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  2. colouring large batches of porcelain

    One thing to check out is if you can get your clay dry, not already mixed. That eliminates the need to dry it out to get a powdered form. Many clay manufacturers sell their clay dry.
  3. what is your favorite wax resist?

    Forbes Resist. Freaking amazing.
  4. Absorption

    One test you can do to see if your clay has vitrified, is to fill it with water and let it sit of a surface all night. In the morning , if there is a ring of moisture at the base, the clay is not vitrified. When working with outdoor freeze proof clay, there are a few differences of opinion on what rate is preferred. Nothing over 3%. Some say 1.5% Marcia
  5. Looks good. Did you have any problems? Marcia
  6. For anyone interested, this is the sculpture now.
  7. Today
  8. During the Sunshine Cobb demo/workshop this past weekend at the Red Lodge Clay Center, the topic of wax resist came up. One person said the Wax resist from Columbus Clay was a "game changer". in Montana, many people have used the Liquid Wax from Archie bray developed in the 1950s for Hamada's visit. I have been using Aftosa wax for several years because I can see it. Its blue. Anyone have a favorite? Marcia
  9. winter came last week with 6 inches of snow. I have a lot to do before the extremely cold weather gets here. 

  10. Absorption

    Agreed with Neil, I would also try for a full cone 6. For large standard cones it’s tip touching the shelf for a full cone 6. With self supporting cones it’s tip level will the top of the wedge shaped base. (If you go tip touching shelf with the self supporting cones it’s only a few degrees more so that is okay too.) Some clays have more wiggle room than others. In my experience the closer to 0% porosity the less you can overfire without running into the occasional bloat or slump. I don’t have enough experience with US clays to know how much you can overfire the Standard Clays. I looked up the Standard 563, it’s listed as 1% @ ^6. But don’t forget that fudge factor of + or - 1%, gotta do your own tests to see if it’s okay for pots holding water. Sounds like an uneven kiln is not a problem, good. I didn’t know what you had so was trying to cover all the bases with my earlier comment. Couple thoughts re what is vitrified and if it will leak. Guess it depends on how you define vitrified and mature. I go with if the fired clay is impermeable to water then it is vitrified. (ie it doesn’t leak at all). Mature is not necessarily vitrified. Example would be practically all earthenware clays. They mature roughly somewhere between 04-2 but the porosity (how much water they soak up) is never going to be near zero, generally in the 10%+ range. Yup, they are mature, nope they are not vitreous. So to answer your question, your ^6 clay likely isn’t vitrified if it isn’t fired to maturity. Your wide range 6 - 10 clay is not fired to maturity at ^6 therefore no way will it be vitrified nor mature.
  11. Kiln Install on Deck

    Guys, maybe take it down a notch. The simple act of walking is responsible for more deaths, injuries, and property damage than dryers and kilns combined (to the tune of orders of magnitude greater). I get that you feel a responsibility to correct information, but it gets a little heavy handed and ego based--especially lately--the point of a lot of threads has been lost because of it.
  12. Kiln Install on Deck

    Clothes dryers are a major cause of house fires, about 3,000 per year in the US. Cleaning out the lint catch is super important to prevent fires.
  13. Kiln Install on Deck

    I explained to my agent, that a properly installed kiln, isn't a whole lot more dangerous than a dryer, electric or gas. In fact, after replacing the element, in a dryer years ago, my dryer scares me more than a kiln! When I went to remove the element, the surrounding area was just coated in dryer lint. The elements had none, probably because any lint that hit the elements vaporizes instantly. But it doesn't seem like it would take much to get a good fire going inside one of those. Also, a force air gas furnace or boiler heating system, have open flames, that could obviously cause issues. Homes are deathtraps, why do we live in them again?...
  14. Absorption

    Ideally we want absorption under 2%, otherwise it can weep and it's not vitrified. Half a cone may or may or may not matter- it all depends on the clay body. If your glaze can handle it, go for a full cone 6 by adding a hold time at the end. Start with 5 minutes and increase by 5 minute increments, or put on a 30 minute hold and watch the cones to see when it's done and shut it off manually one time. But that means being there to monitor the end of the firing. Shouldn't take more than 10 minutes hold
  15. Kiln Install on Deck

    Some insurance companies won't cover them at all. Some don't care. Some charge extra. It just depends on the company. But always check it out first, and do everything by the book so there's no trouble later on.
  16. Absorption

