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Member Since 04 Oct 2011
Offline Last Active Yesterday, 10:49 PM

#117052 Stoneware Limit Study

Posted by neilestrick on 24 November 2016 - 10:05 AM

I got that out of the WOPL test hey?  Thinking next spring I might actually have a "theorem" on formulation. Got these ideas rolling around in my head, but there is nothing subjective out there to rationalize or compare to. Maybe I should email the WOPL test to Tony Hansen: nothing on his site either. It would be nice to be a trail blazer, only problem; there are no trails out here.





#117026 Why Are Some Glazes Nicer To Deal With?

Posted by neilestrick on 23 November 2016 - 10:42 PM

I see a lot of glaze recipes that are low in clay content, and they tend to be powdery when dry on the pot. I always shoot for at least 10% clay in my glaze recipes. I've got some that are closer to 20% clay, and they are super easy to handle.

#116920 Help ! I Can't Center

Posted by neilestrick on 22 November 2016 - 03:10 PM

I'm very deep. :P  I just mean that it's not all about wobbles, it's about the condition of the clay- getting to be a smooth, even, homogenous mass, which coning does very well. It's easier to live with a little wobble than with an uneven ball of clay.

#116860 018 Firing With Oxides Second Firing At Cone 6

Posted by neilestrick on 21 November 2016 - 04:44 PM

Hard to say, and depends on the clear. Just putting a clear on it at any temp is going to change the color vs the raw oxide. For a watercolor effect, watered down underglazes work very well.

#116833 Cone 2-3 Poll

Posted by neilestrick on 21 November 2016 - 12:29 PM

Cone 3 crystalline would be mind blowing. Imagine doing long holds and not frying your elements.

#116799 Cone 2-3 Poll

Posted by neilestrick on 21 November 2016 - 12:24 AM

I get 150-160 firings out of my elements as a combination of bisque and cone 6- about 35% bisque, 65% glaze. I get about 25% greater element life than I did at cone 8. I've know people who get several hundred firings using their kiln for only bisque. So at cone 2 I think we could realistically see 225 firings (combined) or even more. I've got 1100+ firings on one of my kilns so far, and I don't see why it wouldn't go 2500 firings (probably a lot more) before it's dead. Over that lifespan that's 5.5 fewer element changes. At $312 per element change that's $1700 saved in element changes over the life of the kiln. In my big kiln, at $730 per element change, that's over $4000 over the life of the kiln. Put those together and I can buy a couple of new kilns! Add in thermocouple life and the savings are even greater. You'll also get great thermocouple accuracy at cone 2. I also think that relay life would be a little better too, because there's less heat from the kiln to burn them out. Over all kiln life would also be increased.


If I save just $2 per firing by firing cone 2 rather than cone 6, that's $5000 over the life of the kiln (that's 2 more new kilns!), or enough to pay for a set of elements each year. And I honestly think the firing cost saving could be more than that for 28" wide kilns. There's a big increase in power draw to get from cone 2 to cone 6. In my big kiln, which is $35-40 per firing, I could probably save $10 per firing. At 75 firings per year that's $750 dollars per year in lower firing costs. That's a set of elements.


As for the cost of clay, if the cost of the clay goes up 25 cents per pound (that's a lot) in order to get it down to cone 2, then I would have to add 35 cents to the price of every mug, a dollar to some larger things like pitchers, to cover the increase. The majority of what I sell is under 3.5 pounds. Done. Easy. Clay is cheap in the big picture. I already use a lot of frits in my glazes, so I don't think the glaze costs would increase enough to matter. Maybe a couple of cents per pot. If I just add $1 to every pot I sell I would come out ahead.


On top of all that, we'll be using less energy, which is a big deal nowadays. I can see why someone like Mark, who has built their career on cone 10 reduction, wouldn't want to switch. He doesn't have a good reason to. That would be a drastic change. But for anyone working at cone 5/6 it would make a lot of sense.

#116704 What Am I Forgetting?

Posted by neilestrick on 19 November 2016 - 03:36 PM


#116696 Found A Cord, What Kind?

Posted by neilestrick on 19 November 2016 - 01:41 PM

Toss it. The insulation is probably getting brittle.


