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perkolator

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Posts posted by perkolator

  1. A lot of people come and ask me about used kilns they either see for sale or have been offered.  Besides looking for the obvious things mentioned above, one of the most overlooked things I've noticed is that people don't pay attention to the power requirements and somehow end up looking at 3-phase kilns instead of 1-phase that most residential has.

     

    Yes, pretty much any kiln with a sitter can be converted to a digital control box.

  2. I have no science behind this, but if you're crash cooling at the top end of your temp you're going to end up pulling in significantly cooler air through your peep holes - could possibly thermally shock hot elements and brick local to the peeps.  I do it because I already know I'll be working on my kilns continuously through the year, some home ceramicists might not ever touch their equipment until it breaks.

     

    Sometimes you just gotta do what you gotta do.  I've been known to crash cool the student's work in a big gas kiln firing - just leave the damper and burner ports fully open and remove the spys.  Below maybe 500* I'll crack the door open and put on the blowers.  Usually this is only when we are on a time restriction, usually for critique.

  3. For a damp box it likely won't make any difference since I'm assuming it's the type with just a slab of plaster.  If it's slip casting molds then it likely would.

     

    I've always known regular gypsum plaster to be "weaker" than the Pottery #1.  Your mold will degrade faster and won't hold the detail as long.  I also think they have different absorption rates.

  4. You can use either Frit, Gerstley Borate, or make an underglaze with equal parts clay color and flux.  Frits, being fired material usually leave a gritty/sandy texture to the wash, some people use CMC, laundry starch, karo syrup, etc to help.  Usually I use GB and CMC gum solution, sometimes add a little bit of EPK in it too.

     

    Look up Linda Arbuckle's majolica notes, she's got a lot of suggestions for combos of washes.  Most are by volume, not weight.

     

    Here ya go: 

    http://lindaarbuckle.com/handouts/majolica-handout.pdf

    http://ceramicsweb.org/articles/arbucklemajolica.html

  5. since we essentially duplicate the process of forming rocks, all of our ceramics is permanent and will be here until it melts again with some great force of energy.  maybe some sort of ultra hot explosion from warfare, volcano or lava flow, or perhaps heat from asteroid colliding with Earth.  with that said, there is a lot of terrible ceramics out there that will be here forever.

  6. our students do this all the time with both commercial tile and dinnerware from thrift stores.  simply use low-fire commercial glazes and underglazes.  decals also work.

    definitely make sure you test fire the object at the temp you plan on firing to BEFORE you do your entire kiln full of them - sometimes we'll come across a random tile or plate that looks all good, only to find a puddle where it sat in the kiln.  also, not all colors work with this technique - for example greens with chrome sometimes don't fuse well or flux out with the existing glaze

  7. technically speaking clay can be VERY thick, you just have to fire it very slowly - think of a brick, those are 2.5" thick and they don't explode in the kiln.  also, it's not just the preheat that needs attention to drive off physical water, you also need to fire very slow since the chemical water in your clay needs to escape the core of the work.  lastly, there is down-firing involved with thick ceramics or your pieces will crack when cooling.  i've got a decent amount of experience firing thick work - usually firings take 3-5days when you get into the 2" thick range for life-size sculpture.

     

    for this particular piece since you added the features to another form, my guess is that there is less chance of "explosion" (unless you trapped air when applying the face) than there is for the added features to heavily crack (or crack and fall off).  you'll be fine, just fire slow.

  8. first thing i would do is figure out how to get those drains snaked because i'd bet that's half your problem.  i'd even guess your custodial staff has one in their supplies as i've always know them to have at least one to test out before calling up a plumber and pay money.  if not, you could rent one or better yet buy a cheap $10 25ft hand-crank snake from Harbor Freight (maybe even use a 20% off coupon since you can usually find a dozen in one Sunday paper) to keep in your classroom since this may be needed in the future.

     

    if your sink doesn't have one yet, look into either buying or fabricating a sink drain trap to catch any materials that make it past an in-sink pre-trap.  If you do some Google searching you can find many simple plans for making a sink trap out of buckets or rubbermaid tubs, etc and most likely under $20 in parts that will save a lot of future headache, or just buy one.  for in-sink contraptions, many people have different setups for this type of trap.  some variations i've seen are the "overflow tube" setup (like being described above with a tube that raises the drain and only lets cleaner water past it), busser tubs in the sink, multi-bucket setups, single bucket setups, etc etc.  

     

    one of the simplest ones I've seen is simply a 5-gal bucket with many small holes (1/8"?) drilled around the top lip about 1" down from the top edge.  This 5-gal bucket sits inside of a busser tub, that was sitting inside the sink.  5-gal bucket is mainly for pre-rinsing hands and tools, when water level gets to the holes it spills over and flows into the 2nd tier/busser tub.  The 5-gal bucket is deep enough to settle most of the clay and the 1/8" holes act as a filter; the 2nd tier is a secondary settling trap that helps keep clean water only going down the drain.  

     

    even just having a separate bucket or trash can full of water for doing a pre-wash on hands and tools could be the solution to your problem.  ultimately though, teaching your students good studio habits will help the most.  having a backed up sink is a good time for them to learn since they can physically see the repercussions of putting clay down the drain.  

     

    Good luck!

  9. pretty much any white slip recipe can be made into a colored slip. for most natural oxides you will use the same percentages you would in glaze recipe (so like 2% for cobalt carb = blue) if using a mason stain, you'll want to be up near 10%. my go-to basic white slip recipe is equal parts (25/25/25/25) of EPK, OM#4, Silica, and Custer Feld. you can easily tweak this recipe with flocculants/deflocculants or suspension agents to get the consistency you desire. this slip can be used at pretty much any temp range.

     

    for a raised slip/heavy surface texture, i prefer "Arnie's Fish Sauce" and i believe it's a midrange/stoneware recipe. Mix it THICK, like yogurt or even cream cheese. this can also be colored.

    43.6 Grolleg

    15.6 Silica

    23.4 F-4/Minspar/soda spar

    7.8 Pyrax/Pyrophyllite

    9.5 Bentonite

  10. one of our faculty has a large AIM oval kiln that is over 15yrs old. she fires it all the time and never had any problems with it until a couple years ago when she burned through a couple sections of elements with glaze drips. to my knowledge, it's only had the elements replaced the one time (all of them), 2 relays, and one kiln sitter tube assembly - I would say that's a pretty good kiln. one thing I really like about the AIM is that it has clamping connectors for the elements instead of crimped like on a Skutt - I'm guessing it's slightly less efficient in terms of resistance, but sure is a WHOLE lot easier to work on. I will admit though - trying to get those elements for this kiln was a chore and took several weeks - so I guess AIM still has a little bit of residual issues on their end. If I were to recommend a new kiln to someone it most likely won't be an AIM, but instead one of the currently better-known makes like a Skutt or L&L, etc.

     

    most 120v kilns I see are all kiln-sitter type and they should all fire the same with this type of controller. chamber size:elements ratio is pretty much equivalent between all of them so you really shouldn't see much difference. also x2 on watching the voltage requirements - I have an old Cress 120v kiln that I wasn't able to use for a long time because it takes a 30A plug that I didn't have.

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