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Member Since 04 Oct 2011
Offline Last Active Yesterday, 12:48 PM

#54488 Ash Glaze

Posted by neilestrick on 12 March 2014 - 09:17 AM

Regarding the traditional inconsistency of Gerstley, I heard that when Laguna bought the mine and reopened it, they mined a bazillion tons of it, ground it, and put it all in a huge warehouse where they shoveled from end to end with dump loaders until it was all uniform. Thus, they now have many years supply of a consistent product. The analysis is slightly different (and published on their website) than before, but it is now a known quantity and reliable product. If anyone has heard differently, please advise.


Yes, the current supply is supposed to be pretty consistent. We've had a lot of conversations here about Gerstley, some quite heated. I started using Gillespie when it came out and just kept with it.

#54403 How Can I Add A Metal Rod Or Pipe To A Ceramic Sculpture After It Is Fired

Posted by neilestrick on 11 March 2014 - 03:27 PM

Shrinkage will depend on your clay. Stoneware, about 12%. Porcelain, 14-16%. Earthenware, 6-8%.


As for your large sculptures, I would spend some time in the plumbing section of the hardware store. There are dozens of fittings that can be used for screwing pipe together at many angles. The main difficulty with using pipe is getting the pipe threaded to work with the fittings.


You could also use tube steel with slip-on fittings, although they are more expensive than regular black pipe fittings. HERE are some other possibilities. Welding is always a good option, too. You can pick up a little flux core wire feed welder that runs on 120 volts for $200- $250 that is quite simple to use.

#54171 Glaze Test Ga28-A Green Breaking Blue

Posted by neilestrick on 08 March 2014 - 09:59 AM

What charts are these? I have no charts that tell me things like this  :mellow:


Beautiful glaze, would love to see one of your mugs with it on.


Glaze formula limit charts. They show the acceptable limits for each part of a glaze in the unity formula. If the numbers are within the limits, then a glaze is more likely to perform well. There are, of course, perfectly good glazes that have numbers outside these limits, but they are a good place to start, and can show you where to make adjustments if the glaze is having problems.



#54116 How Can I Add A Metal Rod Or Pipe To A Ceramic Sculpture After It Is Fired

Posted by neilestrick on 07 March 2014 - 02:16 PM

Epoxy is your friend.

#53937 What To Do With Hairline Cracks While Clay Is Drying

Posted by neilestrick on 05 March 2014 - 10:54 AM

I throw it away and make another one. For me it's not worth the time trying to fix it knowing it may just come back in the bisque or glaze firing.

#53704 Glaze Waste Hazards

Posted by neilestrick on 01 March 2014 - 09:22 AM

When I worked as a tech for a clay and glaze supplier, we once had to get rid of a bag of barium carb for some reason I don't remember, and the local and state laws all said there wasn't enough of it to matter, and it was close to a full 50 pound bag. So into the dumpster it went. Like John said, chances are any of the heavy metals that would cause concern probably don't exist in large enough volume in your studio to matter. Should we still do things like fire them into a glass before disposing of them? You bet. We should do what we can to make the world a safer place.

#53568 Fritted Vs Free Borax In Clay Body?

Posted by neilestrick on 27 February 2014 - 02:14 PM

With regards to plasticity Neil, I find no problems with up to 30% frit, so I'm hoping the same for the glass powder. The tiny bit I made up this morning didn't feel any different than it normally does with the frit.

Oh and there's not a snowflake's chance in hell of me even entertaining the notion of making my own frit!!! I'm super impressed at Tyler making his own, but even the thought of it terrifies me!!


I meant the soluble borax affecting plasticity, not the frit. I was unclear there.

#53485 Making Your Own Glaze

Posted by neilestrick on 26 February 2014 - 01:31 PM


I have been making my own glaze for a little over a year now.  I am no expert, but have had good instruction.  It takes hours and hours of testing and firing.  Here is a video that I made following the way several potters that I know as well as some noted potters on you tube, Hsin-Chin Lin, and Simon Leach mix their glazes.




Here is another thing that I learned recently that others may already know.



Perhaps this tip helps.


In your first video I'm not quite sure about why you are dry mixing the glaze ingredients prior to adding water. You are making a lot of dust unnessasarily, the silica dust will stay airborne for hours. It's not just the dust you can see thats a problem, there will be fine dust floating around for a day or so. Your jiffy mixer and sieving twice will disperse all the ingredients well without dry mixing. (I put the clay component in the bucket first then the heavy settlers after that then wet mix and sieve)



I agree. I always put the clay into the bucket of water first, then everything else. Keeps the dust way down. You will have to dry mix the bentonite with one of the other ingredients, probably the kaolin.

#53464 Fritted Vs Free Borax In Clay Body?

Posted by neilestrick on 26 February 2014 - 10:28 AM

Borax is soluble, which is why we don't generally use it in glazes. You want the glaze materials on top of the clay, not absorbed into it. This is why we use frits instead- they have already fused the boron into a non-soluble form. If you were to use it in a clay body, you would probably lose some of it during the throwing process and throw the formula out of whack.


