Hulk

Drop and hold seems to be working/helping in glaze fires for me as well. I'm also holding in bisque fire, ~1500°F for an hour, powered kiln vent on throughout, which also seems to help. "Seems" on account of variables, aye. Some of the clays I've tried are a bit more sensitive to too much heatwork; some are very sensitive to too much heatwork.

Commercial glazes, err, some commercial glazes may contain less expensive ingredients and/or behave poorly. Less behaved glazes may: settle quickly, crawl, craze, pinhole ...have washed out color (especially where expensive colorants are involved) ... etc. When looking for recipes, starting out*, a few ideas (which I'd found here, in this Forum, and a few other places**) were helpful: from a reputable source; with helpful notes on application, durability, and heavy metal leach testing results; with pictures! I just picked several recipes, made a materials list, and went shopping***! From there, learned, err, learning from successes, failures/mistakes, and more reading. ...and thanks to several Forum regulars for insight and assistance. *Coming up on six years ago, how time flies **Digitalfire.com, a trove of information; the glaze recipe book at local JC ceramic lab (we were using the glazes - direct experience!); Petersen's book The Craft and Art of Clay; Van Gilder's book Wheel-Thrown Pottery; and several other books, magazines, and web pages. Oh, web pages! ...Hesselberth's website can still be found, FrogPondPottery, Tested Glazes | Frog Pond Pottery (archive.org) Lakeside Pottery also has glazes sub-pages with pictures and notes... ***took the pickup truck, packed the load up against the front of the bed and tied it down tight, some twelve hundred pounds of clays and glaze materials...

I'm using petalite in my liner glaze*, which was a study in craze control. Spodumene has more lithium per unit weight, but petalite was more competitive in lithium per unit co$t, with side benefit of avoiding the reported foaming/rinsing. *was, on account of petalite costs have gone up so much! I'll be re-visiting my liner glaze formula soon, very ...I have enough petalite to last a year or two.

"...do you staple/glue/tape the paper to the board? Does it last very long?" I'm folding the shelf paper over the edges and stapling to hold the edges down. The shelf paper has a removable backing that reveals a sticky side; the side that shows is shiny. I needed ware board - smooth, for freshly trimmed feet! I'm not doing any work on the shelf paper surface, just setting down and picking up pots; they don't show any wear yet, but it hasn't been terribly long either.

With a base shelf and half inch risers underneath it, you'd be down to 25.5" to start (given 1" shelf). My experience* says leave a smidge of room for expansion. Although everything gets hot and therefore expands, perhaps not all at the same rate, so leave a quarter inch, at least? Mainly to avoid touching and therefore melting together, also a) extra space between wares and the elements to reduce any spitting of bits/droplets onto the elements, and b) extra space between wares where reducing fuming** is a concern. Use a tape measure or ruler to get the available space. If you're throwing/making to the available vertical, the subsequent clay shrinkage should leave plenty of wiggle room... Check back later for more input from other Forum members! *I'm typically firing three to five levels in my 27" kiln. Sometimes I leave just a quarter inch from top of the ware to the next shelf (or the lid); so far, a-ok. **I like how my red glaze picks up some blue/cobalt. The chrome seems to get around as well.

I'm also using tile backer board for wedging surface - one each for red, buff/brown/black and red clays. It's easy to clean, lightweight, the clay doesn't stick (much). Plaster slabs and bats are handy for drying - clay to be worked, wares to be trimmed, and freshly trimmed wares as well. For ware board, wafer board scraps with the one smooth side, wafer board with shelf paper on one side, and particle board with shelf paper on one side.

Hi Carol, welcome to the Forum! By strange torque, I wonder if what you are experiencing is the clay sliding on the bat? Of the several bat materials I've tried, the black plastic ones seem to offer the weakest grip for the clay. If that's it, going a bit wider on the centered part, and going easy might help? As the bats got scratched, well, the shiny wore off, that seemed to help too.

Practice on toss-away bits afore turning to the ware(s) to be saved might be time well spent...

Weighting that ceramic handle might encourage the tool to land handle down, then the handle shatters, absorbing enough energy that the precious tool bit survives (vs. bounce, bounce, break!)? I like it. See also search results for "wood tool handle" or "file handle" or "wooden tool handle" ... I like the "hook" shape, it's closer to what I use

Caliper tool that indicates thickness at the other end (double ended calipers*), it's a something I wanted/needed for some time now, for I have poor judgment of thickness past the reach of thumb and first two fingers. That middle one looks handy for wares the left one doesn't fit. I like the thumbtack idea Min! *There are many options "out there" - try "double ended calipers" also turners/turning/bowl/bowl turners caliper(s)

Almost 6.5 years in, I'm still sayin' retirement can be good-oh. ...important it is, imo, to stay vitally engaged (aka "busy")!

