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Dick White

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  1. For Flux Sake is one of the offshoots from the inestimable Matt Katz, who in one of his webcasts long ago expressed an opinion that in addition to the usual list of pinhole suspects, poor application of the glaze was often a cause, particularly with brushed glazes. If the first coat of glaze had irregularities, those nooks and crannies could be covered by the next coat, leaving a tiny air pocket underneath. The problem is especially acute on textured surfaces. As the glaze melts during the firing, those little air pockets would rise to the surface and pop, leaving the pinhole. So, in Matt's opinion, pinholes could be from user error as well as decomposition of the glaze or outgassing from the body. Matt typically uses porcelain tiles for his testing, and bisques to 08 for consistent absorbency. A clean body such as porcelain does not need the higher bisque to burn out the organics and impurities.
  2. Dunno, I don't have a Skutt Touchscreen, and the "user manual" is a help screen embedded in the controller. All I know is what I hear from others who are struggling with it.
  3. Sometimes even when the elements look good and turn red, they are worn. The only way to definitively determine the health of the element is measure its resistance with a meter. The L&L manual kilns have variable controls for each section. If the bottom is running cool (common), you can compensate for that by have the bottom dial on full high and the middle and top a bit below high. You'll have to experiment with that until you learn exactly how your kiln behaves.
  4. @Bill Kielb and @Potpotpotter The Skutt Touchscreen controller, while built by Bartlett to Skutt's specifications and similar in many ways to Bartlett's own Genesis, does not have the toggle to turn on the optional cooling segment as the final segment of a cone-fire (auto-fire) program. Such a capability was available in the Skutt KM series kilns using the controller logic adapted from the Bartlett native V6-CF controllers, Skutt removed that from their Touchscreen version of the Bartlett Genesis. With a Skutt Touchscreen controller, one now must build a custom ramp-hold program that mimics whatever cone-fire program on the way up and then add one or two more steps at the end of the program for a controlled cool.
  5. Many years ago, one of the students in the college class lost the bottom nut from the extruder die holder while cleaning it in the cleanup bucket in the sink. Irritating, but not the end of the world to have to go to the hardware store for a replacement nut. We periodically scoop the sludge from the cleanup bucket into the main recycle barrel, and when that barrel is full, I pug the recycle in to a proprietary mix that is so proprietary that even I don't know what I put in the pugged clay logs. Despite the unknown mix, it's usually nice enough to work with for class demos and experimental practice work. About a year and a half later, I was making a batch of Empty Bowls, and felt a lump in the wall of the cylinder. Thinking it to be an air bubble, I poked it with my needle tool, but it was a hard chunk. So I dug it out, and there was the long lost nut.
  6. There is some conflicting information about the first firing floating around, both from different kiln manufacturers, for different purposes, and even within the same manufacturer's instructions. L&L's printed manual has long instructed owners of their new kiln to do an initial break-in firing of the empty kiln (but with the furniture) slow bisque to cone 5 (yes, five, not oh-five) with a 3 hour preheat for the dual purpose of seasoning the elements to develop a protective oxide coating and to set the cement used during manufacturing to hold the kiln bricks together. Their newest manual indicates these instructions are for both the Dynatrol and Genesis controllers. Conventional wisdom by some other kiln manufacturers instruct owners of their new kilns to do the initial firing slow to 04. This is consistent with the recommendation from the manufacturer of the Kanthal elements for seasoning newly installed replacement elements, again to develop a protective oxide coating on the wire. Out on the interwebs, many commenters who own these other brands of kiln will adamantly (but incorrectly) assert that new owners of all brands of kilns should do the initial firing to 04. And now we have this new video from L&L for programming the first firing on a Genesis controller that instructs a glaze firing to 04 with a 1 hour preheat. However, if one looks around on the L&L website, there is another video for programming the older Dynatrol controller for the first firing that is consistent with the printed instructions, i.e., slow bisque to 5. Is the basic kiln constructed differently for a Genesis vs. Dynatrol controller that it would need a different initial firing? I don't work there, so don't take my word for it, but the conflict seems fishy to me. With 3 instruction sources to choose from (the printed manual and 2 videos), I would go with the 2 that are consistent, i.e, the printed manual and the Dynatrol video. But maybe that's just because I am a recovering accountant...
