May 20, 6:00pm. At the annual meeting we hold elections for board members. We
vote on any proposed amendments to the by-laws, and there is one amendment
proposed. Check your email for attachments. After all the agenda items are concluded we’ll
have a pot luck, so start thinking of
what you’ll bring to share.
Monday, May 13, 2013
May 12th Hint of the Week
Making Your Own Press Molds
from the Clay Times Pottery Forming Techniques
· Handbuilding of similar items is easily accomplished with the use of press molds of various shapes and sizes. But you needn't purchase them it's relatively easy and much more affordable to learn a few simple steps toward making your own mold.
·
By
far the easiest method is to make your large, rounded molds by throwing them on
the potter's wheel, then firing to bisque at cone 010 for molds that are sturdy,
yet porous and absorbent enough to release your hand-built forms as they dry.
The molds should be at least 1/2 in. thick, however, to absorb moisture
sufficiently. This technique may be used to make as many molds as you wish, in
any size you're physically able to throw or build and fit into your kiln. In
case of eventual breakage, it's a good idea to make at least two molds of each
shape/size so that you have a back-up handy for last-minute projects, in case of
breakage.
·
To
make a plaster mold, you'll need pottery plaster from your local supplier or a
bag of plaster of Paris (from the hardware store), water, a large bucket for
mixing, a jar of Vaseline, a flexible rib, and the form to mold, or
"model."
·
Start
by placing the model on a flat, clean surface, and setting a clay coil around
it, roughly 1/2 in. from the form. Next, apply a heavy coat of Vaseline to the
mold, the table surface, and the coil. Mix the powdered plaster with water as
instructed on the plaster bag and stir thoroughly, then apply to the model and
coil when creamy, at a thickness of at least 1/2 inch. Do not allow the plaster
to extend beyond the clay coil. As the plaster sets, scrape it smooth with a
flexible rib. Once it has hardened and dried (usually about 30 minutes or so),
it can be removed from the model and coil, and sanded on both sides. Let set for
about 24 to 48 hours to fully dry. The interior may now be used as a "slump"
mold; the exterior, as a "hump" mold. The ridge left by the clay coil offers a
useful ledge for lifting the mold.
a.
To
use the mold, drape with a soft clay slab, then remove the slab when leather
hard; trim, decorate, and fire as usual. Be careful, however, not to let any
plaster chips remain in the clay, as they will cause large pop-outs during
firing. When cleaning up, let plaster dry and put in the garbage don't
rinse down the drain, or it will clog the pipes.
May 5th Hint of the Week
A
few words about Wood Throwing Bats (from Northstar) with Some
minor edits for clarity by Big Ceramic Store and CAG
We (Northstar)
are not able to control the way bats are used nor the environment in which they
are used…
If drilled for
standard bat pins, every…bat…is physically checked on a wheelhead… Even such
checking does not always guarantee a perfect fit, however, for several
reasons:
- Bat pins are off-the-shelf hardware items. Most American wheels use a 1/4-20 socket cap screw, which you can buy at any hardware store. The head is approximately 3/8” in diameter and industry standards allow quite a bit of variation in the diameter of the head of this screw.
- Not all wheel manufacturers allow zero tolerance between bat pin holes. There may be several thousandths of an inch (and sometimes much more) variation from wheel to wheel from the same maker
- Most wheel manufacturers drill an unthreaded hole in the wheelhead to receive the bat pins, and there is always some (and sometimes a lot of) extra clearance.
If the fit is
less than perfect on your wheel try these steps in
order:
- First, try loosening the wing nuts of the bat pins and moving them for a better fit.
- Next, touch the holes of the bats slightly with a small rat-tail file (available at any hardware store). You may have to file on one side or the other of the holes.
- Finally, if the holes appear to be located correctly but too small, either use a rat-tail file or try another set of bat pins, which could be a few thousandths smaller.
- [If holes eventually seem to get too large, try putting clay on them and then put the bat on].
Care of your bats
The life of all
wood-derived bats (such as Masonite and Medex) can be extended by taking
reasonable care of them. Always
- Clean them after each use.
- Avoid [over “soaking” them] or keeping them wet for long periods of time.
- Avoid flexing or bending them when they are wet.
- [Bats should be stored and dried vertically not horizontally].
Warped bats can
usually be flattened by drying them [horizontally] with weight on
them.
Reversing
them each time you use them (flipping them over) is the single most important
thing you can do to extend the life of your bats.
April 28th Hint of the Week
Miscellaneous Decorating Tips. Copyright 2000, Cindi Anderson, www.bigceramicstore.com
1. Save old phone books for
practicing brush strokes.
2. Put coffee grounds or sawdust in
your decorating slip. The coffee grounds burn out leaving a brown color behind.
