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About fergusonjeff

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  1. If you are really interested in a large-scale study, and have lots of money to throw at the analysis, then you could always conduct neutron activation analysis through my lab. In reality, this would be a pretty expensive proposition, but you might like to look at the lab website just to get an idea of what a study like this could entail. My day job is as an archaeologist with a partial appointment in the lab. archaeometry.missouri.edu There are some other analytical options (such as XRF or ICP-MS), but they have generally lower precision and accuracy.
  2. I have had a SS Peter Pugger for about 5 years and used almost daily. Not a speck of rust or corrosion. I use some porcelain in my mix also. I am interested in hearing how your situation turns out.
  3. I use hardwoods (mostly oak scrap from wine barrel and pallet making) early in the firing when I am looking for a slow steady climb, but in the later stages the hardwoods just burn too slow to maintain or increase temps over about 1900 degrees. Hardwood (especially oak) ash also takes longer to melt, so switching to pine for the last few hours helps reduce crusty ash buildup on the pots. Flame length can also be an issue. Pine has a shorter burn length. I have a smaller single-chamber wood kiln, so it does not matter much, but it could be harder to heat the back of the kiln the same with soft woods compared to hard woods.
  4. In a hurry this morning, but I am pretty sure this is the video that shows how to break the seal between the vacuum chamber and the mixing chamber. Not sure if just pasting the url will work.
  5. My new favorite pots are tea bowls thrown with lots of decomposed granite (from bags of chicken grit from the feed store). Works really well in cone 10+ wood fire. the granite chunks are mostly between 1/8 and 1/4 inch in diameter. Throwing is not too bad, but trimming is tough.
  6. CactusPots. I think you might be a little confused. With the peter puggers, the initial vacuum pull usually seals the back vacuum chamber, but not the mixing chamber. I usually have to start pugging for a few seconds before the seal between the mixing and vacuum chambers is broken. then turn back to mixing as the mixing chamber vacuums down. If the cap is not on while the mixing chamber is under vacuum it will not seal. I tend to overfill the chamber so as soon as you turn on the vacuum it pulls a little clay through the gap between the chambers and seals off the vacuum chamber. Starting pugging pushes clay the other direction and breaks the seal, usually in 10-15 seconds. Does this make sense?
  7. Don't underestimate the value of a pug mill. It is expensive if you only think of it in terms of recovering scrap. If that were the case my pug mill would take about 15,000 pounds of scrap to break even just on the cost of the clay, not including the labor of pugging. The real value is in being able to mix clays and to get them to the right consistency for the particular task. I make about 1/2 cone 6 electric fire, and 1/2 cone 10 wood fired work. I mix mostly commercial clays for both temperatures. I like some speckle in both, but commercial clays either have too much or too little. I can also get the moisture level just right. I want very different stiffness for throwing tall vases compared to plates. Even if I threw away scrap, the pugmill would still be the best purchase I have made for the studio.
  8. I get the same blue color from white clays in my PP. I asked the company and they said it is just a harmless reaction of clays with the dyes in the cap. I burns off with no issues. Something green that sticks around through the firing is something all together different that I have not seen.
  9. I don't use cones in my regular electric firings, but I do in wood firings. My higher temp cones (9-12) bend backwards at the tip first then drop forward. Provides a nice early warning.
  10. I have both a new Thomas Stuart and a shimpo whisper. I can definitely cause a little slowdown in the whisper with larger amounts of clay, but most items are under 5 pounds and it is not really an issue. I end up throwing 95% on the whisper for two reasons: 1) it is in a better spot (had it first) and 2) the wheel spins freely when the pedal is stopped. I find it really annoying to have the wheel stopped and not be able to spin it with the stewart.
  11. The kiln is just a standard catenary arch cross-draft kiln. the arch is one layer of hardbrick, about 3" of ceramic fiber, and then expanded metal sheets on top. The thin cement is a mix of fire clay, sand, and Portland cement, but I do not recall the exact mix. The cement is just thick enough to cover the expanded metal, probably 1/4 to 1/2" thick. I could try to get a photo, but it is just a solid gray coating - you cannot see the metal. My shed is 15' high, so it lets rain in at an angle and it has not shown any problems from moisture so far. The metal is just "expanded metal" available at any hardware store. It is commonly used in concrete applications.
  12. What would you like pictures of? Kiln? Saw? Happy to help, but may take a bit. I have not posted photos here before.
  13. I used a layer of expanded metal with a thin coating of a mortar with additional Portland cement added on top of the fiber. Has held up really well with little compression of the fiber. Try using a cheap circular saw (only $30 new) and 6" masonry disks (about $3). You can cut almost completely through on one pass. I have cut hundreds of bricks nd my cheap old saw is still working.
  14. I just got a great digital scale from Costco. There is no Costco in my area but I went to one recently while visiting some relatives. It was about $20 and seems to do an excellent job of weighing in grams all the way to about 20-25 pounds (almost the range you are looking for). I tried to find it online but it is not on their website. I just got it a couple weeks ago. I really liked that the battery area is well-sealed with 4 screws. My shop is very humid most of the year and I seem to only get about 2-3 years out of a scale once the humidity and heat get to the battery compartment and the batteries corrode the terminals to the point that the scale fails.
  15. MFP - I think what you are seeing as "darkening" is just the shadow of the hollow sections of the shelf. I have been using a few of these corelite shelves and they have held up well. Seem to warp less than the solid shelves at cone six. I just got a couple 1/2 round 26" advancer shelves and they are even better than I expected. Plan to order more once they get back in stock.
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