It would be worth trying the recycled glass powder. If it melts at a low enough temperature it may not matter if it's a boron base or not. Do you know the melting point of the glass?

#53309 Underglaze Issue

Posted by neilestrick on 24 February 2014 - 05:16 PM

The stage at which the underglazes are applied should not have any effect on whether they run with the glaze. The glaze can pick up the color and run with it whether it was bisqued on first or not.

#53119 Making clay 101

Posted by neilestrick on 21 February 2014 - 07:56 PM

Neil are you suggesting replacing all or part of ball clay.

"A popular buff firing plastic Missouri fireclay of fine particle size. It fires a light color with approximately 10% shrinkage at cone 10. Ground to 35"-- digital fire.com

I think I have Hawthorne 40 mesh. Which would be even smaller particle size. Nonetheless it feels better. Yet to se how it performs under wood fire. But I trust the source dick lehman.

I do have some sagger xx. Not sure on particle size. S Would this work as well and it's known to flash well.

Never considere particle size in formulating clays? Is it better to include wide range of particle sizes?

What is your concern with silca in body?

When you say flint I assume that is silica?


Good particle size distribution gives you more workable clay. Large particles with smaller particles in between them, and even smaller particles in between those, etc, and a thin coating of water around everything. Everything sticks together very well.


No concern about the silica (flint) in the body. When you originally said that it had 25% neph sye, then I assumed it also had about that much silica for it to act on, which meant the clay content would be low, like a porcelain body.


I love fireclay, much more than ball clay. I'm not saying you necessarily need to replace the ball clay, but if you put in some fireclay, something else needs to come out. You could just add in 15% fireclay and take half from the ball clay and half from the kaolin. It would probably be a pretty nice body then. Hawthorne is nice stuff. All fireclays are in my opinion! They all feel a little different from each other, though, and some give larger iron spots than others.


XX Sagger is used a lot in white stoneware bodies if I remember right, since it's lighter in color in it's raw form than other ball clays,and for some reason everyone wants their white stoneware bodies to be white before they're fired, too. From a plasticity standpoint, my favorite ball clay is C&C from HC Spinks. I don't think that at 14% you're going to see a big difference in fired color  from one ball clay to another, but you might notice it in the throwing.

#53114 A Few Glaze Problems, Drying To Slow... Not Enough Suspension.

Posted by neilestrick on 21 February 2014 - 07:41 PM

Add 2-3% bentonite and 0.5-1% epsom salts.

#53041 I'm A Glass Worker Buying A Ceramics/glass Kiln, And I Have A Q About Por...

Posted by neilestrick on 21 February 2014 - 08:08 AM

You can use a cone 6 porcelain, which will vitrify at 2232F. It's better for the kiln if you only fire to cone 6. The elements will last twice as long as if you fire to cone 10. Personally, I'm not a big fan of lid elements. They sag and fall out and require a lot of maintenance, especially when you start firing at the higher temperatures needed for clay work. However the kiln with the lid elements has a better controller. The 3 button controller on the other kiln is not nearly as user friendly, and may not have all the features, either. Check out the little L&L, Olympic and Skutt test kilns, too. They have the Bartlett V6-CF controller which is the most user friendly.

#52965 Making Your Own Glaze

Posted by neilestrick on 20 February 2014 - 11:03 AM

I'd love to have you in the summer class! Here's a PDF with the materials that I keep in my studio. Start by just buying whatever materials you need for the glazes you want to make, and add as you go. You can make a lot of really nice glazes with just:


Custer Feldspar

Nepheline Syenite



Frit 3134

Gillespie Borate




These materials make up the bulk of the 15 glazes we use in my studio. Then you just need metallic oxides or stains for color.


Find 3 glaze recipes you really like- a gloss, a satin and a matte- and make 2 or 3 colors of each and you'll be set. Make sure you have a good mix of transparent and opaque glazes.


Attached File  Estrick Glaze Materials.pdf   60.48KB   96 downloads

#52955 Your Labour Cost?

Posted by neilestrick on 20 February 2014 - 09:42 AM

I get $75 per hour for kiln repair labor, and I use that rate for other professional services outside the studio when appropriate. I have no idea what I make per hour from pots. It doesn't really matter to me, it's more of a bottom line thing. Plus i rarely get to sit at the wheel for any extended period of time, and it would depend greatly on what type of pots I'm making. Little cups have a radically different labor cost than big jars.


We've had a lot of discussions here on the forum about setting prices for our work, and inevitably someone puts forth a mathematical formula for calculating the retail price of their pots. I don't think that works, because with all other things being equal, someone who makes pots faster shouldn't necessarily charge less for their pots. And will you lower your prices as your speed increases? And all things being equal, what if one person makes great pots and the other person makes crappy pots? Ultimately, prices are set based on what the market will bear, and you have to calculate backwards from there to see if you're able to produce the work at an acceptable cost to be profitable.


It's less depressing to not calculate your hourly wage. We do this because we love it, not because of the money.