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neilestrick

Member Since 04 Oct 2011
Offline Last Active Yesterday, 09:06 PM
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#51959 Looking For Recipe For Light Weight Kiln Bricks For Electric Kiln

Posted by neilestrick on 08 February 2014 - 09:27 AM

 

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.nin...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.

 

Norm, I am getting closer to converting the pieces/parts from two old electric kilns into a propane, updraft gas kiln... very similar to this project: http://codyopottery....irth-of-my.html   After looking at the hole in this guy's kiln where the propane is introduced, I'm considering molding a pipe that would slide through the rectangular cut in the side of the kiln, basically rectangular profile pipe on the outside but round in the center where the gas flame would pass through.  Would this Wollanstonite-Phosphoric Acid mixture work for this? If so, what sort of mold release would you recommend?

Thanks,

Paul

 

 

Burner ports are a great place for castable.




#51844 Looking For Recipe For Light Weight Kiln Bricks For Electric Kiln

Posted by neilestrick on 06 February 2014 - 05:31 PM

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.




#51764 Looking For Recipe For Light Weight Kiln Bricks For Electric Kiln

Posted by neilestrick on 05 February 2014 - 03:00 PM

 

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.




#51761 Looking For Recipe For Light Weight Kiln Bricks For Electric Kiln

Posted by neilestrick on 05 February 2014 - 02:35 PM

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.




#51747 Looking For Recipe For Light Weight Kiln Bricks For Electric Kiln

Posted by neilestrick on 05 February 2014 - 12:03 PM

 

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?




#51733 Stuck Lids.....

Posted by neilestrick on 04 February 2014 - 11:59 PM

A little alumina on the lid seating will solve all your problems. Just mix it in your wax resist. The only way to ensure that a lid fits perfectly is to fire it on the piece. While much of the time you could get away with firing them separately, those times that they warp will inevitably be on the most important pieces. My concern would not be with the lid warping, but rather with the lip of the pot warping. If the lid fits the way it should, it would only take the slightest movement to screw up the fit.


#51685 What Kind Of Kiln Shelves To Use?

Posted by neilestrick on 03 February 2014 - 11:36 PM

Just got 6 more 14x28 Corelite shelves for $48 each. Nice and light, although slightly thicker than my other shelves. I've been using a set of them for a year now with no warpage at all.




#51648 How Much Difference Does A De-Airing Pug Mill Make?

Posted by neilestrick on 03 February 2014 - 11:03 AM

The other reason I think is that feeding bagged clay through pugger allows for the clay to re orientate from the 8x8 block down to a smaller workable pug. Clay in 25 lb bags start to setup some and you also need to change the spiral that the larger pug mill introduced.

Because some clays like Bmix or Loafer Glory can be quite firm, the pugger can change the clay to soft plastic throwable clay by going through the pugger, same as wedging does

Wyndham 

 

I often hear people talk about the spiral of the pugger, and have never found it to be an issue. By the time you cut up your clay and make it into balls, you're not dealing with a total spiral, but a small section of one. And if you wedge, you're creating a new spiral. And if you cone the clay during the centering process, any spiral that existed is gone, and replaced by a new spiral from the wheel.




#51647 How Much Difference Does A De-Airing Pug Mill Make?

Posted by neilestrick on 03 February 2014 - 11:00 AM

Mixers mix on a large scale, getting dry areas and wet areas combined into a consistent mix, but full of air, too. But for clay particles to bond well, they cannot have tiny air pockets between them. Each particle must be throughly wetted, with just a thin layer of water between each particle, as we discussed in our recent plasticity discussion. This is why non de-aired clay is often referred to as being 'short'. The clay particles don't bond as well, and the clay tears easier and doesn't hold form as well during the throwing process.




#51587 Brushing On Glaze?

Posted by neilestrick on 02 February 2014 - 01:32 PM

Make a gum solution of 2 tablespoons CMC gum to 1 gallon of warm water. Also add 1/4 teaspoon copper carbonate as a preservative. It's not enough to affect the color of the glaze. Add the gum and copper to the water and let it sit overnight, then blend it up really well with a stick blender. Use this solution for 1/3 of the water when making your glaze tests. I have not found bleach to work well as a preservative. Personally, I like this mix better than Xantham gum. Try the mboth and see what you like best.

 

When I worked as a tech for a clay supplier, we used a mix of CMC and Vee-Gum T for our brushing formulas. Vee-Gum T is kind of pricey, so for testing your glazes it's not really necessary.




#51308 Uneven Top Edge And Thickness Of Wall On Pots

Posted by neilestrick on 29 January 2014 - 04:38 PM

Walls that are not even thickness all the way around can be caused by several things. First, it can come from the clay not being centered properly. Make sure yo cone it at least 3 times to get a smooth consistent ball and don't have any wobbles. Second, it can be from opening off center. Make sure your arms are anchored to your legs and your hands are anchored together when you open. But if you're centering and opening on center, then it can be caused by starting your pull before you have established the pinch all the way around the pot. So when you do a pull, make your pinch at the bottom, right against the wheel head, with your outside hand, and let the wheel go around a couple times before you start pulling up.




#51283 Having A Kiln Outside ?

Posted by neilestrick on 29 January 2014 - 10:31 AM

When constructing a cover for your kiln, remember that rain doesn't always fall straight down.




#51255 How Much Do You Make Before Bisque Firing?

Posted by neilestrick on 28 January 2014 - 09:59 PM

The firing cost is not so different if it's full or empty. If you have to fire due to a deadline, then do it. But if you're just impatient, suck it up and make some more pots.

 

technically-the-glass-is-always-full.jpg

 

 




#51122 Crack In Glazed Vase

Posted by neilestrick on 27 January 2014 - 10:53 AM

That curve is probably the thinnest part of the part, and also the least compressed, so it was the natural place for it to crack. It may not have happened on a perfectly even cylindrical form, but clearly there are some stresses at work there just waiting for a weak point. I assume Benzine as used this glaze combo before? This is a good lesson in how the quality of construction is important beyond just getting it to stand up long enough to get it off the wheel.

 

I had this happen on a pair of lamps I made last year, with a glaze combo I had used many many times. I decided on that pair that I didn't need to glaze the inside since it would never show, and three days after firing the glaze ripped them apart.




#51068 Electric Kiln Controller Issue

Posted by neilestrick on 26 January 2014 - 06:30 PM

Yeah, I hate to say it but it was probably user error. As Norm said, if there's a review button, always hit it after you start the kiln to make sure you did what you think you did. After 20+ years of firing kilns, I still us the Review button every time I fire. You can also use it after you fire to see what you did.

 

It's also possible there was a controller or thermocouple issue, but that is rare. However make sure your controller is set for the type of thermocouple you are using.