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Member Since 04 Oct 2011
Offline Last Active Feb 10 2016 01:29 PM

#94183 Qotw: Right Or Wrong? Japanese Worldly Wisdom....

Posted by neilestrick on 13 October 2015 - 08:56 PM

I think this can be interpreted in several ways. If I understand this as it was meant by the Japanese, then perfection comes from the absence of ego, that there is perfection in selfless action. But when I first read it I thought it simply sounded like a slacker's mantra- why bother trying at all. As I thought about it more, I came to the conclusion that perfection becomes more difficult to achieve because we are pushing the limits of our abilities, but it doesn't mean we shouldn't still strive for perfection. It's not a reason to give up. Why not try to be the very best you can be? And it doesn't mean that less-than-perfect results aren't acceptable. Every attempt is a necessary part of the education needed to achieve perfection.

#94145 How Much Clay Per Inch?

Posted by neilestrick on 13 October 2015 - 10:28 AM

It's not a constant amount, because as pots get bigger they also get thicker, and the proportion of clay in the bottom vs. walls also changes. It also depends on how wide the piece is. I can make a 4 pound pot that's 14 inches tall or 6 inches tall.

#93958 Kiln Conversion Updraft Downdraft Chimney?

Posted by neilestrick on 08 October 2015 - 12:34 PM

Mid-range oxidation has come a long way in the past 10-15 years, and gained a lot of respect. Prior to that is was considered the realm of hobby potters, or was 'settled' on by folks who couldn't access a gas kiln. Colleges and universities worked in gas, and therefore it was considered 'better'. Many of our historical references were also high fire, like the Japanese and Chinese glazes that have become staples like shino, tenmoku, celadon, etc. The only people that were really doing any sort of glaze work in mid-range oxidation were the commercial glaze companies, because in general, hobby potters were not doing their own glaze formulation and mixing. Then along came the Mastering Cone 6 Glazes book, which gave hobbyists the knowledge and tools to start developing their own glazes. Combined with the increased strictness of zoning rules and building codes, the cost of gas, concern for the environment, and the development of digital electric kilns, more and more and more people have started looking at mid-range oxidation firings as a legitimate way to make pots.


We now have some really wonderful work being fired in electric kilns that is virtually indistinguishable from gas reduction work, or that is very good without looking like reduction fired work. I think the idea that mid range potters are always trying to mimic high fired reduction work is inaccurate (this is the 'up on my soapbox' section of this post). Personally, I'm just trying to make good pots with beautiful glazes, be they reduction-looking or not. I think we need to get away from this idea that pots have to look a certain way and get to the idea that pots simply need to be good, regardless of how they're fired. Do we add granular manganese to clay bodies so they look like reduced clay bodies? Yes, and no. They do look like that, but it's because it adds a richness to the glazes, not necessarily because we yearn to fire a gas kiln. It's kind of a semantics argument, but you get my idea. How about instead of saying it looks like reduction fired, we simply say that speckles look good, regardless of how they are achieved. If someone slow cools their gas kiln, do we say they're trying to mimic cone 6 electric firings, where slow cooling is very common? Many of the old school fuel-burning folks still have a snobbery about high fire reduction, but they need to get with the program, IMHO. The vast majority of kids graduating from college and grad school will not have the ability to build or buy or set up a gas kiln. Electric kilns are less expensive, easier to install, and don't violate most building codes. I'm not saying it's a better way to fire, but simply that for most people it's the most realistic option for firing.  A friend of mine who teaches at a university has recently switched the emphasis of his program to mid range electric firing for that very reason. He will still teach them to fire the gas kilns, but he wants his students to have the knowledge to do whatever method of firing is available to them when they graduate.


15 years ago I never would have accepted cone 6 oxidation as an option, because I was taught that serious potters burned fuel. I wasted tens of thousands of dollars and countless hours of my time when I opened my business due to believing that mantra. Now I say do what you want to do with the resources you have. Ig that's wood or gas or oil or electric, so be it. Just do it well.

#93674 Stoneware Bottle Cork Problem

Posted by neilestrick on 03 October 2015 - 11:42 AM

Pres mentioned glaze thickness, which can definitely be an issue with corks fitting. I make oil bottles where I leave the inside of the neck unglazed so the cork gets a good grip. If I accidentally leave it glazed, the cork will not fit properly. Glaze takes up more space then you might think.

#93643 De-Airing Pugmill Conversion

Posted by neilestrick on 02 October 2015 - 01:28 PM

The vacuum connection is likely at the top of the vacuum chamber. The clay at either end of the chamber creates the seal, and as the clay moves through the chamber the air is sucked out. It would have to be very tiny particles for the vacuum to be able to suck them up.


Large industrial pugmills, like those used by the clay body manufacturers, have two augers- one upper that moves the clay into the vacuum chamber, and one lower that moves the clay out of the vacuum chamber and extrudes it out the end nozzle. As the clay enters the chamber it goes through a screen of sorts that cuts it into pellets so the vacuum can really penetrate into the clay and get all the air out. For those, the vacuum pump itself is as big as a Bluebird pugger. Industrial puggers are 9-10 feet long. THIS is the system I installed when I was production manager for a clay supplier. The pugger is rated for over 6000 pounds per hour.

