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hershey8

Looking For Recipe For Light Weight Kiln Bricks For Electric Kiln

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I am refurbishing a Paragon snf24 kiln and need a few light- weight bricks. $12.50 plus shipping isn't going to cut it! So I'm wondering if anyone has any info on how to make your own grooved (for elements) light weight refractory brick. I can cut the brick and can make my own grooves(channels) but need a recipe for the brick. If they need to be press formed, I have a 26-ton log splitter that I can adapt for the job.  I will be making and replacing all of the element this week, and it's the perfect time to replace damaged bricks. Thanks,     Hershey8    aka  john autry

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I'd try mixing Wollastonite and Phosphoric Acid and pressing it into a mold with the groove indentation already in the mold.  It becomes hard after 20 minutes or so and cures fully at 550F.   http://cone6pots.ning.com/photo/wollastonite-phosphoric-acid

 

It's generally porous enough to stick kiln pins into and stable up to 3,040 F.   But you can mix in pumice stone or soft fire brick ground up to end up with something a little less strong and easier to stick pins into.  These are slightly different starting ingredients to kiln repair cement you'd buy from your kiln manufacturer.

 

Someone mentioned a calcium-phosphate or magnesium-phosphate cement at Home Depot that may be less expensive.  I think most are  two part cements mixing Ammonium Phosphate with Magnesium Oxide or Calcium something.  But that's what you're looking for, a phosphate cement.

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Norm, do you know what the recipe is for IFB(soft bricks)? I have several barrels of broken small pieces from rebuilding a gas kiln and like john thinking about DIY soft brick.

I was hoping to crush up the broken soft brick and add some clay(fire clay?),sawdust and a binder make fire for replacement bricks like John was thinking of.

The patch would be good for smaller areas  but possibly too expensive for larger projects.

Thanks Wyndham

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Most all brick recipes I know of are for hard brick, or something heavier than IFB anyway. All of the recipes I have seen are some combination of fireclay and grog, some with a little added ball clay, some with a little added calcined clay.The key to IFB is all the little air pockets. To do this on your own you'd have to add in some sort of organic material, then fire the bricks to burn them out. Fine sawdust could work, or flour (I used this for wood kiln wadding), or any fine particle material. As to how much organic material, that'll take some testing. I'd start at about 30% by volume and go up from there. I've heard of people using pearlite, but it's not all that fine, and would leave much larger air pockets than traditional IFB. This is going to take a lot of testing, and even then you may find it doesn't perform as well as real IFB, which could mess up the performance of your kiln. Personally, I'd bite the bullet and buy some bricks. Either way, you're not going to get it done this weekend, as the bricks will probably need to dry for a couple of weeks before firing or if you buy some they'll have to ship.

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Making IFB the way they're actually made requires a large kiln to make kiln brick, which sort of defeats the purpose in most repair circumstances.

 

Norm, do you know what the recipe is for IFB(soft bricks)? I have several barrels of broken small pieces from rebuilding a gas kiln and like john thinking about DIY soft brick.

I was hoping to crush up the broken soft brick and add some clay(fire clay?),sawdust and a binder make fire for replacement bricks like John was thinking of.

The patch would be good for smaller areas  but possibly too expensive for larger projects.

Thanks Wyndham

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Right now I'm waiting for the glaze buckets to finish thawing out so I"m in no rush.We've got some places that mfg furniture near by so I've got the sawdust.

Most of this kinda stuff fall into the category of "Learning" not so much practical.

One of my concerns was the shrinkage of raw clay and the ground up firebrick. I'm thinking that about 50/50 fireclay/calcined (glomax)clay then sawdust but does there need to be a binder like the Wollastonite and Phosphoric Acid mix, Norm, that you mentioned above.

After the propane prices come down this spring(hope) I have a 50 cu ft stacking space gas kiln to fire the bricks.

I'd likely use them for a secondary layer or in the exit flue or even the sub floor in a new kiln.

Just one of those ideas for a cold day waiting for the water to heat up so I can start turning.

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I will add that you need some organic to burn out the and leave air space.It snot worth the hassle to make them I feel

Why not just order a  case of K23's they come 12 to a box now-They can be had cheaper than 12$ per brick.You just need to find the right source

You can router the groove or saw the groove thats easy.You will need breathing protection while working them.

Mark

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Making IFB the way they're actually made requires a large kiln to make kiln brick, which sort of defeats the purpose in most repair circumstances.

 

Norm, do you know what the recipe is for IFB(soft bricks)? I have several barrels of broken small pieces from rebuilding a gas kiln and like john thinking about DIY soft brick.

