Bosworth on thu 9 may 02
So may questions...not enough experience...need help!=20
I have fired this kiln around 8 times (this is my first gas kiln, had =
never fired one before this- learned a lot with a lot to go...), It is a =
downdraft forced air propane burner kiln (two burners in back). Hard =
brick inside, soft outside. I fire slow and let it slow cool. I fire =
porcelain with just salt and stoneware with salt, soda ash, baking soda, =
sawdust, and borax (maybe too much stuff to be introducing?- though it =
would give more texture and flashing).=20
Porcelain Firing Questions
1. How do you keep the lids from sticking when fired in place? I wax =
them with wax that I have added aluminum hydrate to, but they still =
stick. I have no glaze on the outside. I did take the kiln to cone 10 =
flat. Is there any other resist to put between the lid and pot? =20
2. What are the black crystal like substance on the floor of the kiln =
coming from the bag area? Is it harmful?=20
3. Why did a few of the pots on the floor of the kiln look like they got =
burned in spots at the bottom of the pots and slightly up the sides? It =
is like a flash but burnt looking?
4. why did some of my handles and a few spots on pots turn bright white =
while the rest of the pot is gray from reduction? The handles are =
literally white in the middle section and gray next to the pot. What's =
up with that? one pot just has a white streak in the middle of the pot =
about 1" long and 1/2" wide. Weird...
Stoneware Firing Questions
1. Why did the same blue glaze I used on the porcelain that looks =
fabulous look crazy on stoneware. It looks like it missed spots, ran off =
spots on the pot (clay shows through), small spots all over in almost a =
patterned sequence. Not good! Both blues I used did this, but did not do =
this on porcelain. I am using highwater aurora & hestia.
2. Why do I only get the beautiful flashing and orange color and soda =
buildup that I want on the bottom of pots, not on the sides or insides? =
I'm contemplating firing things upside down. What is the secret to this =
look? why did I get this on only one bowl? I did not use a slip on this =
bowl, it was just raw clay. I want to find a clay that I do not have to =
use a slip to achieve this look. I know this is possible because I get =
it on a few pots each firing, I just need to figure out how to have this =
happen more regularly. The rest of the pots in the kiln that are natural =
outside are UGLY! creamy with gray specs.=20
3. How do I get plates not to warp? I had heard about putting aluminum =
hydrate powder on the shelf and sticking the plate on this, won't this =
fly around the kiln and land on other pots? Is there another solution? I =
put one of my plates in a friends reduction gas kiln and it did not warp =
so I'm almost certain it is the wads and not technique.
4. same as above... lids sticking? banging my head against the wall!!!
5. why do I get great salt buildup on porcelain and not on the =
stoneware?
I know I am new at this and experience will probably solve some of these =
problems, but a nudge in the right direction would be great! I have read =
and read, and maybe I am not reading the right books, but I am =
thoroughly confused, mystified, and happy this is my job! Any help would =
be greatly appreciated.=20
Heather Bosworth
St. Helena Island, SC
visitors welcome!=20
Mercy Langford on thu 9 may 02
hi Heather- I'm also a rookie and can't wait to hear what the group advices
on the warping and lid issues. I was able just yesterday to save a lidded
box that had fused together. I had read in a little booklet for potter that
if you play a few minutes with cold water and then very hot water you are
able to separate them. It has to do wwith expansion and contaraction.
Anyways this is what I did and by golly it worked.! I got to kitchen bowls
fileed one with cold water and stuck some ice in it and the other bowl with
water stuck it in the microwave for 2 minutes. Then I put the box in cold
for a minute and quickly into the hot. Did it twice and tthen pressed a
kitchen knife slightly inbetween and it worked! It doesn't solve the
problem
itself but it might help you save some of your things. Mercy
Craig Martell on thu 9 may 02
Heather wanted to Know:
1. How do you keep the lids from sticking when fired in place?
Hi:
Wad the lids. Use a mix of kaolin and alumina hydrate oralumina
oxide. Make little wads a wee bit smaller than a pea and glue them with
Elmers glue and then set the lids on.
2. Why do I only get the beautiful flashing and orange color and soda
buildup that I want on the bottom of pots, not on the sides or insides?
Orange flashing usually occurs where the salt glaze is lighter, or on high
alumina slips. The bottoms of your pots are getting less salt.
3. How do I get plates not to warp?
Wash some of your flatter shelves and set the plates on these. Apply the
wash very smooth and even. You could use more wads too and make the foot
beefier.
5. why do I get great salt buildup on porcelain and not on the stoneware?
Your porcelain may have a higher silica/alumina ratio. In bodies where the
silica/alumina ratio is 5.0 or higher one can expect to get a better
salting. If your stoneware body has iron bearing clays or added iron, this
will resist salt glaze too.
regards, Craig Martell in Oregon
Cantello Studios on fri 10 may 02
Otto once told me to make flat pancakes and kiln wash them.
I think this may work on your plates. I have seen him use wades
As well but more in the wood kiln.
I hope this helps. Chris Cantello
| |
|
