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Min

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  1. Take some of the same clay and make some circles just slightly smaller than the base diameter of the mugs and about 1/4" thick and dry them between boards so they stay flat. Bisque fire them then set mugs on the bisqued circles of clay. If your glaze is fairly stiff this should work, if it's runny then you're going to have to grind off glaze drips. If you cut more of an undercut at the base of the mug you don't really see much raw clay at all.
  2. I really doubt the clay I used would be available to you, F78G from Plainsman Clay in Alberta. Haven't used any clays from Armadillo and don't know if they are an option for you but their Buffalo Wallow looks like it could be tight enough with a posted porosity of 1.73 There should be someone on the forums who knows about their clays and/or other ones in your area. I would look for low porosity figures, some sand or grog for strength, the colour of the fired clay. I would just buy a bag to start with and run your own porosity and absorption tests on it before making the pot. Compress the clay slabs with a rib to push any grog or sand into the clay. If the unglazed clay is too rough you can sieve some slip made from the same clay and right after rolling and compressing the slabs brush a couple coats of slip on the slab.
  3. Is this going to be a rectangular bonsai pot? If so it wouldn't be difficult to make from slabs. I've made a few really big planters this way. Thick slabs, like 3/4" thick made from a super coarse clay, let them stiffen up then miter the joins and slip / score. No molds or forms or special equipment needed.
  4. No problem Chris, I enjoy playing around with glaze calc, it’s kind of like doing a crossword puzzle. My version is probably going to melt earlier than yours as I used some frit. Since frits have already been melted once they melt sooner in a glaze than supplying the same ingredients from raw materials. My version also might be a bit more fluid than yours because of the frits. You look at recipes on an oxide level (that little box in the lower right corner of my screenshot above), apart from the changes in sodium and potassium our formulas are the same. I thought your original recipe was way too high in custer. If you have a recipe really high in custer then the alumina it’s supplying is going to be high also, that means there won’t be much room for clay in the recipe. If you don’t have any clay in the recipe there can be issues with slurry suspension in the bucket, settling and hard-panning, and drips when dipping. Also found it odd that on the one hand there is a high amount of sodium and potassium (makes for increasing expansion figures in a glaze) and then it looks like the lithium and zinc are in there to try and bring it back down a bit. Are you totally committed to this glaze or are you open to another one? I’m hesitant to just pass along recipes since this one has a fairly high COE, if you are using it as a liner then I’m guessing your other glazes are high COE also? If you have another gloss recipe that you use on the outside of the pots you use this liner with we can have a look at the COE figure and see how they compare. Do you get any crazing with this glaze and any chance you have run crazing stress tests with it? (BTW Fusion frits are available from Georgies on the west coast if you can’t find them by you)
  5. Application.jpg

    @Farid, just wondering if you had a comment or question about your glaze blisters in this photo? Didn't see any other posts regarding the glaze problem.
  6. Why not underfire clay

    By firing ^6 clay only to bisque temperatures it is going to be open and very porous. Bisque temps are meant to leave the clay in this state so the glaze will adhere to the pot. If your glaze has any crazing or micro fissures whatsoever or the pot is unglazed on the bottom the pot will take water into the clay body itself. Doing the washing up or using the dishwasher will introduce water into the clay, now put that pot in the microwave and you’ll feel the pot itself getting very hot from the absorbed water in the clay. This might take a little while to happen but it will happen. Absorbed water in a pot will in turn cause crazing of the glaze in and can grow mold. Added to this is ^6 bisque isn’t going to be as strong as ^6 clay fired to maturity. Yes, low fire clay is porous, with the exception of fritware, but the clay is fired to maturity, it’s not vitreous but it’s matured. edit: if you have a piece of your current clay that is bisqued but not glazed try filling it with water and leaving it on a piece of newsprint for a couple days. This is a simple test for clay that is to be used for functional pots, the pot shouldn't leak even without glaze. Guessing the paper will be quite damp and wrinkled with this test with your ^6 clay fired to 04
  7. Why not underfire clay

    For functional pots I wouldn't use ^6 clay fired only to ^04 anymore than I would use ^10 clay fired to ^6.
  8. You can supply the lithium from a frit to (mostly) avoid getting the crystals if they get to be a nuisance. I played with your recipe over lunch, reduced the custer by over half to get some clay in the recipe, could leave the talc out altogether as it’s not going to be doing much. Sodium and potassium amounts are more or less reversed, supplied mostly from the custer and 3110. Other fluxes remain the same, as does the alumina and silica. Should behave better in the bucket and application, probably wouldn’t need to add bentonite. Expansion is tiny bit lower but still really high as it is in your recipe. (your recipe is glaze #1, my version of it is #2)
  9. Most of my wood batts are MDF 5/8" thick, couple thoughts come to mind. The Batmate might be a bit too damp and / or wondering if your batts are new? Don't know if there could be some kind of finish on the MDF?
  10. Peter Pugger VPM 20SS

    The literature from Peter Pugger states the VPM 20 has a capacity of 45 lbs and can pug at a rate of 600 lbs / hour and mix at 180 lbs/hour. VPM 9 has a capacity of 25 lbs and can pug at a rate of 500 lbs / hr and mix at 150 lbs/hr. If the quality of the pugged clay is comparable the mixing and pugging rate seems more relevant than the capacity. Just for comparison the Bailey MSV 25 with a capacity of 25 lbs pugs at a rate of 900 lbs / hr.
  11. Peter Pugger VPM 20SS

    I get what you are saying but I do exactly that with the Bailey Mixer Pugger with vacuum. Put hard chunks of bone dry, slop, leatherhard and use the mix function until it resembles dryish sand then add water, let it slake for 5 minutes or so then blend and pug. It's good to throw right from the machine without letting it sit. Yes, if I let the pugs sit for a day or two they do stiffen up a bit from the clay absorbing more of the water but my experience with using it for quite a few years is the clay is perfectly throwable straight away.
  12. I'ld take that foam flooring out all together and put down some sheet flooring that you can wet mop. Have a pair of shoes that stay in your workroom so you don't track dust through the house. Also, if you can use that ceiling fan somewhere else in your house I'ld take it out since you're not going to want to have it blowing dust around.
  13. Buying clay for first time

    I would use Plasticine. It's inexpensive at a dollar store, doesn't dry out quickly, won't shrink, can work fine details into it etc.
  14. Glazing interior of cruets

    Some does and some doesn't. Manufacturer might give you absorption figures but for more accuracy you need to do some absorption tests on your clay fired in your conditions. About 3/4 of the way down this article it explains how to go about measuring absorption. For an oil bottle you are going to need the absorption to be as close to zero as possible. For cleanliness I would continue glazing the insides. Welcome to the forums
  15. I did try one but it really didn't work, I put it through the wash thinking there might be sizing on it but didn't help. Batts kept coming loose. Nothing worse than having loose batts flying around. Guess there are different qualities of synthetic chamois.
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