I was hoping to crush up the broken soft brick and add some clay(fire clay?),sawdust and a binder make fire for replacement bricks like John was thinking of.

The patch would be good for smaller areas  but possibly too expensive for larger projects.

Thanks Wyndham

 

 

Which came first, the kiln or the bricks?

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I will add that you need some organic to burn out the and leave air space.It snot worth the hassle to make them I feel

Why not just order a  case of K23's they come 12 to a box now-They can be had cheaper than 12$ per brick.You just need to find the right source

You can router the groove or saw the groove thats easy.You will need breathing protection while working them.

Mark

Mark,I just found a source for k-23's @ $2.30 per brick. This morning I took a piece of old k-23 and touched a router with a carbide bit to it.....wow. If I can come up with the right configuration of router bits this should be the ticket! The groove I need looks like a t. So, I'll probably make a strait vertical cut followed by a straight horizontal cut. I think I have those bits, though I may have to modify one a little. If it's not perfect it should still work. I am amazed at how easy and clean this stuff cuts with a router bit. Vaccuum port is going to come in handy on this project. Thanks Mark.    john

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Thanks to all  for  all of your information.  Since I was able to find a source of k-23's for $2.30 per brick, I think I'll just let the brick people make the brick. Cutting and grooving the brick  should not be much of a problem; this stuff cuts like butter. Thanks for your thoughts and ideas. Mark C. thanks for k-23 idea.

                                            

                                                                                                    john autry

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Cuts like butter, but will dull your blades quickly. Use multiple vacuums if you have them, preferably with HEPA filters. Wear a mask. It's going to make a huge mess. Do your best to keep the dust out of your power tools, because it will ruin them. Brick dust is incredibly abrasive.

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Cuts like butter, but will dull your blades quickly. Use multiple vacuums if you have them, preferably with HEPA filters. Wear a mask. It's going to make a huge mess. Do your best to keep the dust out of your power tools, because it will ruin them. Brick dust is incredibly abrasive.

 

 

On a scale of Adele to Fran Drescher, how abrasive would you say it is?

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Cuts like butter, but will dull your blades quickly. Use multiple vacuums if you have them, preferably with HEPA filters. Wear a mask. It's going to make a huge mess. Do your best to keep the dust out of your power tools, because it will ruin them. Brick dust is incredibly abrasive.

 

 

On a scale of Adele to Fran Drescher, how abrasive would you say it is?

 

 

That's not a very wide range. I'd say Gilbert Gottfried.

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Cuts like butter, but will dull your blades quickly. Use multiple vacuums if you have them, preferably with HEPA filters. Wear a mask. It's going to make a huge mess. Do your best to keep the dust out of your power tools, because it will ruin them. Brick dust is incredibly abrasive.

 

 

On a scale of Adele to Fran Drescher, how abrasive would you say it is?

 

 

That's not a very wide range. I'd say Gilbert Gottfried.

 

Well, I was thinking of Adele at the low end.  She's the first, good, singer that came to mind.

 

And Wow, Gilbert Gottfried abrasiveness!  Shouldn't that require several layers of protection?

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I went to Home Depot and purchased a $99 table saw for the  cutting of IFB on my 50 cu ft kiln rebuild.Even with a bag around the motor area to keep dust from the bearing, it was shot after that build.

 

You might try and find a cheap router at a pawn shop or Harbor Freight.

Thanks Norm for the PDF, that's got a lot of good info in there.

Your Wolastonite Phosphoric acid mix might be a good cement if one wanted to  make a thicker IFB  by cutting one brick lengthwise and "Gluing" it to the back of another brick making a (slotted) IFB a bit over 3.5 thick.

Another potter and I have been discussing making a more well insulated  cone 10  electric kiln for crystalline firings. We both have kilns  that need to be replaced in the next year.

Might have some testing soon as the weather permits.

Wyndham

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We had. Guy in grad school who tried to fire a mass of home made bricks in a newer cone 10 glo bar kiln. The mass radiated back to the globars for a melt down costing the kiln. Some times you need to just accept these things but the professors at the school were out a very expensive kiln.

 

glad you found a source for IFB.

Marcia

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i've seen a few recipes and most of them have a rather high percentage of calcined clay in them (over 50%).  I have also been told that kiln furniture needs to be calcined hotter than the temp you'll be firing to or you risk additional shrinkage/cracking.  I'd probably experiment with fireclay and ball clay as the clays, then add in a combustible filler like sawdust, vermiculite, or cellulose blow-in attic insulation.

 

where did you find soft brick for so cheap?

