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Everything posted by neilestrick

  1. Have you decided where the kiln will be located, how you will be venting it, gas supply, local safety codes, etc? Gas kilns are not as simple as electric. Lots of prep work before buying one....
  2. I use Speedball. It's really cheap compared to Amaco and Coyote, and the colors hold up well at cone 6 for the most part. The red and royal blue have some issues with bubbling at cone 6, but I'm working on fixing that.
  3. With gas kilns, in general the burners either work or they don't. There's not much in the way of maintenance or parts that wear out like on electric kilns. So assuming the burner system works, I'd be most concerned with the condition of the bricks. Downdraft kilns tend to fire more easily and efficiently, but updrafts work just fine once you dial in your settings.
  4. You should be able to get that kiln to reduce throughout. They're great kilns once you get the setting dialed in. You need to make sure there's back pressure out both spy holes during reduction. One will have a lot, the other just a puff. If you've got back pressure out both, then you know the atmosphere is the same throughout the kiln. You have to find the balance between the damper, gas and air to create the degree of pressure and reduction. If you're not getting back pressure out the bottom spy, then you need to close the damper some or increase the air and gas.
  5. If they're seated well at the corners they shouldn't flop out.
  6. For a chimney the lower rated bricks should work fine. Worst case, they will shrink a bit over time and need to be tightened up.
  7. The pitting doesn't hurt anything, and powder coating will wear off.
  8. If there are larger than normal gaps in the coils, you can squeeze them together with needle nose pliers.
  9. Your class may not involve a lot of technical info, so ask a lot of questions, and ask your teacher if you can help load kilns and mix glazes.
  10. The wax that Ceramic Supply Chicago sells will rinse out of brushes with just water. Awesome stuff.
  11. With L&L elements, they must be seated into the corners when you install them. They ship the elements slightly short, so that means either putting them into the corners so they're springy and under tension, or stretching them further so they lay into the corners without any tension. Personally, I prefer the latter. With new kilns they tend to hold under tension just fine, but with older kilns where everything has shifted a bit it's easier to have them lay into the corners without tension. As for your predicament, they should still be quite flexible and stretchy after only one firing, so you should be able to get them into the corners without breaking them. If you have to torch them, do so, but I don't think you'll need to. A little bending here and there with needle nose pliers, and possibly crimping the coils back together where it's drooped a lot and you should be fine.
  12. You're asking for an awful lot of info, more than we can give you here without pages and pages of typing. It would be good if you could pay the previous owner to spend a couple of days walking you through the entire process. There are a lot of variables that will be specific to your studio depending on what types of equipment you have and what type of slips and glazes you are using. In ceramics, hands-on experience is the best teacher. It would also be good to take a ceramic class from a local art center or community college where you can learn about working with clay and firing kilns. You may not get any experience with slip casting there, but you will get a lot of good general knowledge about clay, glazes and firing.
  13. If you're using the preheat function, it takes approximately two hours to get to 200F (60F/hr climb) before it starts the hold time you programmed. So about 7 hours if you back out the preheat, which means your firing time was not too long. If anything it went a little fast. There's always some variation, though, so I wouldn't worry about that. I'd do the cone offset. Start with 10 degrees like you were thinking. The 18 degree offset is in the thermocouples, not the cones, so you won't see that when you do the programming. The rule is do a thermocouple offset when it's inaccurate at all temps, do the cone offset when it's only off for the cone you're firing to. It may very well be off at cones 5, 7 and 8, too, but if you don't fire to 5, 7 or 8 it doesn't matter. Since it's correct at bisque temps you should do the cone offset.
  14. In general, brushing on top of a dipping glaze can be difficult. Because the dipping glaze doesn't have the hardeners and binders in it, you may find that the brush picks up the dipped glaze rather than just going over the top of it. It will depend on the makeup of the glaze. Those with higher clay content will probably work better. I would also do the brushing glaze before the dipped glaze is totally dry. If glazes can have a leather hard stage, that would be the time to do it. Like when it's dry enough to touch but not totally bone dry.
  15. My thought on the bubbly underglazes is that they're in that in-between stage where they are melting more than the others, but not enough to melt out and smooth over. I think stiffening the underglaze could also solve the problem. My concern with adding frit to the underglaze is that it may reduce the porosity after bisque firing, making glazing difficult. I'm going to run some tests both ways with the Speedball red and see what happens.
  16. The problem is as I described above. The additives in the underglaze that make it brushable are preventing a good glaze coat. Try applying your underglaze at bone dry and then bisque firing. The underglaze will go on very similar to on bisque since bone dry is very porous.
  17. This is an excellent point. I fire down in my baby kiln, to match the slower cooling rates of my bigger kilns. My glazes look terrible when cooled fast. Just awful.
  18. Some underglazes can also get rough because they flux out too much at cone 6. Speedball red and royal blue do that. If you fire them raw, they actually start to gloss over a bit. With glaze on them they bubble and come out rough.
  19. We see a huge difference across all brands of underglaze on how the glaze goes on depending on whether or not the underglaze was bisque fired. Amaco seems to be the worst, but it happens with all of them. The binders that make the underglaze brushable act like a shell, making it less porous than the raw clay, and therefore giving a thinner glaze layer. If you bisque fire the underglazes, the binders burn out and it's not an issue. Thickness can definitely be an issue, too, but ronfire could be getting a double whammy if the under glaze is too thick and not bisque fired before glazing.
  20. It would all depend on what type of clay you're using, what forms you're firing, and how thick and evenly constructed they are. Lots of variables. Remember that raku firing uses very under-fired bodies, which handle thermal shock better than vitrified bodies. I've got a little test kiln that I can get to cone 6 in 5-6 hours, and it can cool fast enough to unload 5-6 hours later. It's so small that there's not much mass to cool down, though. My big kiln takes more like 32 hours to cool because of how much work is in there. Cooling it by pulling air though is a tricky situation, because it won't cool evenly that way. You can crash cool down to red heat without much problem, but getting through quartz inversion in a rush is tricky. If I remember correctly, tile companies that turn them around super fast are dry pressing the tiles under extreme pressure, which makes for a very stable form. Plus tiles have very low mass, and if they're doing non-vitrified wall tiles, they don't have to worry much about warpage.
  21. If the underglaze is being applied to bisque ware, the binders in the underglaze can prevent getting a good glaze layer when dipping, regardless of the thickness of the underglaze.
  22. Whatever you're putting the stain in can affect the color of the stain. That's true for clay or glazes. The percentage of stain will also affect the color. You'll want to test it from about 3% up to 20%, depending on how strong you want the color. How hot you fire and in what atmosphere will also affect the color. Many stains will color shift above low fire temps. Your clear glaze can also affect the color. For the best results as far as having the slip fit the clay body, you should make the slip out of your clay body. 1. How hot are your firing? 2. Oxidation or reduction? 3. What percentage stain are you using? 4. What glaze are you using?
  23. When are you applying the underglaze- before or after bisque?
  24. In a Peter Pugger, there is only one chamber. It's not the same as a pug mill, which has a chamber in the middle between the intake and the extruder specifically for the vacuum. https://peterpugger.com/history/how-peter-pugger-works/
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