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Clifford Brewer

Home made castable refractory

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Any one here know a recipe that really works ???

the store bought aint cheap where I live (and I am) aside from the fact that I like to experiment with

DIY stuff, seems to me if it's sold on the market someone has to have experimented to develop it.

I know I'll get words about tried and true off the shelf stuff

but doin it yourself is to me anyway what makes it fun and then sharin with like minded people makes it complete...

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No recipe's but I hope someone else here can be of more help. I'll be watching this with interest.

Edited by Myles Mulkey

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No recipe's but I hope someone else here can be of more help. I'll be watching this with interest.

 

Thanks for the reply the site you posted before the edit was interesting

you must have edited it out while I was lookin at it.....

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Thanks for the reply the site you posted before the edit was interesting

you must have edited it out while I was lookin at it.....

Yeah I wasn't sure that was what you were looking for, so I didn't want to bog down your thread. Didn't know you had made it to my post yet. You are fast :ph34r:

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i dont know about "castable" but i read one that was 1 part fire cement 4 parts vermiculite

 

I've seen lots of ingredients (up to and including horseshit) so far on my search ratios and proportions are some times strange sounding too but it's the thrill of the hunt right ... ;)

Edited by Clifford Brewer

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Yeah I wasn't sure that was what you were looking for, so I didn't want to bog down your thread. Didn't know you had made it to my post yet. You are fast :ph34r:

 

Timing was coincidental I'm sure ..... -_-

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I just finished a wood-fired pizza oven using this hi-temp mortar mix.

1pt masonry lime

1pt portland cement

1pt fireclay

3pt silica sand

It might work in some applications but I doubt it would stand up to the same temperatures as the commercial alumina stuff

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I just finished a wood-fired pizza oven using this hi-temp mortar mix.

1pt masonry lime

1pt portland cement

1pt fireclay

3pt silica sand

It might work in some applications but I doubt it would stand up to the same temperatures as the commercial alumina stuff

 

Thanks Hank but ya lost me at the portland cement

due to the fact that it explodes at forge temps,It works OK for your app. and for low temp foundry furnaces. I need more heat capable stuff.... B)

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I've used Portland mixed with fire clay in kiln construction before (up to 2300 degrees for very long periods of time) and I've never heard of it exploding.

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I've used Portland mixed with fire clay in kiln construction before (up to 2300 degrees for very long periods of time) and I've never heard of it exploding.

 

I've been hit by cement shrapnel after heat exposure (OUCH !!!)

Maybe the mix with fireclay slows the reaction ?

and I've been told that portland cement reverses its bind chemically after a certain temp.

some times violently.

So not knowing too much and having some bad experience I lean toward caution and ask questions thank you for your input.

What ratio of port. and f clay and such did you use if I may ask ??

Again thanks for your reply

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i dont know about "castable" but i read one that was 1 part fire cement 4 parts vermiculite

 

Thanks Dylan I'll ad that one to the list B)

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I've tried DIY mixes, and none of them are as easy or as pleasant to work with -- or probably as durable, for that matter -- as the commercial stuff. Portland loses its bonding power at high temps as it dehydrates. The offgassing of steam can cause explosive spalling, although it won't necessarily do so -- e.g., if the Portland content is low and the matrix is porous. Still, beyond a certain point it isn't contributing any bonding power, although it may help flux the surrounding ceramics to get them to sinter at a lower temp. Too much Portland will cause serious fluxing problems and reduce the melting points of your ceramics too far, to the point that your "castable" turns into slag.

 

Commercial castables use bonding agents like calcium aluminate cement, which is much more suitable for high temps. If you don't have something along those lines, you're left with basically just ceramics, which are difficult or impossible to fire properly, through-and-through, in situ. If you don't fire your ceramics properly, they're liable not to be nearly as durable as you'd like. And the sorts of ceramics you'd want to replace a castable would have high pyrometric cone ratings (making them difficult to sinter) and would be very resistant to thermal shock. Most aren't, and a lot of the interesting ones (like mullite) that do resist thermal shock really well tend to form at extremely high temperatures -- so again, you have a problem of how to fire it properly to get what you want.

 

Most common ceramics also contain a lot of silica, which undergoes phase changes at various temperatures, accompanied by sudden volume changes which can cause cracking. (Google "quartz inversion.") Alumina doesn't have that problem -- but once you start looking at high alumina ceramics with minimal silica, you discover they're not all that cheap.

