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Chris Throws Pots

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Posts posted by Chris Throws Pots

  1. Hi Plum,

    I'd like to add one other thought to the conversation, as I recently found myself with an entire kiln's worth of work badly bloated and had to go through the process of diagnosing the cause.

    As many have already stated the two major causes of bloating are insufficient burnout of organics during bisque and overfiring. What I discovered was that I was overfiring, but  wI was oblivious to it. The calibration of my thermocouple had drifted due to corrosion on the wires that connect the TC to the controller. Essentially my kiln thought it was firing its normal ^6 medium speed program, but it was really firing a hard ^8. The thermocouple was telling the controller that the kiln was the equivalent of two cones colder than where it actually was, so all my work was getting scorched and bloated. 

    Hopefully this is not your issue. Hopefully you're firing with cones either in a sitter or as a check on the controller's/TC's accuracy. But if not, include cones in your firing to make sure the ^6 you're intending to fire to is actually the heat work you're achieving. My understanding is that the Standard 266 really can't handle overfiring/refiring without bloating. So making sure your kiln isn't overfiring will be helpful in figuring out how to best proceed with clearing up your bloating issue.

  2. Thanks Lee, Neil and yappystudent for your thoughts, but I don't think I explained my question well. Our studio already has the walls lined with boltless/rivet style shelves for members and students to put their work in progress, clay, personal tools, etc. I'm talking about when you make a piece on the wheel and wire it off, where do you put it then, in the moment so you can move onto the next piece without getting up?

    Below is a picture of the current setup. While throwing, people land wareboards and bats on the tables that sit in the middle of the wheels. Then later, when they clean up to leave the studio, they wrap their work and store it on their personal shelf.


    When people are seated at the wheels it's a tight squeeze between the wheels and the shelving units. I'd like to rebuild the two central tables that the wheels are positioned around so that they are both narrower and hold more. Vertical is the way to go, I just haven't figured out what will work better than what we have without obstructing students' view of their instructor at the wheel on the end.

  3. For those who run or work out of community studios: What shelving/counter top space is available to place freshly thrown pots on bats and ware boards?

    About  year ago the community studio I manage moved from one location to another. Last year's budget limited us to moving all our existing equipment and setting up in the new building, without purchasing/building anything specific to the new space. Now that we're into a new fiscal year I have some available funds to make improvements. The facility is much better overall, but one of the quirks is that the wheel room, though comparable in square footage, is narrower than where we'd been.

    Our (14) wheels are set up in the center of the room around a long low table, 24" wide and the height of wheel. So 6 wheels on either side facing each other and one wheel on each end to make an island. If you're seated on either long side of the island there are storage racks behind you for studio members/students to store their clay and work in progress. When the studio is in use it gets pretty tight between the storage racks and the wheels/people throwing. So I'd like to rebuild the wheel pod/island tables to be narrower and potentially have two  fixed tiers or some sort of adjustable/track shelving to take advantage of height/levels and gain much needed walkway space.

    If anyone can share what their studio does for at-the-wheel storage it'd be greatly appreciated. I have a few ideas, but before I go and try to reinvent the wheel I figured I'd ask. Space is always a precious commodity in a clay studio, so I'm thinking there must be some folks on the forum who have been faced with this chellenge. 


  4. That fuse looks strange. Every glass tube fuse I've ever seen is clear glass with a wire running through the center. If the wire is intact, the fuse is good. If the wire has split, the fuse is blown. Usually when the fuse blows it also leaves the glass a little cloudy/dusty on the inside of the tube.... but not opaque. Is there a wrap on this fuse?

  5. To mimic the effect of two ramps per segment just set the hold for segment 1 as 0:00. Like others have said, there's no real benefit of having two ramps in a segment if you have 9 segments available. 

    Seg1: 100C/h to 600C; no hold
    Seg 2: 150C/h to 1200C; then hold for xx min/hours

    is the same as 

    Seg1: R1 100C/h to 600C; R2 150C/h to 1200C; then hold for xx min/hours

  6. Absolutely it would take a long time to dry. But wouldn't it take almost as long even is the vessel was only fired to bisque? Even with the vessel walls at 1" thick they it can only absorb so much water from the glaze before  the process relies on evaporation. I figure either way it'd be the type of thing where the glaze waste gets poured in then the vessel sits for a month or six weeks.

    Pouring into a puddle and loading the cylinder with dry glaze sounds like a good idea. Break out the respirator!

  7. hitchmss,

    Do you think it would be helpful to fire the glaze log containers to maturity with a liner to help prevent any potential leaking? I've been considering something similar to this for some time now but have been too concerned about a kiln disaster. I fire at ^6. I have been thinking I'd make a container and fire it to ^6 with a liner glaze to seal it, then fill it up with trash glaze and  after LOTS of drying fire to ^3 to get a decent melt.  Do you think this would help? Totally unnecessary? Either way I think firing the container in an additional sagger vessel as you suggestied would give me piece of mind. 