  7. DigitalFire can tell you about the usage of most of those. https://digitalfire.com/material/list
  8. Ok, now download the firing log and feed that sweet thang into @jay_klay_studio's graphing program to visually see the tracks of the 3 sections. And if you really want to have some fun, add another 9999 drop all the way down to 100 after your regularly programmed cool to log how looooonnnggggg it takes for the last several hundred degrees. Several times over the years I've printed the extended graph of a few kilns as a teachable moment for the students of the virtue of patience, i.e., "Can I get my piece tomorrow?" "No, next Friday."
  9. For the brush hair, you can go to a full line fishing store and get squirrel tail and deer tail used to tie fishing fly lures.
  10. The reason most studios are picky about not allowing outside clay is because of the risks involved in the glaze firing. Earthenware bodies or glazes mistakenly put in a mid-fire glaze firing will create a terrible mess. "But the label on the box had a number 6 in the cone rating. Oh, the zero in front of the 6 was meaningful? How was I supposed to know that." (Yes, I have had that very conversation with students.) The other side of the issue is just about all bisque traditions are similar no matter the intention of the body in the final glaze firing. So, bisque firing a low-fire raku clay to cone 06-04 is no different than bisque firing a cone 5-6 clay to the same 06-04, or even a cone 10 clay bisqued to the same 06-04. My guess is if you respectfully talk with the studio management about your opportunity for the raku firing and ask them to bisque fire this non-standard body, hopefully they will understand there is no risk and accommodate your special request.
  11. @Bill Kielb alludes to an important aspect of a kiln vent - make up air. For whatever air is being exhausted, there must be an equal amount coming back into the room. The challenge for a kiln vent, is that make up air must come from a different direction from the exhaust. If the location of the make up air, such as another open window or door in the room, is too close to the exhaust vent, the stinky air will just be sucked right back in through that opening. The make up source needs to be around the corner from the exhaust so that the stinkies dissipate in a different direction and the make up air is clean.
  12. The Bartlett and Orton controllers have an algorithm (designed by Orton, licensed to Bartlett, so both have it) built into the cone-fire mode that senses actual heating rate (which may or may not be what was programmed) and adjusts the final temperature for the intended cone bend. As @Bill Kielb notes, the Orton tables focus on the last 100C/200F, and the published cone-fire firing schedules for Bartlett controllers all start the final segment at 250F below target temperature regardless of cone or rate. In my kilns which are all performing well, the Genesis logs show this happening as programmed; the final ramp at medium speed is a straight line at 120F per hour. What I do not know is, if the kiln were faltering in the final segment, does the controller average the achieved rate over the segment, or adjust incrementally as the segment progresses. In some of my diagnostic work with others' failing kilns, the rate of increase may be reasonable at the beginning of the final segment, but slows down significantly by the end of the segment (i.e., the graphed temperature is a curve, not a straight line) so how does it calculate the appropriate end point? What does this mean for your programming? I don't know, just throwing it out there that many potters think that if the controller finished without an error code, their kiln is in good shape, when it is not. The controller is working around the kiln failure. You'd like to mimic that, which is awesome.
  13. Do not replace the 50 amp breaker with the required 60 amp breaker unless the wire is 6 ga. or better.
  14. When defloculating with sodium silicate, a funny thing happens if you go too far. It begins to thicken rather than get even thinner as you would expect. And you add more and it gets worse. Solving the problem requires understanding how defloculation occurs. The clay particles are sensitive to the acidity or alkalinity of the water. If the glaze slurry is too loose and separating quickly, a small dose of an acid, such as epsom salts or vinegar will flocculate it. If the glaze slurry is too thick, a small dose of an alkaline, such as sodium silicate or soda ash, will deflocculate it. But, as mentioned, if you deflocculate with too much sodium silicate, it starts gelling. Because the underlying problem is too much alkalinity, you just need to neutralize it with some acid. It seems crazy to flocculate this glaze that has gotten too thick from over defloculation, but that is what you need to do. Scoop out some and try it with a few drops of saturated epsom salts solution or vinegar. p.s., in your recipe, did you mean manganese dioxide instead of magnesium dioxide?
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