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Member Since 04 Oct 2011
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#66861 What Is Causing The Black Zits In My Glaze?

Posted by neilestrick on 29 September 2014 - 11:57 AM

I fire a few thousand pounds of 112 in my studio every year, and occasionally get some pinholes/craters/globs like that, but only on the glazes that I know to be a bit unstable, like fake ash glazes. Firing your glaze to cone 6 may be just what it needs to settle down a bit.

#66668 I Got 84 Kiln Brick But A Reduction Ain't One.

Posted by neilestrick on 26 September 2014 - 01:35 PM

In theory a thinner wall can work. The round updraft kilns like the Olympic Torchbearer models function with 3" brick, after all. However they have the benefit of being strapped together by the outer sheet metal skin, which keeps gaps and air leaks to a minimum. And even then they are very inefficient and uneven. If you were to dry stack IFB in a 3" wall configuration as a rectangle it would be quite leaky, even with angle iron on the corners. All the little leaks ad up to quite a bit when dealing with high fire. In theory it will work, but in practice I think it won't. At the very least you would need to mortar the joints. If you search the forum you'll find many many posts about people trying to get to high fire temps with shortcut kilns and they always have problems. If you're looking for something to tinker with, and have the time and money to waste on something that may or may not ever work, then by all means have fun with it and give it a try. Tinkering is one of my favorite hobbies, too. But if you're trying to build something on a budget and need it to work, then wait for more brick, like several hundred, and build a proper kiln. Even if you just got another 150 and invested in some rigid board for the outer layer you could have a nice little functional kiln.


I built and fired a small salt kiln in grad school that was big enough for one 12x24 in shelf- 27 inches tall with 27" x 22.5" interior. It was a simple cross draft with a hole in the top corner for an exit flue, and one power burner. The top was kiln shelves covered with firebricks. It fired like a charm and gave great results. But even that little kiln, which I wouldn't go any smaller than, took 500 bricks.

#66666 I Got 84 Kiln Brick But A Reduction Ain't One.

Posted by neilestrick on 26 September 2014 - 11:43 AM

There's no such thing as enough bricks.....

#66637 Does Use Of Masons Stains Require Reformulation Of Formulas?

Posted by neilestrick on 25 September 2014 - 08:34 PM

There are, or course, exceptions to this rule, but generally speaking a colorant will not effect the melt of the glaze. Different colorants require different percentages, as some react much more strongly than others. 0.5% cobalt carb will give you a strong blue, but the same percentage of iron oxide won't do much at all. There are also limits to how much of any one colorant or oxide can be safely used in a glaze. And certain colorants require specific ingredients in a glaze in order to achieve the desired color.

#66636 Foot Impression?

Posted by neilestrick on 25 September 2014 - 08:28 PM

If it's slumping over the foot in the firing, then you need to either thicken the bowl in that area or fire a little bit lower.

#66620 An "office" Kiln

Posted by neilestrick on 25 September 2014 - 02:47 PM

If you're going to fire pottery, get a kiln that's made for pottery, not glass. That said, this sounds like a less than ideal situation. I would take a lot more classes and get more familiar with the firing process before you buy anything. Then you can make an educated decision.

#66554 Used Car, I Mean Kiln Shopping

Posted by neilestrick on 24 September 2014 - 09:00 AM

If it has the more 'modern' controls with Fireye scanners and spark ignitors, if the pilot is unhooked then it's all unhooked, since the burners won't light without the pilot being proven by the Fireyes. It could just be an old manual system, though, that predates those, but at 30 years old I would expect it to be more modern than that. If it's literally just the pilots, those are a cheap replacement. But typically pilots are connected to a more expensive safety system. No telling what he's done.


The safety systems are the only automatic parts. You still have to adjust the air, gas and damper manually.

#66533 Dry Glaze

Posted by neilestrick on 23 September 2014 - 07:20 PM


If you're dealing with non-functional work, then all the rules for food safety are unnecessary. if you don't want to work with barium, a glaze can be made dry by increasing the alumina content to the point that it's no longer melting completely and forming good glass. This is essentially how underglazes work- not quite a glaze, but not a slip. You could even do something like a line blend of a glaze and calcined kaolin. Another option is a high magnesium glaze that is slow cooled to create a matte surface.