  8. I'd bring it to a machine shop and have new holes drilled at 10" center. If you can't get the old pins out... they look pretty well oxidized... the shop would be able to cut them off or grind them down flush. Then you can buy any of the standard 10" center bats that are widely available. If the wheel head is thick enough to have the holes threaded, have them tapped and threaded for 1/4 20, then you can screw your bat pins directly into the wheelhead without the need for a wingnut beneath. If the wheelhead doesn't have the thickness needed for threaded holes just have them drilled so that a 1/4 20 socket cap screw can slide through with just the tiniest touch of wiggle room.

  9. On 4/14/2018 at 1:12 PM, neilestrick said:

    I would never pay $700 for an old wheel. Just save up for a couple months and get a new one for $1000.

    On 4/14/2018 at 3:11 PM, S. Dean said:

    +1 for what Neil said.....  it amazes me what people want for used wheels, especially ones that are no longer supported by the manufacturer.  Someone recently wanted $400 for a 30 year old Creative Industries MP that wouldn't come to a complete stop  (even after the owner had adjusted the foot pedal and replaced the potentiometer).   This line of wheels became unsupported when Speedball purchased CI and the seller was all to well aware of this.   A new Shimpo VL Whisper or a Skutt Classic/Legend can be had for less than $1,150 delivered to your house, a Bailey for closer to $1,000, others even less.  Plus, you get a full warranty and no more wasted time chasing elusive leads.  This isn't to say good deals on used wheels can't be found, you just have to be in a position to be able to wait/jump on them when you see 'em. 


    +2 for what Neil said and +1 for SD. I don't think I've ever seen Bailey not offering free freight on wheels when shipped within the lower 48. For an extra few hundred just buy a new wheel. There are plenty of options in the $900-$1100 range. Or if you're willing to forego some of the bells and whistles, the Pacifica GT400s are a solid middle of the road wheel for $800. I run a community studio with 12 of these and they see constant abuse... I mean abuse... not the heavy workload of a production potter with understanding of/respect for the equipment... abuse like kids kicking the pedals off as if they were trying to break the floor beneath, people powering off the wheels while the pedals are still engaged, switching from FWD to REV without allowing them to come to a full stop, water everywhere, the list goes on. Occasional repairs (aside from the controller) are pretty inexpensive. The bearings/motors last 10-12 years in this type of environment. With basic care I'm sure this wheel would last many years beyond that.


  10. On 4/15/2018 at 3:06 PM, Rae Reich said:

    Yeahbut... every dud piece is a potential test tile too. Better to experiment on anything that will stand up (as long as you can afford the kiln space). Then when nicer pieces are ready, you'll have a little repertoire of successful glaze techniques to use on them. 

    Of Course you'll throw away anything that might embarrass you :)

    Yes, but every dud piece is made from and requires additional natural resources to complete. I am all for keeping some sacrificial lambs (particularly with beginning students I find it's important to keep a really high percentage of pieces both for learning all steps of the process and to keep students engaged), but keeping everything, especially when you are throwing with a level of proficiency shown in shawnhar's pictures seems a bit irresponsible to me... especially if there's an expectation of just throwing out pieces you aren't satisfied with.  

  11. I'm 45 minutes out from teaching my weekly mixed level wheel class so this was a perfect thread to find as I get into teacher mode. Lots of great feedback here already, but to add my two cents, the most impactful advice I give students is the simplest: focus on developing muscle memory of strong fundamentals.  Improving your wall evenness without having to rely on corrective trimming and developing more precision/intention/style in the trimming of your feet will progress your work much faster than learning how to new forms in a mediocre way.  There is a shift that I am always so happy to see in my students' work when the pots make the jump from looking like the clay was in control,  to communicating human command over the material. You're getting there, shawnhar! Focus on the basics, develop a true command over the material while making cylinders and bowls, then the fundamentals will carry over into other forms like planters, plates, vases, jars, etc. Repetitive throwing of basic cylinders and bowls, only to wire them in half to inspect then re-wedge them isn't the most glamorous or exciting exercise, but it sure is effective. 

  12. The policy of the community studio I manage is that we fire pieces how we find them. Most people fire with the lids on for the reasons already described by Min, but some others do fire lids separately. If lids clearly look like they'll fuse together with glaze we'll leave an "are you sure about this?" note before loading them. But in general we fire however each artist leaves their work. 

