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Matt Katz

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Everything posted by Matt Katz

  1. Thanks Neil. It is a possibility that the body has some porosity, Although the maker is extremely experienced, and I trust them when say say the body is well fired (although I haven't run absorption numbers on it). As the issue is really water/residue remaining behind if it is in the body or the crazes, does not seem like it makes a difference, to me. As trapped water is trapped water.
  2. Hi All, I've just posted my newest video about what really causes crazing, what are the issues with crazing and some solutions for avoiding it in the long term. I hope you like it! [Video removed by moderators, due to its advertising content. You can visit Matt's website to view the video.]
  3. Hi Jospeh, Have you ever glazed work before? Great, the class is for you. I've taught students with one class and masters with 50 years of experience. All love the class. As to details. I am comprehensive and detailed. I've spent 20 years working in ceramic science, but I have a BFA and MFA. So I understand the needs of the artist and the knowledge of the scientists. i don't leave anything off the table. This is the same class I've been teaching at Alfred for 15 years, all facts, no rumors or myths. You'll love it.
  4. You're all linking to the same guy... and I'm that guy! Seriously though, if you have any questions feel free to ask. (I'll try to remember to check back) For those that don't know me. I been teaching glaze calc at Alfred for 15 years, and I've been teaching an academic version of my class, online for three years. Starting July 1st, we will be offering our first version of the class for the general public. You can find out more information, and sign up here http://www.ceramicmaterialsworkshop.com/glaze-calculation.html Best, Matt
  5. Hi Everybody, We're back with another online materials video, How to Calculate the Unity Molecular Formula. If you like these video's please follow us on Facebook! https://www.facebook.com/ceramicmaterialsworkshop/ and visit our website for more on-demand, online workshops http://www.ceramicmaterialsworkshop.com/
  6. Thanks Martin! That is very nice of you, We love teaching about materials and helping everyone make their studios better. There is plenty more to come! Keep your eyes on the skies (and our Facebook group https://www.facebook.com/ceramicmaterialsworkshop/ ) And please spread the world, tell all your friends and social networks about us. Word of mouth is the best adv ertising in the ceramics community.
  7. Have you ever wanted to learn Glaze Calculation or Clay Science, but haven't had the opportunity? Alfred University is now offering our world renowned classes in clays and glazes online to everyone! Following in the footsteps of Val Cushing and Daniel Rhodes, I have spent over 15 years crafting a new version of our clay and glaze classes. Wherein I take the best research from Alfred's school of ceramic engineering and translate it for artists of all levels. They are the perfect courses if you want answers to those burning questions, If you teach these subject and need a refresher, or are a beginner and want to understand what is going on in your materials. The next session of both classes will be starting December 14th and run until January 15th. You can take the courses for academic credit. Or if you are a life long learner, you can audit the course for half the list price. See the attached pamphlet for some of our incredible reviews and more information. Or visit our website. http://art.alfred.edu/academics/glaze-formulation.cfm
  8. No, The substitution is more complicated than that. I would have to say that you need to look for a new batch of formulas. Your old formula is basically ^6 and you kiln is fining under ^04.
  9. wire stilts is your best bet
  10. Glazes require 5-10% clay for suspension. That would alter your formula substantially. try 1-2 % bentonite as an alternative.
  11. Marcia I learned something new a couple of weeks ago, I went to a lecture on glass as part of the Kansas State University open house, the professor giving it said glass is technically a liquid but it never flows. He said it was an old wives tail that old window panes got thicker at the bottom, the process of making glass in the past would leave one side thicker than the others and they would install that side at the bottom for more strength. He said he believed the old wives tale until he started studying glass, he does the glass blowing for the university from extremely fine tube to huge Frankenstein glass assemblages. Denice This is correct. Glass exists in a state called a "Super Cooled Liquid" meaning that it is still in liquid form, but does not flow at room temperature. For glass to flow in the idea of the old wives tale, they would need either substantial heat or geologic time. As to the previous question and to clarify Marcia, Glaze is glass, they are one in the same. The major differences is that A) Raw glaze is in the material state having never been melted and is generally composed of Flux (feldspar and Carbonate) Flint (silica) and Clay. The glass that she is referring to is not true unless the formula contains a frit, which is a glaze that has been fully melted and ground into a powder. B ) We add Alumina for stiffness which most traditional glasses excludes because they want to have their molten glass to have a lower viscosity (Flow more) where as if our glazes flowed in the molten state, they would run right off the piece.
  12. There is no such thing as "too slow for Strontium." Strontium is an Alkaline Earth Flux just like Magnesium, Calcium, and Barium (and Lead and Zinc). It does not have any particular behavioral trend that the other Fluxes don't. Glazes that are properly formed mattes will be matte independent of cooling cycle. The same with gloss. Let your kiln cool naturally and if the results are pleasing to you then, there you go. If it is a matte glaze you can influence the density of the crystal growth in the matte (properly formed matte glazes are crystal that grow in a gloss base). You can increase crystal growth by cooling slowly (or firing down) through the beginning stages of the cool down. But as the growth cycle depends on the viscosity of the glass it doesn't last for too long. once the glaze solidifies, it isn't going to crystallize.
  13. "Crackle" is actually a glaze defect called "Crazing". Crazing occurs when there is a fit mismatch between the Glaze and the Clay. Because of this it depends, on the clay as well.
  14. Excellent post John, I would just like to add to the community that, the fact is that people are going to do whatever they want in their studios. Because of this, we as a community need to aid each other in doing things as safely as possible. We are never going to dissuade anyone from something they deem important because of potential dangers. If safety was our only concern, none of us would ever get into a car. So let's pledge to help each other as best we can.
  15. Ok Everyone, Nothing has gone overboard yet, but I see tensions brewing. We would like to keep this forum neutral and scientific. If you make a claim, please avoid opinions and supply data to back up your statements. We are all relying on the expertise of each other to advance the discourse.
  16. not true, read my previous posts in this thread. yes, i did. but are there not many reasons for why pinholing may occur? there are a few, but gas escape is only possible in once fire, never in bisque ware.
  17. not true, read my previous posts in this thread.
  18. Yep, Just don't add colorants. Should work with just about any crystalline formula.
  19. It is impossible to know without confirming with the source of the data. Absorption is very important. Ideally you want absorption as close to 0.5% as possible (basically within the margin of error of 0%)
  20. I can't quite figure out what is going on. The rest of the person's post seem legit...
  21. Correct, explosions are always caused by moisture.
  22. Freezing is not an issue. Freezing of the water is not going to change the particles inside the clay. It may redistribute the moisture in the clay when it thaws. As Jim said, wedge it and keep making.
  23. Materials pack themselves based on a variety of factors. Each of the materials has a different size and shape and when mixed into a suspension they distribute themselves (hopefully homogeneously). We refer to it as the Room full of Balls; Fill a room with Beach balls and you can fit soft balls in the empty space between the beach balls. Golf balls in between the space in the soft balls, etc. , Different materials (ie excessive clay content) cause materials to pack inefficiently, leaving large void spacing between the materials. As the glaze melts, void space air is trapped by glass. Which become pinholes and the bubbles we often see inside glazes. The simple proof that bubbles cannot be a result of "Gas release" is ask yourself the question. "Do you see pinholes on the bottom of plates and bowls?" Of course the answer is yes, with the problem being that gases (at least the ones generated in a firing) rise. And this is also accentuation with the viscosity of glass pressure of bubbles problem mentioned earlier. Biqsue temperature should have no effect. The bubbles you are indicating are much larger then the void spacing that I am referring to. They need attention but are not the same problem.
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