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Dick White

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Everything posted by Dick White

  1. The 0.42 is the amount of MgO within the Seger Unity (AKA UMF for Unity Molar Formula) of all fluxes totaling to 1.00. The 9.79% is the percentage of MgO by weight in the total recipe. The 13.17% is the molar percentage of MgO in the total recipe.
  2. I have not tried that specifically, but my general knowledge of ceramic glazes is that would not work. The raw glaze needs to adhere to the surface of the ceramic body, and if there is anything in between, such as dirt, dust, oily residue from fingers, stray wax from the bottom, etc., the glaze will shrink back from that dirty spot as it melts. I would think the gesso will do the same.
  3. The probable reason it is rated to only cone 6 is the blank ring in the middle. That adds volume but no additional heat. The blank ring can be removed to improve the watts to volume ratio, but that would limit the size of things you could fire.
  4. Bill's suggestion that your ware is probably underfired is a good one. Before you refire it, you should determine why the kiln failed. If it failed this time, it will fail again when you refire.
  5. You have the basics from the UToobs. As for timing, I set the bottom switch only on low for as long as the ware is still damp. This warms it up from below. You can test the humidity coming out of the kiln by holding a small mirror or piece of glass by an open peep hole and any invisible steam coming out will condense on the colder glass. When no more humidity is coming out, you can start the bisque firing by turning all switches to low for an hour, then twist them all up to medium for an hour or so, and then up to high for the remainder of the firing. Be aware that the kiln sitter is designed
  6. Those are what are known as infinite switches. Unlike switches that click to a specific position, e.g., on/off like a sideways light switch, or a rotary off/lo/med/high switch, these switches are akin to a dimmer that can be set anywhere (an infinite number of positions) from off through full on. When the pointer is at low, it turns the elements on for a short time (a few seconds) and then off for a longer period. When the pointer is closer to high, the elements are on for a longer time and then off for a shorter time. The numbers 0 through 100 are not exactly the percentage of time that the e
  7. Direct copy and paste from the Mason Color Works FAQ: WHEN I USE BLACK STAINS TO MAKE GREY SHADES THEY TURN GREEN/BROWN/BLUE/PINK ETC. WHY ARE THEY NOT SIMPLY GRAY? Do not use black stains to make gray shades by using small amounts in the glaze. Blacks are made of combinations of cobalt, iron, nickel, chromium, manganese, etc. If low percentages are used, the resulting color is often that of the predominant oxide in any particular black pigment. Care should be taken to use the correct glaze chemistry to avoid combinations that create color problems. It is better to use the gray pigmen
  8. The FireRight top knob is an early version of automating the ramp up in temperature. The numbers on the dial approximate the number of hours it will use ramping up from cold to full heat, so you don't have to go back every hour and turn up another regular switch. I'm not exactly sure what the bottom knob does or why it should be set to a particular number. Need to know the make and model, as Bill suggests, to find a manual for it. I have recollection of an old kiln that used the second knob to set a final power level dependent on what is being fired. The kiln sitter, of course, is a final shut
  9. If you are in a commercial location with only 208v available, the kiln rated for 240v will be about 15% underpowered, and thus will probably reach only bisque/low-fire earthenware temperatures. Mid-fire cone 6 is highly unlikely. The switches and controls will still work. What is not working are the elements. If you replace the elements with ones that are designed to give the full temperature from 208v, then you should be able to get cone 6 from it.
  10. As others have noted above, there generally isn't much difference in the outcome with EPK and china clay. One glaze where I have noticed some difference is a true iron celadon in reduction. EPK will push the tint towards green while using English Grolleg will tend towards blue. But this is the only time I've seen a difference.
  11. I have fiddled with mica some, using it in sodium silicate stretched/crackle forms, and then a modified very low temperature (cone 018ish) raku-like firing to put in the smoke bin to carbonize the crackles. The issue is that the fun colored mica products are for cosmetics and soap (bath bombs) and they either melt out at hotter than ~1400F or the color burns out. There are a few types of mica used in ceramic bodies that hold their own at the higher temps, but you have to order them specially and they don't have the fun colors.
  12. Perhaps she had neverboiled water for tea on the stove and watched the steam come out of the spout of the kettle. It's not the paper burning, it's the water exploding.
