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RuthB

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About RuthB

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    Advanced Member

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  • Gender
    Female
  • Location
    Charleston, SC
  • Interests
    Clay, Glazes, Kilns, Firing, Marketing, Teaching

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  1. Babs

    Nice to read your words again RuthB

  2. Plates, platters, tiles can be stacked on edge leaning against the kiln wall, avoiding the element. Or a kiln post can be leaned first as a buffer. In this way, quite a few can be leaned, including leaning stacks against stacks Cracking problems are reduced as well. Check YouTube for some good videos on stacking flat pieces in this way all around the kiln wall, staggering stack against stack. Use the top shelf if post height is a issue. I stack anything that reasonably sits in or on top of another, bowls, mugs, etc. Three pieces max, unless it’s rim to rim or foot to foot. This guideline must have made its way into my DNA by now.
  3. I’ll make it this weekend and let you know when it’s up
  4. Plates can be subjected to a lot of stress during making that doesn’t show up until the firings. Plates that have been made by mostly flattening the clay with an outward motion are most susceptible to cracking, especially if they do not have a foot. There is a tremendous attraction between the clay and the metal wheel head and clay that has been stretched out against the wheel head will be subjected to competing forces. You’re moving the top part of the clay outward while the bottom is doing its best to stick to the wheel. Leaving enough clay to cut a foot on the bottom gets rid of the stressed clay. It also helps to move the hands back inward toward the center at least as much as you move them outward. Uneven drying can also cause cracking. Dry slowly, so that the rim does not dry before the center of the plate. A donut of plastic wrap around the rim will help. And make sure the plate is of even thickness. Thick and thin areas will dry unevenly. Slabs should be turned and flipped during the making to prevent similar cracking issues. Ruth Ballou
  5. Another option is to use a bulb syringe and a 1- 2” brush on the wheel. This technique allows large pieces to be glazed with a cup or so of glaze. The syringe is used to supply a continuous flow of glaze to the brush. Hold the filled syringe just behind the brush and gently and steadily squeeze it to supply the glaze to the brush as the wheel turns at slow to moderate speed. Too slow and the brush will not be able to evenly disperse the glaze. Too fast and you’ll encounter a dry brush with insufficient glaze to disperse. Do the back of the plate first, then flip and do the inside so that the rim will not be disturbed. I usually cost the rim first and then go inward. Refill the syringe as needed. Three passes is usually enough, but that depends on the thickness of the glaze.You can also add CMC to a couple of cups of glaze to make it brush-able.. CMC needs to be mixed with hot water in a blender before adding it to the glaze. Replace about 1/3 of the water with the CMC mixture. There are also a couple of commercially made brushing mediums, Spectrum Brushing Medium or APT II... though I have not used either of these. I can make a quick video of the syringe/brush technique if you’d like try it.
  6. RuthB

    Studio vacuums

    Thanks, Mark! This looks like a great system. In the past, I’ve used a cheap shop vac placed outside with a long pool hose duct taped to the unit. Not surprisingly, it doesn’t last long and is a pain to set up. Thanks for introducing me to cyclonic separators. Is the cyclonic separator the $99 DIY Oneida kit or the $1000 one? Thanks, again Ruth
  7. I am considering a couple of options for dust removal and cleaning. Is anyone familiar with the Dustless wet/dry HEPA vacuum? http://www.dustlesstools.com/dustlessvacuums/HEPAVacuums/hepa-vacuums.php. It’s advertised as being great for drywall dust. It looks to have some nice features. It will vacuum wet and dry without changing the setup and has a longer than usual very flexible hose. However, I cannot find any independent reviews. The second option would be a central vacuum type system with the unit installed outside the studio. I have a small one in the house, but would need a heftier unit for the studio. Any recomendations as to brand? Thanks, Ruth
  8. RuthB

    Getting zinged by bisque

    Hi Chris, I took a course with Curt Benzle this fall and learned a ton about working with thin colored clay. He leads a fantastic workshop. Problems with things falling apart are usually that the clay is either too wet or too dry when joining. Since you're having problems with delaminating, my guess is that it is too dry when applied, or not evenly wet and you've got wet and dry areas. How are you wetting the clay. Which side. How are you sealing them together. One idea that might help would be to place all the layers between two pieces of cotton sheeting and gently roll and flip them, and roll again. And you you might start a bit thicker than you want the finished product to be and roll it down to the final thickness. I'd love to know if this helps. Ruth
  9. RuthB

    Glaze Disaster

    Sounds like the soluble boron soaking into the bisque, melting very early, before the rest of the glaze ingredients have a chance and preventing adhesion of the glaze. See the above repost from Karl Platt..... Ruth
  10. RuthB

