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tinbucket

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  1. tinbucket

    Making a cone 04 clay go to cone 10

    Not only try "cutting it" with a high temperature clay, do a line blend! At least 20/80, 50/50, and 80/20. Absorption/shrinkage bars should give you some idea of what's going on. Also, I'm assuming you are firing cone 10 reduction, and cone reduction will effect the fluxing action of iron more than oxidation will, I'm sure others can give a better explanation of this - my understanding iron in reduction = more melty/stronger fluxing
  2. Fireclay will be slightly more refractory and have greater thermal shock resistance, they might last a little longer. If you don't have fire clay you could make it out of your usual stoneware. Build them sturdy and they should work. If I spent a long time on a single spoon I would be inclined to test my racks with some weight on them before firing a glazed spoon. Up to you. Maybe others can chime in. I have never done this, I just got the idea when you posted your question. If your spoons are light you could try them on a premade bead rack, but I would be weary of putting anything heavier than beads on a bead rack
  3. The are called insulating fire brick (IFB) or soft brick. They are much less dense and therefore absorb less heat than typical hard brick (good if you want fast temp rise/fast cooling/less energy use and not good if you need to retain heat or cool slowly). Almost all electric kilns are made from insulating fire brick. My suggestion for the spoons would be to buy some thick high temp wire and build your own "spoon hanger" out of Hawthorne or similar fireclay. Make it so that each spoon hangs with support on each side from an unglazed hole on the spoon handle. By making your own you will maximize the efficiency of firing/stacking space and ensure that the spoons are not all hanging together on a long span of wire.
  4. tinbucket

    Cone 6 Red Stoneware Recipe

    Thank you neil, that is something I never would have considered. Maybe I can add enough to get a color response without lowering the thermal expansion too much.
  5. tinbucket

    Cone 6 Red Stoneware Recipe

    Thanks again, nerd. What about Lizella is problematic? I really like the coarse texture it gives a clay body
  6. tinbucket

    Cone 6 Red Stoneware Recipe

    Nerd: Thank you for the considerations, I am very much willing to test any suggestions. I have considered frit but I am heard the firing range can be very narrow when used in a body and it can make the fired ware brittle. I will definitely give that a shot. I have heard the same about using redart in a stoneware body, something about the fluxes effecting the the overall body differently because it is an earthenware. Some sources of iron I have considered so far: Redart, Newman, Lizella, Laterite, and Yellow Banks. I will look into sources of potassium, I may not need additional flux if I am using earthenware to lower the vitrification temp of the body. GEP: Thank you for the suggestion, but I am in a ceramics program at a university that requires me to mix my own clay. Also I think it will be a valuable experience to design a clay body to meet my specifications.
  7. I am looking to develop a red/orange clay body for cone 6. I will be using the clay for throwing functional work so I would like it to be vitreous (or low porosity) and have some degree of plasticity. I have read for earthenware that as you approach 0% porosity the iron is dissolved/fluxed and you lose the bright orange-red color, moving more toward red-brown. Is the same true for stoneware? I will be scouring the internet for recipes and begin testing materials that I think will be useful. I have considered using a virteous stoneware recipe and coloring it with mason stains, imagine a clay with the color of terracotta and the tightness of porcelain. I think this would be very costly and unnecessary, but I will test it just to see the result. Any information/thoughts on the subject will be greatly appreciated - thanks in advance.
  8. tinbucket

    Curious about porcelain

    I'm not sure about this particular porcelain, but Vee Gum is a plasticizer give clay a pink color when fired. It is expensive but also very low iron and very plastic so it is used in some porcelains.
  9. tinbucket

    terra sig vs. slip

    I asked my friend a very similar question recently and she prefers terra sig because it is like the pot is wearing a thin veil versus slip which is like a the pot is wearing a thick winter jacket. Covering a pot with slip removes some of the marks made by the maker's hand. I have been experimenting with terra sig and although I know it is not the traditional use, I have been very happy with Redart sig at cone 6. It doesn't completely melt and is not 100% water tight, but on the outside of a pot is a beautiful deep red with a slight shine.
  10. tinbucket

    Question on mixing colorant batches

    This video will help you. The method he suggests is similar to what Mark C said. Mix 200g of glaze, add a bit of your colorant, brush a stroke on the tile, add a little more colorant, brush a stroke on the tile, and so on. One thing that may be helpful is to look at other recipes to see how much of each colorant is added. For example, 5% iron oxide might not do much to the color but 5% cobalt carb would give you a metallic runny blue (<<<almost positive). Another thing that may be helpful is to add an opacifier such as tin oxide or zircopax to some of your tests to see how it changes the color. There's also the possibility of colorant combinations, many of which are documented in glaze recipes. There is also a John Britt video where he demonstrates the method you originally suggested but I think the above method is less wasteful and more efficient.
  11. tinbucket

    Making terra cotta bricks

    I would say skip the lime. I'm thinking the recipe above was for bricks that were not fired/not ceramic and rather aggregate cemented together (like concrete). Large chunks of lime are undesirable in ceramics (I believe they absorb moisture after being fired, expand, and create holes in the fired surface - search lime pop out). I'm sorry to hear about your cracked bricks, I would try 50/50 clay and coarse sand (40 or lower mesh). I would try drying a few in direct sunlight just to see how far you can push the drying process - or you could dry them more delicately and flip them periodically.
  12. tinbucket

    c6 glaze too soft

    In the first recipe, the zircopax may be the cause of the cutlery marking. Search zircopax on digitalfire.com and you will see more info on this. I would try a line blend of the glaze, reducing the zircopax to see how much is necessary to opacifiy your glaze. Then I would add silica in 5% increments to see how much the glaze could take before adverse effects arise. Also the first recipe that Min posted is a glaze I am testing right now. The matte surface of that glaze has an opacifying effect on its own, requiring less tin or zircopax to achieve the same opacity of your current white.
  13. tinbucket

    Ceramic Tape Recipe? (Like Keraflex)

    http://www.alfredgrindingroom.com/raw-materials/ http://www.alfredgrindingroom.com/recipes/ ^ A wealth of information on ceramic materials and experiments. The tape casting pdf is on the first link, the same one posted by two others in this thread
  14. tinbucket

    Terracotta & glaze compatability

    My first guess is what Marcia said. Bisque to a higher temperature than you glaze fire to. Red clay has lots of impurities/organic matter which leads to a high loss on ignition and off-gassing (matter burns out of the clay and produces gas, the gas is trapped by the glaze).
  15. tinbucket

    Leaving glazed pieces unfired

    Chris Gustin sprays his pieces with some type of glue (regular white Elmers, I think) after glazing to protect the glaze from chipping off before firing. I think you could easily dip them if you do not have access to a sprayer. Similar to using hairspray, which I have heard of. I'm not sure if either is better than the other
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