Edited by Matt Bower

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I've tried DIY mixes, and none of them are as easy or as pleasant to work with -- or probably as durable, for that matter -- as the commercial stuff. Portland loses its bonding power at high temps as it dehydrates. The offgassing of steam can cause explosive spalling, although it won't necessarily do so -- e.g., if the Portland content is low and the matrix is porous. Still, beyond a certain point it isn't contributing any bonding power, although it may help flux the surrounding ceramics to get them to sinter at a lower temp. Too much Portland will cause serious fluxing problems and reduce the melting points of your ceramics too far, to the point that your "castable" turns into slag.

 

Commercial castables use bonding agents like calcium aluminate cement, which is much more suitable for high temps. If you don't have something along those lines, you're left with basically just ceramics, which are difficult or impossible to fire properly, through-and-through, in situ. If you don't fire your ceramics properly, they're liable not to be nearly as durable as you'd like. And the sorts of ceramics you'd want to replace a castable would have high pyrometric cone ratings (making them difficult to sinter) and would be very resistant to thermal shock. Most aren't, and a lot of the interesting ones (like mullite) that do resist thermal shock really well tend to form at extremely high temperatures -- so again, you have a problem of how to fire it properly to get what you want.

 

Most common ceramics also contain a lot of silica, which undergoes phase changes at various temperatures, accompanied by sudden volume changes which can cause cracking. (Google "quartz inversion.") Alumina doesn't have that problem -- but once you start looking at high alumina ceramics with minimal silica, you discover they're not all that cheap.

 

Thanks Matt you are echoing much of what my search/study has been turning up

( ":><{P<:L$^&**&$ ). It's lookin more and more like I'm needing to bite the bullet and buy commercial stuff but one can always hope right ,,?? :D

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as to the cement... most of the homemade forge liner recipes used by the old timers included some kind of cement. The only reason why things made of cement explode at high temperatures is due to people using cement blocks that were made for something else and have trapped moisture and air pockets inside of them.

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I think the Portland to fireclay ratio was at least 1:5 maybe even richer on the fireclay. To be honest we used it as mortar in wood fired salt kiln construction and our joints were very thin. It's been along time but I'm pretty sure we also added sand. I would go with a commercial mix if you can't get hi temp furnace bricks, quartz inversion is a radical transition, both ways.

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I think the Portland to fireclay ratio was at least 1:5 maybe even richer on the fireclay. To be honest we used it as mortar in wood fired salt kiln construction and our joints were very thin. It's been along time but I'm pretty sure we also added sand. I would go with a commercial mix if you can't get hi temp furnace bricks, quartz inversion is a radical transition, both ways.

 

Thanks man this quest is interesting at least so far .... B)

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Cliff

 

Im just getting back from a Christmas trip with no internet and found this tread. I have been playing with a mixture of ground Kaowool and and South carolina red clay with a small amount of caulk tube fire place cement. It is holding so far. Not sure of the portions it more of a grandmas cooking method , add what you need to get the constancy you need. Not sure what the clay is like were you are from but this southern red clay is awesome. I will add the clay I use is packed full of mica. Im not sure if that makes any difference or not maybe Alan will stubble over this and help us out.

 

Kip

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Cliff

 

Im just getting back from a Christmas trip with no internet and found this tread. I have been playing with a mixture of ground Kaowool and and South carolina red clay with a small amount of caulk tube fire place cement. It is holding so far. Not sure of the portions it more of a grandmas cooking method , add what you need to get the constancy you need. Not sure what the clay is like were you are from but this southern red clay is awesome. I will add the clay I use is packed full of mica. Im not sure if that makes any difference or not maybe Alan will stubble over this and help us out.

 

Kip

 

Thanks Kip that sounds interesting but where I am clay is not readily available

I can find lots of blue clay where I grew up in the real Nor Cal,not sure if it will hold up to temp. or not, We do have an abundance of red volcanic cinderstone here that I'm going to play with as a grog in a mix experiment as soon as it warms up enough here to work with it using fireclay and furnace cement as a binder the stuff is very porus and came out of a volcano so heat should'nt de-stabilize it (I hope)... :unsure:

On another note, my childhood nickname is also Kip B)

Go figure !!! :D

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