The sawdust leaves a fine texture which can be stained for enhancement.
3. To enhance textured surfaces,
brush glaze on so it gets in all the cracks, and then wipe off the top surface.
4. Cotton lace, burlap, cheesecloth
or other cotton, absorbent materials can be soaked in slip and added to pieces
for interesting textures. Soak fabric in slip, squeeze out lightly, brush on
leather hard clay surface, dry slowly, and bisque. The fabric will burn out
leaving the slip texture behind.
5. To remove oxide from bisque
(mistakes or for designs) use a rubber pencil eraser. It won't smear like trying
to wash the oxide off.
6. When applying oxide over dry
glaze, the glaze sucks the water out of your brush making it difficult to paint
clean lines. Lightly mist the glaze first with water, and the oxide will flow
smoothly.
7. A few drops of glycerin (from the
drugstore) added to engobes, stains, oxides and slips slows drying time and
increases workability.
8. To remove unwanted wax from a
piece, rebisque it or microwave it on high for 5 minutes.
9. When glazing a thin piece, glaze
the inside then wait for it to dry thoroughly before glazing the outside.
Otherwise the clay may be saturated and glaze won't absorb and stick to the
outside. Some people wait overnight.
10.
Glaze pinholes often form in areas that have been trimmed, as trimming tends to
open holes in the surface. To prevent, slightly burnish the trimmed area, or rub
the slip from throwing over the area to fill the
holes.
Wednesday, April 24, 2013
April 21st Hint of the Week
Oldest pottery hints at cooking's ice-age origins In New Scientist June 28, 2012 by Michael Marshall
Did a deep freeze spur our ancestors to get cooking? The discovery that the oldest pots in the world were made in China around the time of the Last Glacial Maximum suggests that might be the case.
Hundreds of fragments of pottery have been found since the 1960s in Xianrendong cave in south-east China
Ofer Bar-Yosef of Harvard University and colleagues excavated the cave again in 2009 and, for the first time, used radiocarbon dating to work out the age of the layers where the pottery shards were found. The oldest ones turned out to be between 19,000 and 20,000 years old.
That is thousands of years before people began farming some 12,000 years ago – suggesting that the pots were made by hunter-gatherers, which is contrary to previous thinking. "The making of pottery is not necessarily related to agriculture," says Bar-Yosef.
Is this a piece of 20,000-year-old cookware? (Image: courtesy of Science/AAAS)
World's first stew
Bar-Yosef thinks the shards are the remains of crude pots and bowls, probably about 20 centimetres across. "They were poorly fired and easily breakable," he says. Their outer surfaces carry scorch marks and small amounts of soot, so Bar-Yosef thinks they were used for cooking.
His dating data helps to locate the oldest potters, but humans had been manipulating clay into figurines for many years by then. The Venus of Dolní Věstonice, a small statuette of a naked woman found in what is now the Czech Republic is estimated to be about 30,000 years old.
What prompted Chinese hunter-gatherers to start cooking food 20,000 years ago? Bar-Yosef points out that, at the time, Earth was in the clutches of the Last Glacial Maximum, the height of the last ice age.
The extreme cold would have caused food shortages. Cooked food yields more energy than raw food, so throwing their meals on the fire could have helped people to survive. It takes some form of stress for species to undergo major changes, says Bar-Yosef.A later cold period, the Younger Dryas starting about 12,800 years ago, could have forced people to start farming (Current Anthropology, DOI: 10.1086/659784). Because much of Eurasia was colonised by then, people couldn't escape food shortages by moving to a new area. The only option was to start growing crops.
Did a deep freeze spur our ancestors to get cooking? The discovery that the oldest pots in the world were made in China around the time of the Last Glacial Maximum suggests that might be the case.
Hundreds of fragments of pottery have been found since the 1960s in Xianrendong cave in south-east China
Ofer Bar-Yosef of Harvard University and colleagues excavated the cave again in 2009 and, for the first time, used radiocarbon dating to work out the age of the layers where the pottery shards were found. The oldest ones turned out to be between 19,000 and 20,000 years old.
That is thousands of years before people began farming some 12,000 years ago – suggesting that the pots were made by hunter-gatherers, which is contrary to previous thinking. "The making of pottery is not necessarily related to agriculture," says Bar-Yosef.
Is this a piece of 20,000-year-old cookware? (Image: courtesy of Science/AAAS)
World's first stew
Bar-Yosef thinks the shards are the remains of crude pots and bowls, probably about 20 centimetres across. "They were poorly fired and easily breakable," he says. Their outer surfaces carry scorch marks and small amounts of soot, so Bar-Yosef thinks they were used for cooking.