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I have an old radial arm saw I ( a junker from sears I inhereted) used with a carbide 14 inch blade from Harbor freight  to make my own arch bricks. It dulls the blade but I cut the whole arch and then loaned the saw out for others to cut their own arch-its been on loan for years.

I set this all up out side with a shop vac but its still so dusty I wore a really good respirator . The other thing is the jig I made to do this safely as thats a lot of blade to be near.

The Jig is the whole deal really. The carbide bit will be toast when your are done so factor that cost into the deal.

Mark

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I found the brick at Larkin Refractory in Lithonia, Ga.  Haven't picked it up yet, busy making elements. k-23 (2300F) 2.30 per brick. They also have hotter brick 2600f,2800 f, and 3000 f., $3.00,$4.20 and 8.55. I have a garage sale $15  router and some cheap  carbide bits that should be fine for this. Also have an old radial arm saw and a bunch of not-so-good carbide blades. Perfect! I believe I'll take this project outside, wear a respirator and blow the dust away from me with a fan. Thanks again for all the info and advice!  ja

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That's the stuff!  http://shop.clay-planet.com/kast-o-lite-30-li-plus.aspx

 

Most cements harden by soaking up water, but that's no good for kilns - as heating turns bricks made of Portland cement or Plaster of Paris back into dry powder.

 

With this cement, adding water merely allows the dry Phosphate chemical to react with the Alumina and or Calcium/Magnesium components.  The water steams-off or evaporates completely leaving the hardened brick.  It's a chemical reaction so it's best to add pure RO water, so you're not adding a bunch of the wrong minerals.

 

Someone mentioned finding a slightly different product at Home Depot, but with that you probably have to mix it up with crumbled kiln bricks.  Better to buy the right stuff.  Leave firing IFB bricks to a factory set up with the right kiln to do it.  Using a chemical reaction to make kiln bricks is way easier and safer.  The IFB brick factory ultimately uses their process because it's less expensive.

Sounds like you've got the solution with the affordable bricks but there is also Litewate castable

Cast your own softbrick any shape you need : about a buck a pound dry:

http://www.sheffield-pottery.com/U-S-LITE-WATE-23-insulating-castable-p/lvusl23.htm

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Would this stuff make a good kiln lid? One day in the near future my kiln lid is going to give up and I really want to cast one. Whoever made mine made some bad design decisions as the peep hole in the top really weakened the bricks structure. It is slowly disintegrating and cracking from the peep hole.

 

One problem I can see is managing to fire the thing to create the holes in the brick. Just putting it back onto the kiln and hoping for it to fire would probably not work  :(

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Yes, phosphate cements do make good kilns, but you may still have to use the cement to make bricks as a single cement pour might have expansion-contraction/cracking problems.  Just as with the Monel jacket around electric kilns, there may need to be additional structural material.

 

Marcia Selsor or some other kiln or oven builder would know a lot more.

 

 

Would this stuff make a good kiln lid? One day in the near future my kiln lid is going to give up and I really want to cast one. Whoever made mine made some bad design decisions as the peep hole in the top really weakened the bricks structure. It is slowly disintegrating and cracking from the peep hole.

 

One problem I can see is managing to fire the thing to create the holes in the brick. Just putting it back onto the kiln and hoping for it to fire would probably not work  :(

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There are a couple of problems you could run in to using a castable product for a kiln lid instead of IFB. First, as Norm mentioned, can a large flat disc of castable handle the expansion and contraction without cracking? Even with a metal band around it, if it cracks it's done. Lids have to be structurally sound.  Second, would it insulate as well as IFB? The power needed to heat up an electric kiln is calculated based on the insulation value of the IFB's. If the castable does not insulate as well, especially in an area as important as a lid, it could affect the ability of the kiln to function normally. Third, what does it weigh? If it's heavier than IFB, then you may have to re-engineer the hinge system on the kiln.

 

This Kast-O-Lite product is available in lower temp versions, like 2600F and 2300F. And just like IFB, the lower the max operating temp, the better the insulating value. In looking at the specs on the Kast-O-Lite vs. IFB, the castable is heavier, more dense, and more thermally conductive than the IFB. Probably not a good choice for an electric kiln lid.

 

Castables definitely have their place in kiln building, however they are typically used in specific areas, rather than for the whole kiln. That said, I have seen several gas kilns made totally of castable, of catenary arch design, used for salt firing. But they do tend to crack a lot since they are monolithic, and an outer layer of insulating material goes a long way to improve their efficiency. Castable also tends to be quite expensive compared to IFB. Personally, I have used castable products to make the throat arch in a wood kiln, for lining fireboxes in soda kilns, for making the key in sprung arches.

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