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Everything posted by fergusonjeff

  1. Thanks for the photos Min. I was not following the text description and assumed it was much more complicated.
  2. fergusonjeff


    I am pretty sure most cone 6 speckled clays (especially Laguna's speckled buff WC-403) use granular manganese for the dark speckles, not ilmenite. The speckles bled well into most glazes. I mix together a lot of different cone 6 clays but usually include 50% speckled buff for the speckles.
  3. If you really need to determine the volume of leather-hard or even bisque-ware use something other than water (rice, beans, sugar, sand...)
  4. fergusonjeff

    Firing with glass

    Just a quick side note. Glass does not still move at normal temperatures. This myth relates to old windows. Many really old windows were made from blown glass that was flattened while hot and then cut to shape. This often resulted in uneven thickness. The glass was usually installed with the thicker sides on the bottom. More recent (but still old) glass has a very "wavy" look and this was also from the initial manufacture, not continued movement after installation. If glass was still moving, we would see some slumping in glass forms thousands of years old from many places in the old world. Unless they are exposed to enough heat to start melting they do not move. As an archaeologist I work with lots of volcanic glass (obsidian) artifacts. There are many artifacts millions of years old, and aside from some surface weathering (usually a function of a slow hydration process) there is never any change to the overall shape even after hundreds of times more time than the old blown glass windows. The incompatibilities between glass and clay are a function of slight differences in expansion related to temperature change, not continued flow in the glass.
  5. fergusonjeff

    Cone 5 vs cone 6?

    Even with the higher voltage elements this kiln is not ideal for cone 6 firing. I have the same kiln and only get about 20 bisque (^04) and maybe 30 glaze (^6) firings on a set of elements. I thought it was a fluke the first time, but I am just about to replace them for the second time and got almost exactly the same number of firings. For a casual potter this is a lot of firings (many years), but not great for higher production. I am planning to order a new L&L e-quad kiln very soon to get some longer life.
  6. fergusonjeff


    I use a Whisper every day. It has decent power for most throwing (everything from mugs to large platters). It is possible to slow it down at times, but it is rarely a limitation. The quietness is great and I really like the free-spinning wheel head when the pedal is up. I have used it daily for 6 years now without the slightest problem. I recently decided I needed a second wheel and purchased a high-end Skutt (Thomas Stuart) wheel. This certainly has more power but I can't say it has allowed me to do anything the Whisper did not. The Skutt is really loud by comparison. I thought I would really like the extra power, but I still use the Whisper for about 90% of my throwing.
  7. The idea of only keeping the best stuff is an interesting one. As an archaeologist (my day job) who studies craft production in the archaeological record I am always interested in what evidence for learning and experimentation survives. Aside from the academic pursuits, there is value for the potter in working through the whole process, even if the early steps are not perfect. If you spend years perfecting throwing you will produce great pots with no ability to trim. By the time you learn to trim, you will have to work through drying and attachments/modifications. Then there are years to perfect firing and glazing. At some point you also have to work through the skills needed to market and sell your work. By working through the whole process from early on there is the potential to learn many steps of the process simultaneously. There is certainly value to training on certain parts of the process individually, but it is important to remember that making and selling pottery is a massively complex endeavor with many independent components. Getting good at just one part does not necessarily move you toward a final goal.
  8. fergusonjeff

    Flashing Slips

    I apply flashing sips to bisque pieces. I use a few different slips on bisque. They are typically about 1/4 epk, 1/4 high-iron clay (like Helmar), and up to 1/2 Neph Sy. I have pushed the Neph Sy up to 60% and then it is acting more like a glaze (which I really like). My firings are typically only about 14 hours, so on the shorter side. Even though I go over cone 10, the extra Neph Sy helps to melt the surface in the shorter firing.
  9. fergusonjeff

    Woodfiring Clay Bodies

    It is likely that the color is coming from a flashing slip. I can get very dark areas (not sure about purple though) with high-iron flashing slips in longer firings. In this case the particular clay color is not as important. I do use a couple darker clays (mixed, not commercial) that will get nice dark browns on their own. A picture will definitely help.
  10. fergusonjeff

    Best Tent For Craft Show?