His dating data helps to locate the oldest potters, but humans had been manipulating clay into figurines for many years by then. The Venus of Dolní Věstonice, a small statuette of a naked woman found in what is now the Czech Republic is estimated to be about 30,000 years old.
What prompted Chinese hunter-gatherers to start cooking food 20,000 years ago? Bar-Yosef points out that, at the time, Earth was in the clutches of the Last Glacial Maximum, the height of the last ice age.
The extreme cold would have caused food shortages. Cooked food yields more energy than raw food, so throwing their meals on the fire could have helped people to survive. It takes some form of stress for species to undergo major changes, says Bar-Yosef.A later cold period, the Younger Dryas starting about 12,800 years ago, could have forced people to start farming (Current Anthropology, DOI: 10.1086/659784). Because much of Eurasia was colonised by then, people couldn't escape food shortages by moving to a new area. The only option was to start growing crops.
April 14th Hint of the Week
Miscellaneous Handbuilding Tips
copyright 2000, Cindi Anderson, Big Ceramic Store
1. Having trouble with clay sticking to your molds, rolling pins, and canvas?
a) Use pantyhose to cover molds, rolling pins, etc.
b) Sprinkle the surfaces with cornstarch. It will burn off in the kiln.
c) Cover items with Saran Wrap or newspaper.
d) If you're using the slab roller a lot, the canvas can get wet and cause sticking. Use separate pieces of cloth (old sheets are great and you can get them at garage sales for 25 cents) or thick plastic instead of placing the clay right on the canvas.
2. To keep tiles and other pieces of clay flat as they dry, sandwich them between pieces of drywall. You can stack many layers this way.
3. To support your slabs while handbuilding, try cutting your templates out of roofing paper (tar paper) or cardboard. They will support the slabs so you can assemble them while they are still soft. Keep it attached until the clay hardens, then peel off.
4. Make slabs in advance and keep them wet for ages in Styrofoam coolers. If they start to dry out, throw a wet towel over them.
5. When carving into leather hard clay, first cover the surface with Saran Wrap. You can draw your pattern on it with a marker. And when you carve there will be no burrs.
6. When cutting clay pieces, first dip your knife in vegetable oil so it glides right through the clay. WD40 works also, but has a chemical smell. Both will burn off in the kiln.
7. For random textured slabs, impress food objects such as coffee grounds, wheat bran, and rice. Just make sure you don't get pieces of rice entrapped in clay or they may cause an explosion when firing. .
8. Finally, repeating from an earlier tip, use vinegar to attach clay, it works like magic. And if you are trying to attach pieces to work that has gone past leather hard, wrap it all in wet newspaper, then plastic. The moisture will even out and the pieces will stick.
copyright 2000, Cindi Anderson, Big Ceramic Store
1. Having trouble with clay sticking to your molds, rolling pins, and canvas?
a) Use pantyhose to cover molds, rolling pins, etc.
b) Sprinkle the surfaces with cornstarch. It will burn off in the kiln.
c) Cover items with Saran Wrap or newspaper.
d) If you're using the slab roller a lot, the canvas can get wet and cause sticking. Use separate pieces of cloth (old sheets are great and you can get them at garage sales for 25 cents) or thick plastic instead of placing the clay right on the canvas.
2. To keep tiles and other pieces of clay flat as they dry, sandwich them between pieces of drywall. You can stack many layers this way.
3. To support your slabs while handbuilding, try cutting your templates out of roofing paper (tar paper) or cardboard. They will support the slabs so you can assemble them while they are still soft. Keep it attached until the clay hardens, then peel off.
4. Make slabs in advance and keep them wet for ages in Styrofoam coolers. If they start to dry out, throw a wet towel over them.
5. When carving into leather hard clay, first cover the surface with Saran Wrap. You can draw your pattern on it with a marker. And when you carve there will be no burrs.
6. When cutting clay pieces, first dip your knife in vegetable oil so it glides right through the clay. WD40 works also, but has a chemical smell. Both will burn off in the kiln.
7. For random textured slabs, impress food objects such as coffee grounds, wheat bran, and rice. Just make sure you don't get pieces of rice entrapped in clay or they may cause an explosion when firing. .
8. Finally, repeating from an earlier tip, use vinegar to attach clay, it works like magic. And if you are trying to attach pieces to work that has gone past leather hard, wrap it all in wet newspaper, then plastic. The moisture will even out and the pieces will stick.
Tuesday, April 9, 2013
April 7th Hint of the Week
Hand Position for Raising the Clay
You Tube and the internet are great places to learn about clay and how to form it. Here is one You Tube video that may help you do a better job raising (pulling) the clay when you throw:
You Tube and the internet are great places to learn about clay and how to form it. Here is one You Tube video that may help you do a better job raising (pulling) the clay when you throw:
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