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  1. Perfect! Thanks so much for the great explanation The person who bought my mugs said (even though I had said he may not want to microwave these mugs again) he did microwave in them several times and after the couple of "tinks" the first time, there has been none since, and no crazing (I told him how to check)! So, he knows to be watchful, but I'm pleased that they seem to be ok *so far*. He said he is happy to update me to let me know longterm. Thanks so much everyone!
  2. Thanks again! I think I'm getting it.. Yes! I will make a test cylinder and craze test these glazes. I've tested many of them with pots that I keep, but not this combination. One thing I'm still wondering about is the lower COE of the Assad having less chance of crazing..i thought that the COE should be close to the COE of the the clay body. Or is it just lower COE means less crazing in general? I do understand that these 2 glazes inside vs outside would cause stresses. Lorraine
  3. Hi, so I looked up the calculated expansion of the liner glaze in this set of mugs, and from Insight Live = Assad Opalescent = 5.7 The Tuckers 6-50 clay appears to have an COE of 7.71 So, I am still learning (and enjoying this!) but I understand that the calculated expansion values are not necessarily predictive for risk of crazing (or shivering) BUT these two are quite extremely different, especially compared to some of the other glaze recipes I use. For example, the Floating Blue #2 Has a COE of 7.8, and the liner clear I usually use, Hansen's 20x5, is 7.0 . So, am I right in thinking: the Assad is not the best choice of recipe for this clay based on the COE? That the Assad, as a liner, may be starting to craze in these mugs, causing the pings in the microwave? And, is it theoretically possible, that the crazing of *any* 'at risk' glaze occurs more frequently if the pot/mug is heated too quickly/ to high heat vs slow heating ? Thanks again, Lorraine.
  4. Thanks for the information! I guess I have made the assumption that if the inside of a mug has a safe "liner" glaze, the fact that the more questionable Floating Blue #2 glaze is only on the exterior/ no food contact that it should be okay. I did test these glazes in to microwave before, just not this specific combo of glazes together. That's aside from the glaze fit- COE issue that I'll be trying to figure out. I will change my microwave safe claim. Was too bold in thinking since none of my pots has issues for me so far that it was safe to proclaim : not! Thanks again!
  5. Hello! This is my first post after reading so much fabulous and useful advice on these forums the last couple of years. I'm still a bit of a newbie potter and I've been selling for just over a year. So far I've been really pleased and no complaints or negative comments (exception: why don't you make in blue?) LOL. So I sent off a pair of mugs (Etsy sale) and the new owner is really happy with them, except that he just tried to microwave one to reheat his beverage, and he heard some "pinging" noises. He was alarmed and took the mug out and didn't try again; he's just wondering if I know what is going on. The details: I use Tuckers Pottery 6-50 cone 6 porcelain clay. I fire to cone 6 based on witness cones. (I use cone 7 in the kiln sitter to get there). Glaze: I am making my own glazes. The liner glaze in these mugs was an Assad Opalescent (basic high percentage frit based glaze with no added oxides). Outside was a floating blue glaze (from John Britt's book of Cone 6 glazes: Floating Blue #2) I've used both of these before and have been very happy, and I've personally have had no problems with anything in my home. Unfortunately, I have sold everything at this moment that has this exact glaze combo. Also not sure if a mug done the same isn't necessarily going to be a perfect "test" as glaze thicknesses, exact kiln position, exact top temp, etc may be slightly different? Any advice would be really appreciated! Mostly I'd like to know if in *your* opinion I should tell this buyer not to try to nuke these mugs? I know I've been a bit "reckless" in claiming my things are microwave safe and I'm sorry now I did without being more sure. I've read the forums about the astm standards and I plan to at least test more carefully than just a few things I have at home. Thanks in advance! Cheers, Lorraine.
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