#93601 Raw Fired Clay, Cleaning, And Food Safety

Posted by neilestrick on 01 October 2015 - 04:56 PM

At cone 10 it should be fine. I would not only glaze the inside, but also the lip on the outside. The rough clay isn't particularly comfortable on one's lips. It is possible for the unglazed surface to stain, but not easily. Those signs of use will give it character.

#93579 Re Constituting Spectrum Glaze

Posted by neilestrick on 01 October 2015 - 10:35 AM

A good basic low fire clear is 90% Frit 3124, 10% Kaolin. It's a good starting point. You can opacify it with 10% zircopax/superpax, and add stains and oxides for color. Using combinations of opaque and transparent glazes will give nice effects. If you want to brush the glaze, use the gum solution I mentioned before for 1/3-1/2 of the water when mixing the glaze. 1% VeeGum-T will also help with brushability.

#93568 Help With Oxide Colour

Posted by neilestrick on 01 October 2015 - 08:18 AM

Start with 1/4 of 1% cobalt carbonate, and test it increasing by 1/4 of 1% increments up to 1%. If it's too bright try adding red iron oxide starting at 1% and increasing in 1% increments up to 5%

#93567 Lead Glaze Recipes (No Safety Lectures Please)

Posted by neilestrick on 01 October 2015 - 08:16 AM

As far as the user of the product is concerned, the risks are pretty well zero so long as it is a well developed glaze and, in the case of lead, has no copper in it. I don't believe there is a single record of a death of someone using ceramics with a lead glaze due to lead poisoning.


We didn't give any safety lectures to the original poster. In fact, a lot of supportive responses were given. It wasn't until the post above that we got in to the potential dangers of lead use. The purpose of the forum is not just to respond to the person who starts the topic, but also to make sure that anyone who reads the topic in the future is not given false or misleading information that could be dangerous to him/herself or others. There's no way we were going to let that comment lay there untouched.

#93530 Kiln Conversion Updraft Downdraft Chimney?

Posted by neilestrick on 30 September 2015 - 02:59 PM

In a kiln that small a downdraft would do wonders to help even out the temperatures. I'm sure you've seen all the threads here on the forum about the troubles people have keeping the round updraft kilns even.


You biggest problem will be getting the stack to fit tight with the wall of the kiln. Any gaps will affect the draft. I would think about cutting away part of the steel jacket on the kiln and weaving the chimney bricks into the wall bricks at the flue opening or at the very least having the chimney bricks fit inside the wall bricks, not just butted up against the outer surface. The chimney could run horizontal for a brick or more before going vertical, so the chimney can be framed/stabilized independent of the kiln body. It won't be portable, of course, but you want to get the tightest fit possible so as not to spoil the draft.

#93403 Different Frits ... How Important Is It To Have The Right One?

Posted by neilestrick on 29 September 2015 - 08:21 AM

If you plan on doing a lot of glaze testing, you'll want to have 3110, 3124, 3134 and maybe 3195 in your arsenal.

#93328 Maiden Bisque Witness Cone 05 06 07 Melted To Washed Shelf

Posted by neilestrick on 28 September 2015 - 09:32 AM

Someone else's firing schedule will only work for the turn-up schedule of the firing. How long it takes to get to temperature will depend entirely on your kiln. a small kiln will typically get to temp much faster than a large kiln. It may hit temp only an hour after turning everything up to 'high', or it may take 4 hours or more. You have to watch the cones or use the sitter to turn it off at the correct time.


If the cone support bars will sit snugly in the sitter tube, then it is probably useable. Post pictures if you can.

#93326 Potters And Pets

Posted by neilestrick on 28 September 2015 - 09:28 AM

I love all my pets (3 dogs, 1 cat, 2 fish), but yesterday one of the dogs spent the day barfing around the house, which made it difficult to love him. :D

#93227 Lead Glaze Recipes (No Safety Lectures Please)

Posted by neilestrick on 25 September 2015 - 01:12 PM

As far as the user of the product is concerned, the risks are pretty well zero so long as it is a well developed glaze and, in the case of lead, has no copper in it. I don't believe there is a single record of a death of someone using ceramics with a lead glaze due to lead poisoning.


The risks of eating from lead based glazes are real. Just because something doesn't kill you doesn't mean it's not bad for you. There are numerous health concerns from lead exposure. For instance, children suffer all sort of developmental problems from lead.


Here in the US:

  • Dishware leaching lead above 3 ug/mL of lead is banned under FDA rules.
  • Dishware leaching lead between 0.226 ppm and 3 ug/mL of lead can be sold in California only with a warning label.
  • Dishware leaching less than 0.226 ppm of lead may be labeled “lead safe.”
  • Dishware should be labeled “lead free” only if it does not contain lead.

If you plan to sell functional works that contain lead, you need to get them tested first. For decorative works, you should still label the piece as containing lead, because the customer deserves to know. And you better have good insurance.

#93226 Please Help: What Causes Pinholes Etc In This Cone 6 Firing Set-Up?

Posted by neilestrick on 25 September 2015 - 12:55 PM

Your best bet for the firing is to use cones in the kiln, so you know exactly how much heat work you're getting. Changing the firing schedule, application and clay body all at the same time won't tell you anything. Only change one variable at a time. Start with the clay body. Test the glaze with the same firing schedule on a white or lighter color body, and put cones in the kiln.