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A gunmetal glaze I have wanted for decades!

After 40+ years of making pottery I finally have a perfect gunmetal black. It has an incredible silky surface. It does not cutlery mark. It does not craze on anything. It is easy to clean. This is G2934Y with 6% Mason 6600 black stain firing using the PLC6DS schedule. I had to tune it a bit, adding ... more

Sunday 2nd February 2020

Why do these cone 04 and 6 clear glazes have so similar a chemistry?

The glaze on the left (as shown in my account at is a crystal clear at cone 04. The high frit content minimizes micro-bubbles. The high B2O3 melts it very well (this has 0.66 B2O3, that is three times as high as a typical cone 6 glaze). The recipe on the right is the product of a ... more

Saturday 1st February 2020

Is that recipe you found online really what you think it is?

It contains significant Frit P-25, I googled that to Digitalfire, it contains 1.8% fluorine! When that gases off during firing are you really equipped to deal with fluorine gas in your studio? One answer is to substitute my own frits (which of course do not contain fluorine). I did the calculations ... more

Saturday 1st February 2020

Red burning, customer-found terra cotta clays tested

We tested four different clays (brought in by customers). One is from BC and three from Alberta. These fired sample bars show rich color, low soluble salts and high density and strength at very low temperatures. L4233 (left): Cone 06 to 3 (bottom to top). Reaches stoneware-density at cone 02 (middle ... more

Saturday 1st February 2020

Frit Melt Fluidity Comparison - 1800F

Fired at 350F/hr to 1800F and held for 15 minutes (I already did firings from 1300F-1750F in 50 degree increments, all of them are visible in the parent project). Frit 3110, 3134, 3195, F75 have run all the way down. All of the frits have softened and melted slowly over a range of temperatures ... more

Friday 31st January 2020

Cutting out the background on a photo

White backgrounds are used for presentation on ecommerce websites (contextual backgrounds when showing a product in use). Even if you can photograph to pure white at the edges of a photo, it will transition to grey around the object and pieces will almost always have some fuzzy edges. While there ... more

Friday 31st January 2020

Adding a frit of unknown chemistry in a glaze recipe?

That is like adding a dog of unknown breed to this team. How predictable is that going to be? It is like that with ceramic glazes. They fire the way they do because of their chemistry. Not knowing the chemical makeup of a key ingredient robs you of the single biggest tool to explain characteristics or issues or propose adjustments, improvements or fixes.

Monday 27th January 2020

Sedimentary clays are a whos-who of the periodic table

These are the results of a detailed elemental composition analysis of a sedimentary clay. The first column of numbers is ppm (parts per million), divide them by 10,000 to get percent. The Fe here, for example, is 50,868 or 5.1%. The second column is +/- error. Notice that this test does not detect ... more

Friday 24th January 2020

Things that are too big to 3D print can be done in two pieces

This jigger mold shell has a step that provides the ideal place to split it into two pieces for printing. It is not necessary to do it in your 3D design app, 3D slicer software has the ability to do just before printing. In Simplify3D you just push the object downward on the platform (anything below ... more

Thursday 23rd January 2020

Cuerda seca is a flexible technique at any temperature

The mug is has an unglazed (bare porcelain) outside surface. The cuerda seca lines containing the glaze have a formulation to flux and melt more than what is typical in the classic technique on tiles. And this appears to be reduction-fired porcelain at high temperatures (because of the iron specks ... more

Thursday 23rd January 2020

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Chemistry plus physics. The on-line successor to desktop Insight. Get an account for as little as $15. It does so much more.

Conquer the Glaze Dragon With Digitalfire Reference info and software

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Interactive glaze chemistry calculations (legacy, no longer supported)

What people have said about digitalfire

• Honestly I do not see how you have time to experiment, test, etc. and disseminate the massive amount of knowledge you have.

• THANKS so much for all of the information you share at no cost. It really helps me. I feel a little guilty for not subscribing to Insight, but I am working toward that. You have truly changed the way I think about glaze, and I appreciate you. thanks. future subscriber/fledgling potter

• As I read this I am thinking wow, what a great article, so useful and I love the details of the pictures.

• As a new potter, your website has been an incredible source of information for me, both in tips, recipes and things to ponder. I know I can speak for a few others when I say please keep posting as the information is highly valued.

• I have a background in Geology (BS-1973-New Mexico Tech), and with a few other degrees here and there - and have been doing quite a bit of Pythoning, and hanging-around my wife who does (I think (but then, of COURSE I am biased)) terrific pots... I am always interested in what she does with glazes (especially when I see the mineral-names from my Geology days on the bins in her studio... BUT - as an "engineer", sometimes I want 'more' knowledge - and I find your web-site VERY VERY good at that, it tells me a lot of things - gives me 'value added' and 'information' that I haven't found elsewhere! Especially when I think about 'geo-chem'.

• So far your site has been a blessing in that I don't feel I have to go anywhere else to get my information, you have it all (at least as far as I can see now) right here in one place. I am new to glaze formulation but not to ceramics. Recently I have had a crazing problem with a certain clay body I am using and as of today I feel confident I can solve it using information on your website. It is I who want to thank you for making such a clear and concise information depository that can be used by all, especially those new to glaze chemistry.

• Thanks again for all you have done for the pottery world!!!

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What people have said about Insight-Live

• Your site is the most useful of them all for material info. and more. Thank you.

• I personally think that collaborations with the greatest expert in the sector makes me richer in knowledge and it will allow me to discover the fantastic secrets of ceramic.

• I just wanted to express my appreciation for digital fire. It's an invaluable resource that I've been using since I was 18 years old (more than a decade). Keep up the amazing work.

• You are a real gem, your work really help me a lot.

• I have been following your Site and posts continually and gained a greater understanding. Thank you for that. It is so exciting to have a positive outcome from your glazes rather then the bought glazes. ... All good and exciting. My pottery clients are excited and have recognized the difference. There is nothing better than to pass on the best work possible to those who love the pots. So much work and testing, but well worth it. Thank you so much.

• I am a big fan of your work. I want to thank you for being there when I have needed and hopefully I will be able to carry on without much input from you. I will be renewing my subsrciption soon and I extol the virtues of the program (and now the Cloud version) to everyone that will listen.

• THIS IS FRIGGIN' AMAZING! YAY! NOW I NEED GLAZE MATERIALS! WOOT! I'm blown away by your site. I'm totally going to geek out on this I can tell. Item #1 on my agenda is to stop being at everyone else's mercy for glazes.

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