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Old Mike

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  1. Leaching & Unsafe Glaze Surface

    Linnet, The testing methods I mentioned are certainly not like sending it to a lab as a later post mentioned doing. That would be expensive though and your money might be better spent in buying Mastering Cone 6 Glazes and a glazing computer program. The book would teach you what makes a stable glaze and the glaze program would let you see if you have one. On the pieces you already have that you are wondering about, I'm more curious about why they didn't come out glossy. The first two things that come to mind are a mistake in making the glaze especially if you are mixing your own from raw materials (suppliers of glazes can make a mistake on a batch too though that would be less likely or that they were underfired. Underfired would be my first choice and if that is the case you could simply refire them and make sure you reach the correct temperature to mature them. We once had a glaze that should have been gloss turn matte because when it was extended from the 100g. formula to 2000g a mistake was made in one extension and it had 40g too much Custer Feldspar in it. If it had been wonderful it might have been worth the price of testing but it wasn't so it was discarded. If a mistake was made and you can't identify it, you won't be able to reproduce it anyway. Mike
  2. Over Fired Bisque For Raku?

    I'm not sure what burnt means. If you are using a clay formulated for raku, which is usually a low fire clay, and you reached cone 8 your pots should be slumped or puddled all over your kiln. I would think that you will have a lot more difficulty getting enough glaze on the pieces to form glass and getting the smoked black on the unglazed areas than problems with cracking the pots. It is possible to refire cone 10 electric glaze fired pots in a raku kiln to reduce them so I wouldn't think firing to raku temperatures with pots already fired way past the normal firing temperature for raku would cause that big a problem with cracking. I know people who bisque to 04 for raku and then fire the glaze to a slightly lower temperature and they come out even though the clay was vitrified in the bisque. Simplest way to tell is try to fire them and see what happens. Mike
  3. Leaching & Unsafe Glaze Surface

    Linnet, A simple test would be to lay a slice of lemon on the piece overnight and see if it does anything to the glaze. That covers the acids which covers most food items. You could also run it through the dishwasher a few times and see if it fades as that would cover the bases. Mike
  4. L&l Kiln Or Skutt?

    I am the clay studio manager for a local art center. We recently got a new Skutt 1227 with 3 phase hookup. It works great. I am also familiar with L&l as we wore one out after many years of service. They are also a fine kiln. We got the Skutt because our local distributor gave us a good deal on it. For most situations the 1227 might be a little big. I have recently begun doing Macro Crystalline glazing and a good controller is an absolute must. Both kilns have one. This topic was discussed on another forum that I am on and it was about 50/50 with no one having anything bad to say about either but all have their own preferences. I plan to build a studio in my home this summer and will probably end up with an L&L as a supplier has a great package deal on a smaller L&L and the wheel that I want. My choice would be based on which one I could get the best deal on. You can't go wrong with either company. Mike