Is there a discernable difference in the mattes obtained, Neil? Durablility? Appearance? The effects on the colourants would come into the picture too.



Magnesium mattes are a great way to get a durable matte surface, and you can control the degree of matteness via cooling cycles. Dry mattes that are under-fired are not generally durable or food safe because they're not fully melting and forming good glass. I would think that colorants would be more vibrant in a fully formed glass, but since you're not dealing with food safety in under-fired mattes, you could just put a ton of colorants in to get deep colors, like they do with underglazes.

#66431 How Many "hand Builders" Here?

Posted by neilestrick on 20 September 2014 - 12:11 PM


#66413 Speedball Artista Pottery Wheel - Good Or Not ?

Posted by neilestrick on 20 September 2014 - 08:51 AM

It's a great little wheel for what it is, but not necessarily something you want for a full time wheel. If you have room to set up that wheel, then you can probably find the space for a regular wheel. Electric wheels really don't take up that much space, and studios don't need much floor space. You won't be walking around a lot as you work! I once had a kick wheel, two tables, a large oval electric kiln, a round electric kiln, 20 big tubs of raw materials, all my clay, slop buckets, shelving, everything, etc. in an 8x15 studio. Very little floor space, but very organized and functional.

#66236 Repair Bisque Piece?

Posted by neilestrick on 16 September 2014 - 08:26 AM

Slow down the first several hundred degrees of your firing if you have thick spot like that.

#66109 Can A Candle Produce Enough Heat To Fuse Lid To Body?

Posted by neilestrick on 13 September 2014 - 11:54 AM

If the pot got hot enough in that area to melt the glaze, it would have been glowing, at least in that area. You can't get the inside wall of a pot that hot and not have the outside nearly as hot, too. The wall is not that thick. Even tack fusing glass needs 1300F degrees.


If the top of that pot was hot enough to melt glaze, the bottom would have been hot enough to burn whatever surface it was sitting on. In a 7 inch tall piece you could not get the top up to 2000F without the bottom getting up to at least many hundreds of degrees. Stick a 7 inch long tube of clay in the peep hole of your kiln till it glows and try to grab the cooler end. Plus the pot probably would have cracked if one spot was heating up that much.


Personally, I would not sell a candle holder with a lid. The odds of someone grabbing that lid while it's still hot are too great. Not only could they burn their fingers, but they could knock the thing over when they pull back their hand, spilling hot wax all over the place.

#65973 Kiln Lid Gap Help?

Posted by neilestrick on 10 September 2014 - 08:29 PM

Never set anything on the lid, especially heavy stuff. And never use a board as it can burn. And never use a battery because it can explode!

#65702 How To Get Started With Old Stains, Etc

Posted by neilestrick on 06 September 2014 - 01:36 PM

How do I mix small quantities of glaze? Everywhere I look the speak of 5 gallon buckets! To test the dozen glazes I have, I would like to make small batches of about 250 ml each. What ratio of water to dry glaze do I use?


For testing glaze I usually do 200 gram (dry weight) batches. Simply add enough water that it's the right consistency to dip a tile. The amount of water needed will vary from glaze to glaze. Use a stick/hand/immersion blender to mix it.

#65680 Questions About Firing With Peep Out

Posted by neilestrick on 06 September 2014 - 08:47 AM

If you're running a downdraft vent, all the peeps should be in whenever the fan is on.


You're probably right about the cooling time affecting the glossiness of the glazes. Slower cooling usually promotes matte surfaces. The vent will help speed cooling little bit, but you could always open a peep at the end of a firing to speed the cooling more. If your vent motor is mounted under the kiln, leave it running even with the peep open to keep the motor cool. If the motor is mounted away from the kiln you can turn it off when you open the peep. There will be a limit to how fast you can cool the kiln simply because it's bigger.