    GEP, thanks for the info. I am about 6'4" and in decent shape, so I am not too worried about set-up. Just looked at the light dome. It is a pipe construction which I think makes much more sense than the expansion style like the EZ-ups. How does your tent do in the wind? With the awning, stabilizer bars, and shipping, the Trimline is almost $1400. The Light Dome is a few hundred cheaper.
  11. fergusonjeff

    Best Tent For Craft Show?

    I should add that I do my shows in the summer in the Midwest, so that means lots of thunderstorms and high winds. Does anyone have experience with the Trimline tents? I would rather spend the money once on a good tent than deal with repairs. One tent cashing could damage thousands of dollars in pottery.
  12. fergusonjeff

    Best Tent For Craft Show?

    Hoping to get an update from Neil on the tent he ordered. I need to move on from the very fragile EZ-Up tents. A friend recently ordered this tent, but it does not look like much more than the EZ-up but more than twice the price: http://www.eurmax.com/beyond-10x10-instant-canopy-with-enclosure-walls.html Does anyone have any experience with the Eurmax Beynd tents? Thanks, Jeff
  13. fergusonjeff

    Peter Pugger VPM 20SS

    The maximum pugging rates (pounds/hour) seem kind of useless. If all you are doing is throwing in clay and spitting it out as fast as possible then what is the point? I use mine for mixing different clays, adding stuff to clays, remixing trimmings/reclaim, mixing up clay from dry ingredients... All of these require mixing time. I mix while doing other tasks, so no time lost.
  14. It will work better with more absorbent bats. Plaster works very well, but I have not tried it with any wood bats.
  15. After 3 years of using my batmate just an Min described, I bought a new one. Of course I cannot find it now, so I just bought a large synthetic chamois at the hardware store. Half the cost of a batmate and I cut out 2 12" circles and had lots of scrap. Works just as well as the batmate for the first few weeks so far. I use it entirely with plaster bats ranging from 7 to 12". I have to re-wet the batmate a little each time, but I just throw some water on with a sponge.
  16. fergusonjeff

    Peter Pugger VPM 20SS

    As to the spiral cracking, I don't think it is related to the spiral nature of the pugged clay. I cut the pugs, make balls and don't worry about direction. On the few occasions of a spiral crack I can usually trace it back to poor trimming. The vacuum on the 20SS (and regular 20) works on the rear chamber. There is a very small gap around the shaft that allows the air from the front (clay) chamber to escape to the vacuum pump in the rear chamber. When mixing, you are bushing the clay against the back of the from chamber where it seems to prevent the air from escaping into the rear chamber. By switching the machine into pug mode you are moving clay away from the wall separating the chambers and this usually breaks the seal. I first saw this on a youtube video and I think this is the one: This is not my video, but it shows the switching process somewhere in there.
  17. fergusonjeff

    Peter Pugger VPM 20SS

    I have the VPM-20SS and really love it. There have been a few threads on peter puggers in the past that would be worth searching for. In general it does just what they say. I would not be so sure it could handle 25#loads. The hopper seems to mix best when it is completely full. I usually add about 30# per load and there is usually about 5-10 pounds that remain inside. I switch clays all the time and as long as I don't minds the clays mixing I don't worry about it. There is a fair amount of clay that remains in the nose and will spiral into the new batch. The stuff remaining in the chamber will mix will, but the stuff in the nose will unevenly mix throughout the entire pugging. When switching clays I usually run it through twice. Every few months I switch between Cone 6 and cone 10 clays. When I do this I clean it out as much as possibly without taking it apart. A few percent of the wrong cone won't make too much difference. If you were switching from a dark stoneware to a fine porcelain and wanted to keep it perfectly white then you would have to take it apart are really clean it. Fortunately I am not that picky. I use it a lot for mixing both scrap and for mixing entirely new batches from powder. Adding water to scrap and mixing from powder both take a little practice. The whole batch tends to like to spin when a wet layer lubricates the outside of the clay. Sometimes this can resolve itself with just a few minutes of mixing, other times it requires some fussing. I have not had any problems with inconsistent moisture. I tend to occasionally throw in a bucket of mixed scrap. The scrap will vary from bone dry to leather hard. In general this is not advised because leather hard clay does not break down easily. I usually mix a load as soon as I empty it that way I can mix the new batch for a few minutes, let it sit overnight, and then mix the batch again the next day before pugging. If you tried to mix scrap of varying dryness and pug right away you will probably have harder chunks in the pugs. One final piece of advise involves getting the vacuum to move into the chamber. When you start vacuuming you are usually only working in the rear chamber. I usually have to start pugging slowly until the seal breaks between the two chambers and them put back to mix. The amount leaving the nose will suck back in and then the vacuum works in both chambers. I can tend to pix a lot of clay from scratch and it is not the easiest. I still really like the 20SS, but if I ever come across a reasonably priced solder mixer I might get it just to make it a little more efficient. But, for mixing wet clays and reworking scrap it is excellent. This is definitely the best addition I have made to my studio. I was reluctant give the price (~5,000) but it has been even better than I expected. I never use clay straight from a bag anymore. I can pug a load to whatever moisture level I want for that day's items. I always struggled with this when using clay straight from bags. I think I addressed most of your questions (plus some). If you have other please let me know.
  18. fergusonjeff

