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Post by alejandrob17 on Feb 5, 2019 18:38:41 GMT -6
Hi everyone, I am currently a high school senior who has developed a passion for crystalline glazes since my sophomore year. Recently I have been focusing on iridescent etchable glazes and been getting great results but I was wondering if anyone has any information on how secondary crystals form. I have read that white stoneware with porcelain slip helps aid secondary crystals formation(is that true?). Or does it rely heavily on the firing schedule? Any information will help but I also understand if people don't want to share there hard earned secrets/tips. Included are some of my favorite pieces, I would love any feedback! (If you want to see more check out my Instagram: Chunkwarepottery) drive.google.com/drive/folders/1_63KrHow9PgeOc7_9cmqNDOO8PrirD55?usp=sharing-Alejandro |
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gczop
Full Member
Posts: 202
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Post by gczop on Feb 7, 2019 9:58:39 GMT -6
Welcome Alejandro, A 3110 base with 2% each of TiO2, MnO2 and CoCO3 may produce secondaries, cone ten. Glaze thickness (thinness) matters. "Black snowflake", orange (titanate?) and cobalt colored willemite below on the same piece.
Cheers, Gordon Also see microcrystals threads by Evan for ideas.  "black snowflake"  |
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Post by bill2015 on Feb 8, 2019 8:43:58 GMT -6
I have found with my glazes the use of nickel seems to enhance the creation of secondary crystals more than other colorants.
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Post by evan cornish-keefe on Feb 11, 2019 1:06:01 GMT -6
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Post by evan cornish-keefe on Feb 11, 2019 21:08:26 GMT -6
Hey again, I recieved a message about the link not working, it appears to work for me so if there's an issue let me know. The article is from page 186-198 by Ray Stull, maybe the issue was that it takes a while to load the full publication? Curious to know what folks think, as i found it very insightful. Also Alejandro, realizing you're in high school, I wouldn't have had any idea what an "RO" was when I was a senior. So a brief overview, and folks please correct me if I botch this: "R" is a place holder, since no elements of the periodic table are labeled "R" to confuse it with. R2O, aka Primary Fluxes or Alkali Metals, are Li2O, Na2O, K2O RO, aka Secondary Fluxes or Alkaline Earths, are MgO, CaO, SrO, BaO, and ZnO I'd say colorants can also be considered an RO, as they often act like a secondary flux and tend to crystallize. CuO CoO MnO NiO FeO, although they are often considered seperately from the base glaze too. In the Unity Molecular Formula, the total R2O plus RO will be equated to 1, and other materials will be in relation to that (the sum of the fluxes). RO2, or glass former, SiO2 R2O3, or glass modifier, Al2O3 is a stabilizer, and B2O3 is a glass former and flux. Ray Stull developed a map showing the effects of silica and alumina with the fluxes being constant, which is remarkably consistent. Most crystalline glazes fall in the far lower left area of this map, where glazes are fluid and crazed. This link may be of interest too: www.youtube.com/watch?v=7-h6GlJrDDkJust to show the wide range of possibilities here, you could use Titanium and get glittery yellow Rutile crystals in the background, or blue rivulets of Calcium Borate (or other colloidal crystals), or go in the direction of Barium Matte crystalline glazes.... My observation has been that one type of crystal tends to predominate, stunting the growth of others, not to say I havent seen glazes that develop three and more crystal structures simultaneously, but that gets to be a very delicate balance of temperatures and glaze thickness, as much as chemistry. |
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Post by alejandrob17 on Feb 14, 2019 23:21:05 GMT -6
Thanks so much, I will definitely take a look at all the information you shared! I will keep this forum updated with my future new work. In the coming months, my school allows seniors to partake in an independent senior project that lasts over a month and for mine, I will be focusing my entire time on creating more crystalline glazes and new pieces.
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