marcello Posted May 14, 2015 Report Share Posted May 14, 2015 Hello I am testing some tea dust glazes. The yellow crystals that appear on the black surface are nice, but very small in size. I saw many examples of tea dust glazes with larger crystals, and I would like to make a similar glaze. How can I do? Adjusting the chemistry of the glaze or fire it differently? many thanks Marcello Link to comment Share on other sites More sharing options...
rayaldridge Posted May 14, 2015 Report Share Posted May 14, 2015 I'm guessing it's your cooling cycle. A longer hold at the temp at which these crystals form ought to give you larger crystals, since they will have more time to form. If you're firing in reduction and using a kiln with insulating brick or fiber, you may need to fire down, since kilns of this sort tend to cool more rapidly than a traditional hard brick kiln. Link to comment Share on other sites More sharing options...
marcello Posted May 15, 2015 Author Report Share Posted May 15, 2015 I would like to attach an image to explain. How can I do? It seems like it is not possible.... Link to comment Share on other sites More sharing options...
marcello Posted May 15, 2015 Author Report Share Posted May 15, 2015 Thanks for your reply I am attaching a link to a file to explain the situation. On the right: the glaze I made. It is covered by very small yellow dots. I would like them to be larger, like the bowl on the left.... The bowl on the left comes from Japan. Looking at the color of the clay, I would not say it was fired in reduction. Do you think the cooling cycle can make the difference? Thank you again Marcello https://drive.google.com/file/d/0B1wg1x2St-AhX2J0Rno3R3VBM3c/view?usp=sharing Link to comment Share on other sites More sharing options...
rayaldridge Posted May 15, 2015 Report Share Posted May 15, 2015 Marcello, are you firing in an electric kiln? I think the difference might well be the cooling cycle. Have you tried slowing the cooling? Link to comment Share on other sites More sharing options...
marcello Posted May 15, 2015 Author Report Share Posted May 15, 2015 I will soon try. I have a propane kiln. Thank you Marcello Link to comment Share on other sites More sharing options...
rayaldridge Posted May 15, 2015 Report Share Posted May 15, 2015 Check out what John Britt says about teadust and cooling: https://books.google.com/books?id=5klq2XOXYaUC&pg=PA72&lpg=PA72&dq=glaze+iron+teadust+crystal+cooling&source=bl&ots=_Bt4-QvNcP&sig=bCNnQ0-WVq9hn15otEgFXxOaLG4&hl=en&sa=X&ei=7XNWVcOhDobGsAWFpIHIBg&ved=0CB4Q6AEwAA#v=onepage&q=glaze%20iron%20teadust%20crystal%20cooling&f=false Link to comment Share on other sites More sharing options...
marcello Posted May 15, 2015 Author Report Share Posted May 15, 2015 Thank you. I have his book, and the glaze I am testing is actually the "Coleman tea dust".... Link to comment Share on other sites More sharing options...
marcello Posted May 15, 2015 Author Report Share Posted May 15, 2015 One thing it is not clear in the book is if the slow cooling effects the number of the yellow crystals or their size. In my case the glaze as you can see is full of crystals, but they are very small. In the book the picture of Coleman tea dust (provided by the author of the glaze) looks promising but it is not one of the tea dust Britt tested. None of the tea dust tested by Britt seem to have large crystals.... However I will soon try his reduction R3 firing cycle to see how the glaze will change. Thanks Link to comment Share on other sites More sharing options...
Chantay Posted May 17, 2015 Report Share Posted May 17, 2015 Please post results. Link to comment Share on other sites More sharing options...
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