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About PaleoCeramics

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  • Location
    Thousand Oaks, California
  • Interests
    Primitive technology - ceramics, tanning, coppersmithing, etc
  1. Pinched Unglazed

  2. Seeking chemically inert glazes

    An update: I have exchanged email with Tony Hansen of DigitalFire, as well as Matt Richens (referenced on digitalfire.com) and both were friendly and busy at the same time. Wandering around digitalfire.com, one possible template is G1214W Cone 6 Transparent Base Glaze It's looking (to me) as if a first cut at the oxides goes something like this: .625 CaO .250 B2O3 .125 Na2O Along with 2.8 silica and around .35 alumina Which could be provided with (roughly) 5 parts by mass Sodium Borate Decahydrate (borax,381g/mol) 5kg = 25mol/Na 50mol/B 6 parts by mass Calcium Carbonate (Whiting, chalk,100g/mol) 6kg = 60mol/Ca 4 parts by mass Silicon Dioxide (Silica, 60g/mol) 4kg = 240mol/Si And enough kaolin to get it all to "stick". Does that sound "reasonable" to anyone out there? -Jeff
  3. Seeking chemically inert glazes

    John, Marcia: Thank you for your replies. I shall certainly purchase the "Cone 6" book you both recommended. I just want to be sure I expressed myself clearly - as a neophyte that's always a concern - I want to prevent contamination in either direction: from the container to the cargo or vice versa. Lead leaching into my preserves is bad, but so is milk leaching INTO a porous clay container - it'll never be really clean or safe to use again. Specifically, I'm looking for a simple, low-to-mid cone glaze that will let me store materials and clean the container afterwards. -Jeff
  4. When I search the in-tar-net for "glaze recipes", I find them most often sorted by texture, color, and cone. These are very important for artists, and artists are a large percentage of the people out there making pottery today. But... ceramics have a very earthy (forgive the pun) practical aspect to them as well: they make containers which are rigid, fireproof, and sealable. These are characteristics that meant a lot to early ceramic workers and their cultures. People have been storing household products in glazed ceramics for 3,000 years or more. Obviously vinegar (acid), pickling brine (alkali), whiskey(alcohol), and a myriad of salts and oils have been kept in masonry containers long term. Surely it follows that there were glazes capable of keeping the various solids and liquids from either attacking the container, or being attacked by it. If so, then at some point in history there must have been a lot of (low cone, simple composition, widely used) glaze recipes used for just these purposes. Where did they go?!? Like most people I can appreciate a "glassy luster, light crackle, smooth cobalt blue glaze", but if I *use* the vessel, I'll need to know if it's going to deposit toxic cobalt oxides in my raspberry preserves. So two questions: 1) Do you know of a "solidly food safe" glaze that's got a simple composition and low cone glaze temp? 2) Is there a book or online resource (or should there be one?!?) which covers "practical" glazes? Thank you kindly, -Jeff P.S. I've been wondering if a 50/50 kaolin/borax glaze might be possible, but I'd rather have a historic, proven starting point. P.P.S Email me or reply to this thread - I'm eagerly listening.