Beowulf wrote:

On Sun, 14 Dec 2003 02:52:36 +0000, Suzan wrote:
..

Beowulf, please get a few books on pottery from your local library.
You need
an overall grounding before you proceed any further, in order to avoid
wasting your time as well as harming your health. Unless, of course,
you're
just trolling. There are many basic pottery books which will answer your
questions...



Susan, several books on pottery, ceramics, and glazing are on the way
from amazon, ordered them last week, they should arrive any day now. I
just like asking questions, pondering the possibilities. Not trolling,
honest. I have a wheel and have made several pieces, and called
yesterday to the local ceramics supplier that does up to ^8 firing--
they said they will let me fire a whole batch (20+ pieces) for
about $20
dollars-- things are looking good!


Beowulf,

Tried to send this message directly to you instead of the newsgroup. I
guess you are intentionally being anonymous.


Folks aren't trying to be mean or discouraging when they suggest you
read some books or take a class, they are honestly giving you the best
advice they have. Some of your questions are so "newbie" they are a bit
terrifying.

Most of us took classes or worked directly with a knowledgeable potter
for years before we launched on our own. Personally this approach was
invaluable to me. Throwing pottery is something that honestly takes
years to learn and master.

Your enthusiasm is wonderful but I am afraid that it might be getting
you in over your head. There is no chance that you will think to ask
all the questions you need to know. We don't want you to kill yourself.


Specifics about the bisque cycle.

1- The bisque cycle is done in a kiln.

2- The bisque cycle takes about 17 hours (with large variance) to complete.

3- The pieces should to be bone dry before placing in the kiln.

4- The pieces can actually touch when they are being bisqued.

5- Some folks do not use shelves and stilts when putting pots in the
bisque. This is a more advanced technique and I do not recommend it for
at least the first 20 bisque firings you do. (unless you have an expert
to help)

6- The purpose of the bisque firing is to burn off impurities, and make
the piece easier to handle in the glazing stage. (You need to know what
type of glazes you will apply to make this choice. Glazes are
formulated differently for pots including a bisque cycle and those are
single-fired.)

7- At this point in time, using a bisque cycle is the standard in the
US and single-firing is a generally only done by advanced potters or
traditionalists.

8- Each potter controls the bisque cycle differently.

9- Some clay bodies specify the bisque "cone" they recommend. If this
is your case use the recommended cone.

10- Otherwise, I recommend bisqueing to 06-04 range if you are doing a
glaze fire to Cone 6 - 10. Personally I bisque to 04. I find I have
fewer problems with the glaze if I do this higher "heat work". This is
especially true for large pots. Your glaze fire temperature must match
the maturation cone. Commercially available clay states a glaze firing
cone range. Glaze firing higher than recommended will ruin your pots -
they will melt. Glaze firing lower than recommended and they will not
be vitrified and therefore will not hold water/food. (Note I am
assuming you are not using low fire clay.)

11- The kiln (and the room the kiln is in) must be vented appropriately.
Potters have died from inadequate ventilation. This is not an
exaggeration or a long term cumulative effect.

12- In the bisque cycle I recommend raising the temperature slowly until
the kiln is at ~ 212F. I do this with my spy holes open at least for
part of the time.

13- I also recommend raising the temperature slowing when you get to
within 200F degrees of the endpoint.

14- I usually soak at my top bisque firing temperature for 10 minutes

15- I generally let the kiln cool naturally after holding the bisque
temp. On a glaze fire and sometimes with porcelain bisque I ramp the
kiln down.

16- I usually wait until the kiln has cooled to 200F before pulling the
spy hole plugs and cracking the lid. Probably overly cautious.

17- The color of bisqued pieces range from gray to white to pink to
light brown. Don't worry the clay color will change again during the
glaze fire to match the promised color. This is especially true if you
are using a gas kiln.


Other notes/thoughts:
- Bisque pieces are not the final size of your pieces. They will shrink
more in the glaze firing.

- Bisque pieces will need to be dusted off before applying glaze.

- If you are responsible for making your own glazes you need to be
careful and accurate. Careful since some of the glaze materials are
hazardous to your health. I use a respirator mask with replaceable
cartridges that is approved for use with silica - a dusk mask does not
adequately protect you. Accurate in that I recommend a triple-beam
balance or equally sensitive electronic scale. A kitchen scale is not
accurate enough to properly make glazes. If you will be firing to Cone
6 then I recommend "Mastering Cone 6 Glazes" by John Hesselberth & Ron
Roy. I think this is an excellent book. Frankly, since you are doing
this by yourself, I recommend buying premixed commercial glazes until
you are more comfortable with the other aspects of creating pottery.
They are more expensive and in the long term probably not what you will
want. They will get you started and running. (The people in charge of
the kiln won't be thrilled if you misformulate a glaze and it ruins
their shelves and/or someone elses work. There should be no glaze on
the bottom of the pot. Depending on how runny your glaze is then I also
recommend a band of bare clay on the bottom of the sides. (I generally
leave 1/4".)

- When you talk about glazes you also need to know if the kiln is an
oxidizing or a reducing environment. There are different glazes for the
two environments. If it is an electric kiln you have access to then it
will be an oxidation environment. (There are weird things you can do to
make it reduction but ignore these more advanced techniques for now.)


Hopefully, someone else will bisque and glaze fire your pieces at least
the first few times.

Good Luck,

Kobey