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simatai33 posted a topic in Clay and Glaze ChemistryHello everyone! I am stumped on this issue and was wondering if anyone had any insight or advice on this. We opened our soda kiln a couple weeks ago and I had a problem with my work. I fired 64 pcs, most of which was Rods Bod clay body which also had some Red Iron Oxide slip decoration on it. I used Penn State Shino that I mixed the day that I glazed. 60% of it had major shivering! The glaze was just crumbling off and some thicker areas coming off in large pieces, leaving a grey stony finish behind. Such a bummer! See video here: https://youtu.be/0cbd0eXvYII Some things to note in this firing: - No one else's work shivered, but no one else used Rods bod or PSS Shino. - Pieces from previous firing that didn't make it in kiln and fired this time were ALL okay. They had been sitting for 6 wks and were Rods Bod with RIO decoration and PSS glaze. - I fired over two dozen spoons with Takamori clay body and PSS glaze, and NONE of them shivered. There was some crazing. - All my Rods Bod pcs with SF Shino or other glazes did not shiver. - 5 sake cups that fired cold didn't shiver. - There was crazing on several pieces. - Areas that got hit with a lot of soda on Rods Bod/PSS would shiver. - I did rush the drying process of Rods bod, drying in the sun and did a 2 hour pre-heat when I bisqued. I never had a shivering problem with Rods Bod and PSS glaze until the last two firings, which make me wonder if it's a clay body issue, a combo of clay body and glaze fit, or something happened in the glaze mixture. Or could it be the soda ash? I did find a discrepancy in our PSS recipe vs. the one from Liz Willoughby when I double checked today; we use 4.9 OM4 amount instead of her 14.9 OM4 amt, and I wonder if that makes a difference in anything. SODA ASH SPRAY RECIPE 1 lb soda ash to 1/2 gal water PENN STATE SHINO RECIPE - LIZ WILLOUGHBY 14.6 Neph Synite 7.8 Soda ash (light) 9.7 EPK 4.9 OM4 34.0 F4 feldspar 29.0 Spodumene