    Raku Rocket - Kiln #3 by Ian Gregory

    I built my raku kiln using welded wire (1/2" I think). Since it is on the outside of the ceramic fiber it is holding up just fine. It is sold in rolls and is not very expensive. The 1/2 x 1/2" mesh is often used to build small animal (rabbit) cages.
  19. fergusonjeff

    pieces warping during glaze firing

    I had lots of cone 6 issues with warping (both thrown and slab pieces) a few years ago. Increasing the thickness helped a little and so did flipping the slab more while rolling out. But what made the biggest difference was adding about 5-10 % fireclay and fine white sand. I add a couple pounds of each to a ~35# pug mill load. Without a pug mill it could be wedged in but might not be worth the trouble.
  20. fergusonjeff

    Advancer Kiln Shelves

    Yes thanks for the info on warping at cone 6. I am about half way through replacing the standard 1” shelves with corelites and not getting any warping yet. I guess I will just go the rest of the way with corelites. I am not too concerned about the space saving. I can buy about 4 or 5 corelites for the price of one advancer. Buying shelves is about as fun as buying car tires. Nothing new or interesting, just back to about where you started. It was certainly a shock buying a full set of silicon carbide shelves for the wood kiln. I really hope they hold up.
  21. fergusonjeff

    Advancer Kiln Shelves

    I have been looking into shelf options for my electric kiln. I have had lots of warping on my 26" half round standard 1" thick shelves fired to cone 6. I have added a few corelite shelves and these seem much less prone to warping, but are still fairly thick. The ~$225 price per half shelf for advancers (from kilnshelf.com) is not a viable option. Axner sells a 26" half round "nitrile-bonded" shelf that seems very much like Advancers. They are 1/2" think. But the Axner price in only around $80/shelf. Can anyone tell me the difference between the Axner shelves and Advancers. I called kilnshelf.com but the technical person cannot call me back until at least Monday. thanks, Jeff
  22. fergusonjeff

    Plaster Vs. Bisque Bats And Molds

    I just use a thin wipe of Vaseline on metal and wood forms. I use Plexiglas for the working surfaces and it pops right off the Plexiglas.
  23. fergusonjeff

    wheel movement

    I currently have a Shimpo Whisper and really like the wheel. The only limitation has been slowing down with even just a few pounds (not a really big problem). I really like that when the wheel is stopped (not necessarily turned off) the wheel head spins freely like a banding wheel. I end up using this a lot to spin the piece for texturing or just to remove bats and many other tasks. This is one of the only electric wheels I have used and I am thinking this is not a common feature. I tried spinning a few other wheels and they do not spin easily. Are there other wheels available that have this free-spinning feature? Thanks, Jeff
  24. fergusonjeff

    wheel movement

    Neil. What are your thoughts on the ssx drive?
  25. fergusonjeff

    wheel movement

    Neil, thanks for the chart. I am contemplating a new wheel. Based on the torque numbers why would anyone bother with the more than 1/3 hp Thomas Stuart?

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