With the image you might yet get some more information/ideas, please do check back Griffith. Added: If not trapped moisture flashing to steam ->boom, then some bits/particles off-gassing whose escape route is progressively closed off as the clay sinters? Curious, looks like a large flake, and given the uniform thickness of a pencil, also curious how a large piece has come off and no damage to the interior? ...almost like there was a layer, like a pastry, or crust, that flakes as it bakes.

Interesting! Griffith, looks like there's a milky translucent white shiny coating on the clay within the defect area. Oops, that is glazed; the chip blew out in the bisque fire, per your first post. Is the pot thickest where the defect occurred, and if so, how thick? The long preheat should eliminate water to steam as the cause, however, depends on how damp it was going in, how hot and long the drying phase.

Unstretched, de-stretched, aligned, reprogrammed, I like all of them! I like this also: "The compression is not to dewater or make the clay more dense. It is to alter the residual stress state of the clay. To reprogram its memory, so to speak." - Gavin Stairs (on potters.org) Richard Burkett's shrinkage test, same thread, demonstrates the (dramatic) difference "compression" makes - overall shrinkage 15% for stretched slab, 11% for compressed slab, 12% for "normal" slab - big difference. If pushing on the clay - against the wheel head as it revolves, but not so much that the thickness is substantially changed* - alters the density by squeezing out water, I should be able to easily squeeze water out of clay? How? I haven't any luck with that, but I haven't tried applying progressive test to discover the force required to squeeze water from clays quickly, as in the amount of time one spends compressing the base of a wheel thrown ware... *where a ridge of clay moved one way is then reversed.

Hi Mudfish1, Sorry about the delay getting your 2nd post (above) approved. Forum Administration and Moderators are testing an edit to new member registration, which should reduce (perhaps eliminate) the Spam posted here. We ran #6 wire for new 48 amp kiln, a bit less than fifty feet from breaker to the fuse box by the kiln. The specs call for a 60 amp breaker, #6 wire. The difference - typical periodic loads vs. ceramic kiln - may have to do with "continuous load" - where the kiln is drawing the full 48 amps for extended periods. Please check back for updates from device/electrical authorities.

Thanks Bill, thanks Jeff. I interpreted overwork as forcing the clay enough past its limit of elasticity, which I'd called shear or partial shear. For Bill, excessive trimming/burnishing. For Jeff, extended throwing time, where many passes, wet the whole time, leads to over-wet issues. From my pov, each a legit concern! In my experience, some clays tolerate more wet time than others. I do like to rib away the slip on the outside of forms, and sponge away most of the slip/wet from the insides as well. "Wetting" the clay from the outside is arrested soon as the second pass with the metal rib is complete, which is part of my process now - when wetting ceases, drying begins! A form that may not be prime for flaring out - too wet - can be ready not long after said ribbing. Clay responds to pressure, pressure and movement, imo. Where the clay is damp enough to move, trimming and ribbing/burnishing does move the clay, agreed. The clay moves, round and around. Burnishing definitely involves movement; smearing might be a good word, but it doesn't sound particularly good. Where the smear begins to separate later on, ah! I don't see where clay volume is reduced by applying pressure, nor where moisture can be squeezed out by applying pressure to clay on the wheel (in a clay filter press, well, that's different, eh?), so the term "compression" I still don't like, but am mostly over it, heh.

Jeff, Bill, Curious what "overwork" means, exactly? I'm not recalling hearing/reading what is overwork in general, nor overwork specific to throwing forms. Is it where the clay has been pushed to the point of shearing? I'd observed, early on, that clay doesn't seem to recover well from being pushed to the point of shearing - best to remove, rewedge (thoroughly), then start over, which I'd classed with the more common problem, a) bubble, blob, dry or wet spot - any inconsistency - can cause the clay to flow unevenly, and somewhat less common b) where the clay moves on the bat, as problems that regularly occur on my wheel and on the others around me (Wheel I and Wheel II classes), but not discussed much. ...my thought was, why not experience these on purpose and thereby learn to recognize? Push until the clay either shears or disengages from the bat; repeat until both are clearly achieved. Put a few BBs (small, round, smooth - no sense getting hurt) in the clay, throw; try again with a soft bit of clay folded in; try again with a stiff bit folded in. ...ok, now don't do that/them.