    Vintage Materials

    Pull the other one, guys! Nice try!
  11. RuthB

    Glaze Disaster

    Here's the post from Karl Platt on crawling and Gestley Borate Date: Mon, 4 Nov 1996 11:18:13 EST Reply-To: kplatt@glass.com Sender: Ceramic Arts Discussion List <CLAYART@LSV.UKY.EDU> From: "Karl P. Platt" <kplatt@glass.com> Organization: Glass.com Subject: My Crawling Glaze Has Ghastly Borate To: Multiple recipients of list CLAYART <CLAYART@LSV.UKY.EDU> ----------------------------Original message---------------------------- This glaze, posted here yesterday, was noted to crawl: Recipe: Percent Batch Nepheline Syenite 47.30 2365 Gerstley borate 27.00 1350 flint (325m) 20.30 1015 EPK 5.40 270 Totals: 100.00 % 5000 gm Also add: cobalt oxide 1.00 50 red iron oxide 2.00 100 rutile 4.00 200 cmc (mix dry powders well)0.15 8 The composition above bears little relation to : 61.61 % SiO2 14.23 % Al2O3 8.49 % B2O3 2.37 % K2O 6.55 % Na2O 6.72 % CaO 0.05 % MgO I get something that looks like this: Wt% Mol% KNa2O 7.37% 7.85% CaO 7.62% 8.99% CoO 1.04% 0.92% Al2O3 14.50% 9.40% B2O3 14.19% 13.40% Fe2O3 2.08% 0.86% SiO2 53.20% 58.59% I get numbers that look a lot different. For several of the raw materials actual analysis were used and for others, the table in Parmelee's book, which has never really failed me, are applied. Rutile, as it is a highly fugitive material was not included in the calculation. This is all to say that there are some descrepancies somewhere that need to be reconciled. The analysis furnished in the original post does not account for the coloring materials. This is not a good thing to do as these can and do profoundly affect the character of the glaze -- especially here where we're looking at 1% CoO and 2% Fe. Anyway, none of this has much to do with the cause of the crawling and that is the use of Ghastly Borate. Ditch the Ghastly Borate and your problems will vanish. Why? Well, once again, Ghastly Borate has lots of water soluble borate. When the glaze is applied to the ceramic, the borates are carried into the pores of the clay and ultimately form a film between the body and unfired glaze. This film, being rich in pure-ish borate, melts a lot lower than the glaze sitting on it. It thus melts well before the glaze and prevents adhesion of the glaze once it does melt -- it's a surface tension thing I don't want to go into now. The effect can be likened to water on a waxed car. There are also reasons why this effect is concentrated on rims, etc., which has to do with how the article dries after it is glazed -- and perhaps with how it was dried in the first place, but the core problem lies in the Ghastly Borate. The reason anyone bothered to invent frit was to solve problems like this a long time ago. Why on earth does anyone still use Ghastly Borate? Study a bit on frit and one will see that a foremost reason for employing frit is to render borates insoluble. >>if fired higher turns greener<< This is related to the presence of TiO2 KPP -- Who'll use Ghastly Borate only if civilization ends
  12. My main concerns with material storage are space constraints, ease of access and moving things around. I just got a different IKEA container that seems to work well. Two fit on a furniture dolly from Harbor Freight, topped with a piece of plywood. In the pic there are three other wheeled containers that I found on Amazon. They're ok, but I think the IKEA ones have a smaller foot print and fit in closer together. The dolly goes under the table on its short side; I can get 2 in the space of one of the others. I don't transfer bags to the container, either, because of time and dust concerns. Instead, a large garbage bag goes in the bin first, then the bag of material, which I cut open after it is the bin. I used to use the stackable containers and found that they do sag and it's difficult to get full bags in. Everything has to be unstacked to load a new bag. Smaller amounts are in stackable containers on another wheeled shelving unit. The bin labels are placed in those plastic sleeves for packing lists. I don't fully attached the sleeve; one end is left open so I can change the label if needed. Same labeling system on my glaze buckets. I also put a card in the bins. Too many labels have fallen off, gotten wet, rubbed off, etc. over the years. I made the wheeled glaze table that the bins are under. There is a 6" deep shelf level with the table to hold frequently used items. Keeps them off the general work surface and I can move the table easily for cleaning and glazing. It only took 20+ years to figure out. But then I'm a fast learner.... Ruth
  13. RuthB

    Vintage Materials

    I wood fired a lot in the 90's... hence the Avery. Yes, I am well aware of its value! My current kiln was built as a wood/gas kiln. It's been wood fired twice. First time the chimney was too short. Second time, the chimney was too tall. Third time, hopefully we'll hit the Goldlilocks spot. Some of the Avery will go in this firing. After that, the kiln will be fired with gas.... ^10. I also have electric, for ^6 or ^9 ox... A potter can never have too many kilns, eh? I'm not looking to use these in my existing glazes... I'm well versed in glaze calc and the software. I'm really looking for those "lost" glazes... the gorgeous spods, the "if only that old spar was still around" glaze, etc. Clinchfield will go to some Celadons, but I was wondering if there was something else special that anyone remembers. I'll keep y'all posted with results... Ruth
  14. I have several pounds of some "classic" materials that are no longer available, at least in these vintages. The supply dates from the 90's, 80's and earlier. There's at least 25 pounds of each. Cornwall Stone, Spodumene (Foote), Clinchfield Spar ( a high Pot Spar from 1960!) and Avery Kaolin. I've been hanging on to them, thinking about the best way to use them up. Then, I thought... why not ask some other long time potters! Any suggestions of classic recipes that used to work that didn't survive one of these material's changes? Complimentary tea bowl with your glaze as a thank you for your suggestion. Ruth Ballou
  15. RuthB

    Glaze Disaster

    Questions, questions, questions! I've known Ghastly Borate to sputter, even in low amounts in a glaze, but not calcium frits.... Even with one that I've used a lot that is 90% Frit, frequently loaded right into the kiln. Have I just been lucky? I would be surprised, because if it can go wrong, it has. Perhaps mistakenly, I considered that sputtering was one of the main issues of Ghastly Borate and reason enough to avoid it. Somewhere on the hard drive, I have a post from the 90's by Karl Platt all about the bad behavior of GB. I will try to find it. R
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