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Lesson Plans

Re: Have Advice for Ceramics??

[ Thread ][ Subject ][ Author ][ Date ]
L Skeen (
Tue, 28 Dec 1999 19:09:02 -0500

Larry Seiler wrote:

> For one...I have a bunch of round masonite boards with peg hole spots to
> fit on Brent wheels. I didn't see any pegs for them to fit onto the
> wheels. The wheels have some old clay in the peg holes, so...I'm
> wondering, are the pegs hidden? Should I just use some clay slip and
> attempt to attach the boards to the wheels that way? I know we used to do
> it that way with plaster bats.

The round masonite boards w/ holes are called bats. The holes are for bat
pins, which are apparently missing on your wheels. To attach the bat to the
wheel head, you will have to make a "snake" of clay and attach it to the wheel
head, then let the wheel turn a bit while you make your snake flat and evenly
distributed around the wheel head. Place your bat on top of this clay and pop
it in the middle w/ your fist to seat it firmly. If you're not up for all
that, you'll have to teach the kids to throw w/out bats, which is not a bad
idea anyway. They can wire under, then lift pots off w/ first 2 fingers of
each hand in a V shape around the base of the pot. Takes some practice, but
it's how production potters get the job done!

> I discovered we have one portable plaster filled table, about 20" by 40" to
> wedge clay on, but the plaster is all cracked, and chips come out in the
> clay.

This is bad news, Larry. The plaster will cause blow-outs in your kiln, which
will ruin the pieces, and possibly damage others' work as well as the kiln.

> I've never done this before, but should I break up all the plaster, empty
> the frame out and attempt to mix up and fill it with new plaster? IF so, I'd
> appreciate some advice on that! Is this a special kind of plaster?

You don't have to break up ALL the plaster, but I'd dig out about 2" all over,
as level as you can make it. Saturate, and I mean really soak it down, the old
plaster just before you mix the new, then pour the new plaster over the old.
Let it cure out about a week or so before you use it. You soak down the old
plaster so it won't suck all the water out of the new plaster and render it
nasty. :) You can buy the new plaster in bags from Home Despot or any pottery
supply catalog.

> I haven't found any cutting wire for air bubbles either, so will probably
> have to build one.

Not a problem; just be sure you get wire that won't stretch, and attach it
well. Folks trying to cut too-hard clay will ruin the wire if it stretches or
if the attachments come loose.

> I've got three barrels of hard dried clay, (reclaim), and about a dozen boxes
> of new/wet clay. Its a red clay...and seems to soak up water well and soften
> quickly. Enough so that we threw some pots. Not used to this type of clay,

Do you know ANYTHING about the clay: where it came from, what cone it fires
to, etc? If you know the name or where it came from I may be able to help you
find firing temp if you don't know. What are you doing for glazes?

>>Got to familiarize myself with operating this electric kiln.

Operating the electric kiln is very easy. Assuming you're firing a kiln w/out
electronic computer, and with a kiln sitter, turn all switches to OFF and do
the following:

1. Place cone horizontally in the sitter, with the flat part of the cone on
the 2 bottom "arms" and the center bar of the sitter on the point of the cone.
On the outside of the kiln, raise the switch/latch into position. There will
be a button in the center of the latch. Press this IN.

2. Load your BONE DRY ware. Anything wet in the bisque kiln is an invitation
for explosion.

3. Close the lid and put in your peeps.***

4. Turn all switches to LOW. If you have dial switches with numbers like 1 -
10 or so, turn them to 3.

5. Turn on your envirovent or whatever ventilation system you use. Go away
for 2 hours.

6. Turn all switches to MEDIUM or about 6 if your dials have numbers. Go away
for 2 hours.

7. Turn all switches to HIGH or the last number on your dials. The
temperature in the kiln will continue to climb until it reaches the temp that
melts your cone, at which time, the cone will "break", releasing the
switch/latch, and the kiln will shut off.

8. Let that sucker cool down to the point you can stand to touch the outside
w/ your bare hand before you open it. Crack the lid and prop it open w/ a kiln
post until all warm air stops pouring out the top, and you're ready to unload.

*** Some people leave their peeps out until they turn up to High in order to
let the nasties outgas. If you don't have a good ventilation system, plug the
peeps from jump street.

Another caveat: When you're waiting for a glaze firing to cool down, you
really don't want to open the kiln too early for a couple of reasons. 1. Some
glazes develop their color during the cooling process. I have a fabulous red
glaze that is BROWN while still hot. 2. If you open the kiln and hear a lot
of pinging, it could be because of cold air hitting hot pots and the glaze is

If you open a cold kiln and hear a lot of pinging, it's probably due to a glaze
fit problem between your glaze and clay - ie: the glaze shrunk more than the
clay did, or vice/versa. This can cause shivering, which is where the glaze
pops off the pot in razor sharp slivers, so watch out for that! :)

Good luck!

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