Hi Beccap, welcome to the Forum. My guess would be that harmful exposure would be accompanied by some coughing - and other symptoms/indications; however, lower level/chronic exposure over time definitely creeps up stealthily, see CDC articles here: Crystalline Silica | NIOSH | CDC As for your questions, they are (my opinion) good questions, which you might pose to your health care provider at next opportunity. Meanwhile, keep up the good practices.

see Mark's post: Replacing potentiometer inside Brent pedal - Page 2 - Equipment Use and Repair - Ceramic Arts Daily Community

Hi HenryCalvin, Welcome to the Forum! Ceramic clay is typically divided into categories by firing temperature. The lowest firing clays (low fire, earthenware) require 1500°F or more, which glows orange red (very hot!). Options for working at lower temperatures and/or no heat work required, I'm not familiar with. While waiting on more feedback, look into "air dry" clay - there are several. Here's an article discussing some of the options: The Best Air Dry Clays for Artists | Susie Benes

Hi Virginia Murphy Pottery, welcome to the Forum! Hard to tell if the craters, smaller pits, or both are open all the way to the clay? Second question, are you seeing any pattern? ...looks like all three pitted/crater pieces have more defects up/away from the foot. If the glaze layer is consistent, maybe the thicker portions didn't pit/crater as much? The last ware, with the red glaze, that came out well? My first guess would be drop and hold*, as Bill mentioned. Here's a Tony Hansen article on the subject: Pinholing (digitalfire.com) Dropping 100°F and then holding for a half hour or more has really helped with multiple issues in my Studio...

"Which do I use ?" Hard to say. I'm guessing the larger the container - the larger the mass of glaze - the longer it would spin before stopping, everything else being equal - perhaps due to more mass per unit surface area of the bucket interior, which provides the drag? Easy enough to test; mix thoroughly, pour some off to a smaller bucket, re-test. My experience is with different glazes and two gallon buckets. However, I've good results with tweaking the specific gravity and thixotropy of every glaze I've tried. Two of my glazes I don't add any Epsom salt too at all; they gel great as is. Added: 21 liters is just over 5.5 gallons, that's a lot of glaze

Good idea to start with a test batch! Did the Epsom salt addition make any difference at all? My glazes, some require more Epsom salt (saturated) solution than others. A few points in specific gravity can make a difference; I run as low as 1.41 (one glaze), high as 1.46... ...after an addition, stir, stir, wait, test, then give it some time before making another addition. How to measure the "gel" - when has enough Epsom salt been added? See Tony Hansen's video clip: Thixotropy and How to Gel a Ceramic Glaze (digitalfire.com) ...stir the glaze at a repeatable and reasonable speed, then watch as the revolving mass slows and comes to a stop. I look for three to four turns before the entire mass slows to a stop, then "bounces back" just a little bit. Glaze that requires adjustments just keeps on spinning well past three or four turns, with currents of different speeds shearing against each other. For pouring and dipping, slow and deliberate motion, particularly pouring out or lifting up. A bit wetter glaze (lower specific gravity) allows more time to complete the glazing, but takes longer to dry. Hope that helps, check back for more suggestions from others, and please do update on how it goes...

Hi MaryMen, welcome to the Forum! Which model? Looks like current (manual) models have wheel type cranks except the "22 inch Mini Might II" and "SRT-18" which are fitted with crank arms. If it's not possible to find an off the shelf item, adapting something looks to be straightforward. I'm not finding a detailed image/drawing depicting the handle attachment to the shaft for either model. Can you provide a close-up image of the handle attachment, the shaft diameter, and type? The SRT-18, looks like a round shaft that the handle fits over, fixed by a pin. ...how large a diameter is required - how big a handle? McMaster-Carr has a beautiful polished three spoke aluminum wheel, fourteen-inch diameter, item 6022K21 - it's expensive. They've a twelve-inch spoked dull iron wheel for less than a hundred US dollars, 6025K22 There are round, round and keyed, threaded, square, and "blank" attachment. The blank ones, machine to fit the application. Winco has a 11.8" wheel, just under a hundred bucks. Reid Supply lists several handwheels. Fixtureworks Rencol Added: tried contacting Bailey for an alternate crank?

Hi Babs, No haven't tried Lakeside Pottery Clear Blue w/o CMC. Not sure why it's included; the notes don't mention anything about it. Next time mixing some up, I'll pour off some and withhold its CMC to do a side by side. My guess is the CMC is for keeping it stuck on. This blue is one of the recipes I'd selected when first making up a list of materials for glazes - was driving the truck to the big city, so. Any road, this blue and the red I use are somewhat translucent; I really like them.