Most kilns use a 3 prong cord- 2 hots and a ground- where each section of the kiln runs on 240 volts. Some old kilns and new smaller kilns use a 4 prong system- 2 hots, a neutral, and a ground- where each section runs on 120 volts.

#116635 Hooray! It's Over!

Posted by neilestrick on 18 November 2016 - 04:48 PM


#116619 Stoneware Glaze Unexpectedly Crazing :(

Posted by neilestrick on 18 November 2016 - 11:10 AM

The lithium will have a big effect on the COE of the glaze.

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#116436 What Happens When A Relay Fails?

Posted by neilestrick on 15 November 2016 - 10:10 PM

Correct. When a relay fails 'On', shutting off the power to the controller will not affect the relay at all. The mechanical contacts are welded together, and no signal (or loss of signal) from the controller can make them move. In my experience, only about 20% of relays fail 'On'. The rest fail off in one of 3 ways-

1. It totally stops working, but shows no physical signs of it being dead. This is the most common scenario. You have to use a meter to figure it out.

2. It stops working and totally fries out and melts part of the outer casing. This makes it easy to tell which relay is dead. It's kinda cool to see.

3. It sticks. When the controller sends out a signal it sometimes works and sometimes doesn't. This is a pain to diagnose, because it most often happens at high kiln temps when the controller is heated up. Usually when they get sticky they'll totally fail within a few firings. You have to do a program with a rate of 9999 and turn it on and off several times to try and get it to stick.


Here's what I have seen: When a relay fails 'On' in a 3 ring kiln, you may get some slight over firing in that particular section of the kiln at low fire temps. When firing to cone 5/6, that one section should not overfire, but rather just slow down the cooling of the kiln as a whole. In a 2 ring kiln firing to low fire temps, that section of the kiln can definitely overfire when going to low fire temps. I don't know what will happen in a 2 ring kiln at cone 5/6. Haven't seen it. 95% of the kilns I work on are 3 rings.


The odds of more than one relay failing 'On' at the same time are pretty slim. Like probably lottery odds slim. But it is possible in theory. This is why you should always check to make sure the kiln has shut of properly. The controller can't stop a fused relay.


If a relay sticks, the controller will know it and will put up an error code and stop the firing. I think you can use Output 4 on the controller to power a large main relay that feeds the other relays, so when the firing shuts down the main relay will kill power to the others. I would confirm that with Bartlett before trying it. Of course, in theory the main relay and the smaller relays could all fuse 'On'.....

#116401 Finding Environmentally Safe Glazes

Posted by neilestrick on 15 November 2016 - 03:57 PM

Well, that's an overreaction, and kind of ridiculous if they use electricity in the school produced by anything other than solar or wind power. The amount of metals released into the air by the coal burning power plant during the production of electricity to run the kiln is probably more hazardous than the metals that might get into the waste stream from glazing pots. I get their point, but come on already. Glazes with  those materials can be certified non toxic, meaning you can ingest them without dying, so by the time they get into the environment they would be so diluted as to be a non-issue.


Have you talked to them about ways to minimize the glazes getting into the waste stream? For instance, instead of using the sink you can use buckets of water to rinse brushes and sponges, and when the glaze materials settle out in the water they can be collected and fired into glass that can be safely disposed of. Or you can take all that glaze material and add some kaolin to it to stiffen it up and actually use it on non-functional work. The amount of glaze that would get into the environment would be tiny.


Which metals, specifically, are banned?

#116396 Clear Glaze Changing The Color Of Glaze/clay Body Below?

Posted by neilestrick on 15 November 2016 - 02:22 PM

Looks to me like it's picking up some cobalt from the engobe.

#116353 Glaze Ingredients Req'd To Bring Out Effect Of Iron In A Clay Body?

Posted by neilestrick on 15 November 2016 - 08:53 AM

That's just a fancy way of saying the glaze will look different on a darker clay than on a whiter clay. All glazes do that for the most part, some more dramatic than others. Looks like your basic oatmeal spodumene glaze. I don't know that there's anything specific you can add to a glaze to make it happen, though. It's just the nature of the glaze.

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#116282 So Close ... But Not ...

Posted by neilestrick on 14 November 2016 - 11:46 AM

I always tell my customers I can get to within 1/4 inch. Too many variables at play to guarantee anything closer. You're brave for even trying!