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BlackDogPottery

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  1. single firing, cone 6 stoneware

    I have one of those too that I throw all my unused white glazes and sometimes a little bit of slip. Interesting thing to see how some of the whites change to the creamier side or grey side with usually a few soft specks of cobalt and copper (from the clays I guess)
  2. Rutile Glaze

    Update. I added rutile to my base glaze and it didn't come out anything like I would imagine. 4.5% Rutile . A soft grey that unusually turned black manganese specks to an orange rust. Bizarre to me as I was expecting a yellow. However its pretty nice to me and cant wait to use it. https://imgur.com/leYKL0Z 4.5% Rutile : 4.5% Red Iron. Even more surprising was this odd shade of black https://imgur.com/OEQTuvv
  3. Plaster clay

    Has anyone heard of this before? http://ceramicsfieldguide.org/pdf/uncommon-clays-glazes-processes/PlasterClay.pdf Seems like it fires extremely low but I cant think of much that you would use this for. My guess are those plaster wall decorations/ plaster picture frames. I've heard of people adding plaster in glazes but a plaster based clay?
  4. single firing, cone 6 stoneware

    I've been single firing for a quire a few years now and in my experience just about any glaze will work but the main issue you run into is having the glaze stay put. Some glazes with Gerstley Borate will gel on their own and apply evenly and stick to the pot. Others require Gum Arabic to stay on or they flake off and this always leads to crawling. What works for me and glazes that wont apply nicely is 4 grams of Gum and 80 grams of water per 100 grams of dry ingredient. This will require about 3-4 coats but you can cut the water in half and apply in 2 coats, cut it again and apply 1 coat. Depends on how thick you can get your glaze before its unbrushable. Some recommend leather hard glazing but I find bone dry because if you glaze on leather hard the clay continues to shrink but the glaze doesn't (it flakes and falls off). You can also pour the insides at bone dry just dry it out slowly. Depending on how far you want to go you can also mix certain clays together as some react better to water absorbtion. My stoneware always cracks but adding in 1/6 of Terra Cotta helped it go through the shock of water and after firing the bonus of a stronger feeling clay body. It just takes a little patience and a little courage.
  5. Would just like to mention that I believe the toxicity of iron oxide in glazes is a fraction compared to it's use in multiple cosmetics. Lipstick, eyeshadows, blushes, and whatever else are applied directly to the skin, digested, or inhaled. You get the point, very rarely do you ever hear reports on that as it would most likely be linked to lung issues than an overdose. Also wonder about the effects of gold and other luster. There's plenty of dishes with rims lined in gold or silver. I'm sure if there's any way of it coming off it must be extremely minute, but it's something to think about.
  6. Zinc in glazes

    "The use of zinc in standard glazes is limited by its price, its hostility to the development of certain colors and its tendency to make glazes more leachable in acids (although zinc itself is not considered a hazardous substance)." From Digitalfire https://digitalfire.com/4sight/material/zinc_oxide_1718.html . I also have an old 70 ceramics book that more or less notes the same thing. Just curious.
  7. Zinc in glazes

    Sorry if my question missed the mark but I was meaning is the zinc leachable after firing. As in a zinc glaze inside a coffee cup.
  8. Zinc in glazes

    It's definitely a good opacifier. I ran a test substituting the zinc with borate plus another 10% borate. The difference was night and day. The zinc version was very opaque with a nice smooth surface, off white. The gerstley borate trial was clear as it could be but crazed all over and cracked the piece in half from thermal expansion I believe, the surface however was smooth but felt cheap like imported earthenware.
  9. Zinc in glazes

    Yes, that's it. It mentions zinc can leach but it's not a hazard unlike copper or cobalt. But it made me wonder why use something that could leach when there's other materials like borate that could do the same thing? Is there pro's and con's with using zinc in a glaze besides being an active flux?
  10. Zinc in glazes

    I was going through more glaze research and came across an interesting note on zinc being easily soluble in glazes when strong acids are present. I've seen a few glazes with zinc and one I use myself. From what understand zinc is a flux. Is it uncommon or would it be practical to replace zinc with some kind of frit or borate if its so easily to dissolve in a glaze?
  11. Pitting and pinholing

    Is this on the inside as well? Could be from trimming too. I've noticed pinholes on pots that only appeared where it was trimmed (bottom 2/3 of a pot). It seems throwing seals the clay off in the interior and elsewhere. I would try sponging the whole pot down next time and see if it makes a difference.
  12. Handy Techniques

    Big ol box of 6" x 6" bathroom tiles. Use them for bats. Sure are a lot cheaper than the bats you can buy at the supply store. They stick pretty well to the wheel head and cant warp!
  13. What's your Mug?

    As the title says. What's your mug? Almost everyone has a favorite mug, what's yours? What do you grab in the morning? A stout standard cafe mug or a bulbous mug that can quench an army? I'd like to hear!
  14. Red Clay

    Another update. 50 : 80 mixture. A completely matte stone like finish, black without any trace of brown and nice to the touch. No runs.
  15. Handle Help

    Update. Put handles on a lot sooner, added a coil of clay around the seams, blended with a tool, and dried way slower under plastic. I believe that was the problem, speed drying on top of a hot kiln what was I thinking lol? So far so good. Lets see if they can survive being raw glazed!
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