glazenerd Posted July 26, 2016 Report Share Posted July 26, 2016 I have been working for several years trying to formulate a clay body for tile work, but even more so conducive to crystalline glaze. The criteria being: 1. Stayed flat when forming. Once I cut it, I do not touch it again until bisque. No flipping, no weighting, etc. DONE! 2. Raise the COE to get closer to crystalline glaze. (not there, but much closer.) Use to get elongated concentric linear cracks. 3. Formulate to encourage crystal growth. DONE! The top tile is iron fired to cone 10 with a total 2.5 hours of soak. (1 5/8" max. crystal size) The bottom tile is copper fired to cone 6 with 2.5 hours of soak. ( 2 1/4 " max. crystal size) Cone 10 is used by most potters firing this glaze because it produces larger crystals: that is no longer the case. Nerd Note: all crystalline glaze has a crackle effect COE, nature of the beast. Link to comment Share on other sites More sharing options...
Joseph Fireborn Posted July 26, 2016 Report Share Posted July 26, 2016 Congratulations. Break those bonds. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted July 26, 2016 Report Share Posted July 26, 2016 Beautiful examples. Glad your perseverance is paying off. Well done! Marcia Link to comment Share on other sites More sharing options...
Pugaboo Posted July 26, 2016 Report Share Posted July 26, 2016 Gorgeous! You are achieving wonderful things. They look almost organic like flowers or something. Simply beautiful. T Link to comment Share on other sites More sharing options...
glazenerd Posted July 26, 2016 Author Report Share Posted July 26, 2016 Actually Pug, I call the crystals "florets". we have the same eye. Marcia: I gave it the name "coma", because the clay has no memory. 0.18% MGO, 0.31 FE.. ultra white at bisque/maturity. Joseph, few more tweaks, then I am going to set my sights on bright red in oxidation. Have some ideas Nerd Link to comment Share on other sites More sharing options...
Joseph Fireborn Posted July 26, 2016 Report Share Posted July 26, 2016 I like the naming idea. Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted July 26, 2016 Report Share Posted July 26, 2016 How are you raising the COE of the body without adding soda or potassium? If I remember correct you said they are bad for crystalline glaze. Maybe it was just sodium actually. Link to comment Share on other sites More sharing options...
glazenerd Posted July 26, 2016 Author Report Share Posted July 26, 2016 Joel Sodium actually. Pearl Ash was used in part. very high COE but has to be titrated due to high PH> Some sodium in cone 10 is acceptable because the additional heat disassociates it more so. This clay and glaze each have less than 0.15% batch weight of sodium. It has been the standard that sodium is acceptable in glaze, but I have found that to be a myth for cone 6. If you look right off the tip of the lowest crystal in the iron tile you will see faint-thready crystal formations. In my testing, these are sodium crystal forming: both potassium and sodium will form crystals. Nerd Link to comment Share on other sites More sharing options...
glazenerd Posted August 14, 2016 Author Report Share Posted August 14, 2016 Tests results as of 8-14-16. After some minor tweaking of the Coma Clay formula- noted as formula T10. The large tile on bottom is Laguna Porc. ^9, and the round tile on top is Coma Clay T10. Both have identical glaze formulations and colorant percentages: both had a total of 2.5 hours of soak holds. Coma T10 peak 2228F (5m hold) Coma T10 crystal size 2.5", Laguna porc. ^9 crystal size 1.75:. Note also that the COE crazing issues have been resolved. Well, that only took 7 years to figure out. The other note of interest, critical part of crystalline glaze is application rate :Coma T10 0.40grams per Sq. Inch. Laguna porc ^9 is 0.65 grams per sq. inch. Nerd Neodymium (rare earth) Link to comment Share on other sites More sharing options...
Pugaboo Posted August 14, 2016 Report Share Posted August 14, 2016 BEAUTIFUL! Looks like bursts of golden flowers. Amazing! I'd say that was 7 years well spent. T Link to comment Share on other sites More sharing options...
jrgpots Posted August 15, 2016 Report Share Posted August 15, 2016 Marcia: I gave it the name "coma", because the clay has no memory. 0.18% MGO, 0.31 FE.. ultra white at bisque/maturity. Nerd Coma clay...........If you fired it beyond the point of vitrification ,, you call it "Coma-toast". .......just a thought. All kidding aside, it looks great. Link to comment Share on other sites More sharing options...
glazenerd Posted June 3, 2017 Author Report Share Posted June 3, 2017 Color anyone? Nerd Link to comment Share on other sites More sharing options...
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