  13. The kilns in our college studio are in a fireproof solid cinder block room with 2 more block walls to the hallway where the AP is. No wifi for us in there. Fortunately, they are old style V6-CF controllers, so all I can look at on my phone are my home kilns.
  14. Just an FYI, for the phone app to work, you need to have wifi internet available at the kiln. The controller communicates via the internet to a cloud server maintained by Bartlett, and the phone app logs into that same server to read the data. You may already have wifi in your classroom, but if your school doesn't have it, then you'll have to work with the IT department to get it.
  15. Yes, petalite is classed as a feldspar. Petalite is more often used in clay bodies than glaze, so that's why I didn't include it in my comments about feldspars in glazes. But you can use it if you have it. As for the foaming/washing issue with spodumene, a soap is used during the crushing and processing of the ore, and traces of it remain on the final product. When mixed with water in the glaze slurry, it will generate its own miniature bubble bath, which can cause problems as the glaze dries on the ware leaving bubble voids which become pits in the fired glaze. The soap can be eliminated by w
  16. The sitter bar is not "bent nicely." In a properly calibrated sitter, the bar or mini-cone is bent to a 90┬░ angle for the claw on the outside to release the drop plate. Yours is bent less, so it released early. Hence the hard cone 5 not yet cone 6 result. If you don't have one, get a calibration disk and adjust the sitter claw and drop plate. There are uToob videos how to do that. dw
  17. Thuy, welcome to the forum. Please tell us what cone/temperature you fire to. Glaze recipes are dependent on the temperature to which they are fired. The upper picture appears to be a layered application of two glazes, and tghe lower picture appears to be a raku glaze.
  18. Kona F4 was (again, "was" is the important word) a soda feldspar mined in Spruce Pine, NC. A bit before the turn of the century, there was an unfortunate fire in the mine, and it was uneconomical to repair and reopen. End of Kona F4. There was another company mining a soda feldspar on the other side of the same mountain. That was named NC-4. For whatever marketing reasons, the company selling NC-4 decided to change the name to Minspar. So, if you ever run out of that historic bag of Kona F-4, Minspar is almost the same. In some areas of the world, the feldspars are typically not sold by brand
  19. We had this very discussion a few weeks ago with a different person who had a new-to-them Paragon kiln with a similar issue that the controller limit was set lower than the rating of the kiln, and thus made the kiln unusable at its full rated temperature when the controller cut out too low. The user manuals from Paragon all claimed this could only be adjusted at the factory, but @Bill Kielb found an instruction page that indicates how to get into the special options menu of the controller and fix this. Below is the page he found.
  20. This is a question for the knowledgeable electrical engineers in the audience. I am trying to remotely help an acquaintance far across the pond who is having trouble with her kiln taking too long and tossing E1 errors. There are no proper kiln technicians in her area, so she must rely on a local sparky to do the necessary maintenance and repairs. We have been tossing ideas back and forth, including information reported to her by the sparky. One issue is her house appears to be suffering some voltage drop, but a review of the log of a full power test shows a severely lagging ramp of between 30
  21. Some history and clarification about the G200 series feldspars - G200 was (the important word: "was") a potash spar roughly equivalent to Custer at the time it was in production. The G200 mine in Monticello, GA began to run out in the early 2000s, but they were able to keep the brand going by using a feldspar from another mine in Siloam, GA (about 50 miles distant). That feldspar, however, was considerably higher in its potassium content. They resolved the chemistry by trucking a soda feldspar in from Spruce Pine, NC (about 250 miles distant, probably from a mine near the Minspar source and th
  22. 1. Get a 5 gallon bucket for each bag you want to reclaim (or just a few buckets and work through the clay a few at a time). 2. Open a bag and pour one or two cups of water into the bag around the dry block of clay. 3. Put the bag in the bucket. I like to leave the top open for now. 4. Start filling the bucket with water. As the water rises in the bucket, it will expel the air from the bag. 5. When the water in the bucket reaches just above the level of the top of the block of clay, seal the bag with a twisty wire or rubber band. There will be only a little bit of air left
  23. If the glaze has been fired, it is permanent. No household or hardware store chemicals will remove it. If the glaze is just a mistake on the bisque ceramic, usually it will wash off with water.
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