    I picked up some 563 and tried it this afternoon. It was a little soft but easy to throw. I will see how it fires. I will also check with my supplier to see if they have 630, if not I will have them order some and give it a try. Min, I have an L&L kiln with 3 thermocouples and it's pretty much the same on all levels at cone 6 but not at cone 04. Is there any "wiggle room" for a cone 6 clay to be fully vitrified? If the pyrometric cone is at 2:00 is that close enough and if not am I better off bumping the hold time up a little and risk being over fired? Are you saying that if the absorption rate is high enough that a vitrified piece will leak? Thanks to everyone for the suggestions and help.
  17. Kiln Install on Deck

    Yeah Neil, I've often heard that if you have a kiln, make sure you tell your insurance company. Because if there's a fire in your house, and it even looks like an undisclosed kiln caused the problem, you are out of luck... And by luck I mean money and possibly a home. I contacted my agent, and once I explained to them, what exactly I mean by kiln and "firing", they said it wasn't an issue. It added maybe a few more dollars to my premium each month. This is contrary to what a colleague recommended, who said "If you install that kiln in your house, don't tell the insurance company!" He was under the impression that I would be charged and arm and a leg, just to have the kiln.
  18. Kiln Install on Deck

    In addition to safety issues, there are liability issues with not installing the kiln according to manufacturer's recommendations. Your insurance may not cover you if there's a problem and kiln wasn't set up properly. Even greater potential issues if someone other than you is injured because of it.
  19. Absorption

    Cone 6-10 is a lie. It's under-fired at anything less than 10. Use clays that are made just for cone 6. Use Standard #630 instead of 182.
  20. @Tricetra -Definitely filled with symbolism, innuendo, and metaphoric implications, in addition to incense cones! He's so cute. Was your Mars in Moon or your Moon in Mars?
  21. Community Challenge #9

    Looks like someone was busy harvesting snowman brains! Nice pot.
  22. Absorption

    Standard lists 213 at 1 point 7% absorption at ^6, 365 at 0 point 6 at ^6. There is usually a fudge factor of plus or minus 1% Do your own absorption tests to determine absorption figures for your kiln and how you fire. Also, how evenly does your kiln fire? Not uncommon to have a full cone difference between the bottom and/or top of the kiln and the middle section in manual controlled kilns or kilns with just 1 thermocouple. If this is the case with your kiln then the vases need to go in the hottest section of the kiln. I would also fire some unglazed little pots with flat bottoms, put cones beside them in the kiln. Fill with water, put them on newspaper for a couple days and check the paper for wrinkling/dampness. If it wrinkles the pots are weeping. For vases I would be looking for under 1% absorption for the cone you are firing to.
  23. colouring large batches of porcelain

    For that size batch I like using a stainless steel Peter Pugger VPM 9. How I prepare the colorant depends on what it is. Some I ball mill, some I blend, some just get put in the PP with water. Starting with a 25% batch makes a mix that can be added to a white base with 1# adding 1%. I like using a progression of colors and shades so that what is left in the mixer adds to what I want. Something like dark blue to light blue to blue green to brown to tan, maybe clean it out and then yellows to orange. I run the clay through twice to get the clay in the nozzle mixed in. The vpm 9 leaves about 8#s in the nozzle, about half of which can be extruded before it is mixed with the new color. I find the density of de-aired clay much better for polished work. This might be some what dependent on the clay.
  24. I have had to fire lots of tile type projects by students over the years, as one of my projects involved tiles that demonstrated the use of 4 main forms of decoration-incising, added on clay, piercing and stamping. These tiles would be bisqued, first I would random stack with spaces between and then next layer over the layer below with spaces again between. This random stack all the way up on a full shelf at the bottom of the kiln would go up about 6-8" before I put in another layer with a double 1/2 shelf, and more tiles or pots above. Always fired slow, always to at least 11300 F. then faster up to ^06. The cool down was tricky as the kiln only had a setter, but you can block it up and fire down( I used a wire wrapped around the setter tab and drop bar to hold the setter up, then fired down slowly . . . manually. However you do it, cool down is very important. best, Pres
  25. Absorption

    I used 182 way back when I first started in my own studio. I found much the same problem. I have come to the point that now I only use clays that are ^-5-6 for that reason. I am now using their Hazelnut Brown, and a white stoneware-630 that is basically a ^6. I had wondered where your question came from, but it is quite clear now. Long range firing clays are problematic for funtional ware potters, especially if you are hoping to have pieces serviceable for many years. best, Pres
  26. @oddartist It sounds like buying one more full shelf (or two halves) is the best solution for maximizing the flat surfaces in your kiln. Please do post pictures when they're finished!
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