Lapis108 Posted February 1, 2019 Report Share Posted February 1, 2019 Hi, I wondered if I could have some expert advice. I recently bought some Portuguese stoneware dinnerware from a commercial company. The plates keep pinging and small cracks keep appearing but under the glaze. They were quite expensive and I love them but don't want to keep them if this is a problem. Just some lines that don't seem to be harbours for bacteria but worried about the integrity of the plates and if this is normal! Thanks for any help. Link to comment Share on other sites More sharing options...
JohnnyK Posted February 1, 2019 Report Share Posted February 1, 2019 Under what conditions do the plates ping/ While they just sit on the shelf, while they are being used, while they are being washed? Post some pix of the plates if you can with closeups of the cracks... Link to comment Share on other sites More sharing options...
Denice Posted February 1, 2019 Report Share Posted February 1, 2019 If you can see cracks under the glaze then there are cracks in the glaze that you can't see. I would return them if you plan to eat off of them, if they are just for show you can keep them. They won't break apart just get more crazing in the glaze. Denice Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 2, 2019 Report Share Posted February 2, 2019 Very likely glaze is crazing and has cracks. If yes, this will continue and most potters do not consider them food safe. You can often verify this at its early stages with a dry erase marker. Color heavily and when lightly wiped off often reveals the micro cracks in the glaze. My opinion, return them, if crazed they likely will be more fragile as well. Link to comment Share on other sites More sharing options...
Mark C. Posted February 2, 2019 Report Share Posted February 2, 2019 Return them as they are not worth keeping-they should not ping/ talk or craze Link to comment Share on other sites More sharing options...
glazenerd Posted February 2, 2019 Report Share Posted February 2, 2019 Lapis: "Potugese >stoneware< going to give an answer for other potters as well. The pinging sound I suspect is due to cristabolite inversion: a problem more specific to >stoneware.< cristobalite inversion occurs as the pieces are cooling! not heating up. Potters who like to peek or crash cool around. 450F subject stoneware pieces to thermal shock at almost the exact temperature cristabolite formations are at their inversion range: beta to alpha. the clay body is compromised: the glaze will soon follow. Tom Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 2, 2019 Report Share Posted February 2, 2019 cristobalite not likely unless these went to cone 14 at some point. I would guess just glaze crazing Link to comment Share on other sites More sharing options...
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