    When lids fuse I tell my students they've made top shelf jars... just display them at a height no one will be able to remove the lid and your secret will be safe. Unless you really do have some doors that need stopping. ;)

  13. On 2/19/2018 at 3:36 PM, Sputty said:

    Do report back if successful!

    Happy to report that microwaving the lithium crystals did work to get them back into solution. I used a blender to chop them up, covered them in some of the lithium-deficient slurry and nuked them for 2 minutes, stirring after 1 minute. I was a little nervous that they'd recrystallize due to the rapid temperature drop when I sieved the mixture back into the bucket, but they seem to be fine. Thanks for all the help y'all!

  14. Thanks so much, Min, for taking the time to run this exercise!

    Per an older thread about possible composition abnormalities in custer, reducing the overall percentage of custer seems like a good idea... if I get a funky batch of custer the impact on the glaze would be more mild (in theory at least). Also, the price reduction is a nice bonus. Just need to find a retailer of Fusion frits.

    I use iron laser decals in a lot of my work and have found that some of my ^6 glazes are not tolerant of the ^06ish decal firing.  Some glazes seem to begin fluxing in the decal firing, but without making all the way to ^6, so they are rendered soft, matte, scratchy, no longer food safe (using acid test). Will the chemical changes you've suggested alter either the stiffness of the glaze when fired to ^6 or lower the point where it begins to flux? Do you see any issue with this glaze begin brought back up to ^06ish? My iron decal program is 100/hr to 200 hold 0:30; 275/hr to 1810 hold 0:15.

  15. Thanks, Sputty, for sharing this! In my dismay at discovering the issue I didn't exercise the most patience, and jumped straight to posting a new thread, rather than searching through the resources already available. Per the linked thread, I believe it's the lithium carb that has crystallized due to inactivity and temperature drop.  I saved as many of the crystals as I could and will be microwaving them along with some of the now lithium-deficient glaze to get them back into solution.

    Neil, the recipe is as follows in case you have any other theories or can confirm that lithium is the culprit.
    Tin White Liner  ^6 Ox
    Silica: 2.1
    Custer: 64.4
    Zinc Ox: 5.4
    Gerstley: 14.5
    Whiting: 3.0
    Lithium Carb: 3.1
    Tin Ox: 7.5
    Bento: 2

  16. After letting a big batch of my tin white liner glaze sit for about six week, I’ve just sieved it to start working with it again and found a pile of glass-like crystals sitting on my sieve’s  screen. My glaze has been stored in a cold area (it our most recent cold snap the temperature inside my storage space probably got down to high 40s/low 50s) but it hasn’t been exposed to freezing temperatures.  Some of the crystals look like snowflakes, while others are just chunks.  Does anybody know what they are and why they developed in my glaze?  My hope is that they are just debris, but my better sense tells me that they’re one of the glaze ingredients. 

    Is it worth saving drying and weighing the crystals and then replacing an equivalent of the powdered ingredient into the wet glaze before using it?  Or can I just toss them and move on using the glaze as normal? 


  17. Like others have wisely mentioned already in the thread, function should dictate the form of the lid.


    The Val Cushing Handbook has a great section on lids. There are drawings of all sorts of different shapes, do's and don'ts, critical mistakes, tips, etc. When teaching lids to my students I'll share these pages and frame the discussion around function, then over the course of a couple weeks cover (no pun intended) 5 lids:

    - Basic Flange "The Hat" thrown upside down

    - Basic Gallery "The Bowl" thrown upside down

    - Flange + Gallery w/Inset Knob thrown rightside up

    - Flange + Gallery w/Attached Knob thrown upside down

    - The Russian Doll thrown as a closed form then trimmed gallery and flange

    So many lids, so little time.


    Someone also brought up firing lids atop their corresponding jar/teapot versus firing them separately. I'm all for firing lids along with their corresonding piece. Where the clay is going to experience change and movement as it shrinks, I want the set to experience all this change together as one piece.


    My two cents.



  18. I've had similar bloating issues with Laguna #65 and #90.


    It's interesting to hear that the presence of manganese can be a cause for bloating. At times I'll find a bag or two of the #90 that appears speckled with manganese, even though it's not supposed to be in there. It's almost as if the mixer or pugmill wasn't thoroughly cleaned after the batch before the #90 was mixed. If I see more bloating in this clay body I'll make note of whether it's (unexpectedly) speckled.


    At the studio where I work we often have tightly packed kilns full of thick-walled work made by youth. Surprisingly these were rarely the pieces which bloated. We'd see it in thinner, balanced, well-thrown pots... Maybe the kids' pots were so thick the bloats never made it to the surface. We'd been firing to ^07, and a bump to ^06 helped correct the issue. Our program is slow - I like to see 14:30ish - with a 4 hour hold at 200F and a 25 minute hold at peak (1800F).

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