. Anyway this mixture spread much more nicely and reminded me of
rice crispy treats even though it cracks a little it was nice and
fluffy. The stuff that comes in bags just didn't "go" as far for me. It
is like buying premade clay (one bag) or buying the parts (five bags).
It seems like more work but it is so worth it to get EXACTly the
properties you want.
OH and one more thing- whatever you do! Don't go to the masonry place
and buy High Alumina "fondue" it is definitely a fond-don't. It melts
like butter. Unfortunately I know. Yelch.
Yours!
Kristin Yount
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