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cone 5 vs cone 10 claybodies

updated sat 19 oct 02

 

Cat Yassin on mon 14 oct 02


Hola! I have a question about using a Cone 10 claybody vs. a Cone 5 when
firing Cone 6 glazes. Sorry if its an often-asked question, I can=92t seem t=
o
access all the old Clayart discussions. For some reason about half the
topics I try to access give me a =93Page cannot be displayed: There are too
many ppl accessing the web at this time=94 (but that=92s a whole nuther prob=
lem
isn=92t it?). Anyway, I love using B-mix. I use it to throw and handbuild
with minimal problems. I use Cone 10 glazes AND more recently Cone 6.
Because of this I like to stick with the same claybody so I don=92t end up
with meltdowns at a higher firing range. This also gives me flexibility in
deciding what type of glaze I want to use after I have made a piece. Am I
asking for too much freedom in the production process this way? My concern
is that when I use a Cone 6 glaze on a Cone 10 B-mix that the clay will be
insufficiently vitrified for my functional work (mugs, bowls, plates). I
have used the Cone 5 B-mix for my Cone 6 glazes and had no problems. Maybe
I=92m going to have to tinkle or get off the pot with this decision and use
the different range clays for each glaze process, but I don=92t want to if I=

don=92t have to.

Thanks in advance!

-Cat Yassin
S. Texas

June Perry on mon 14 oct 02


We used to use BMix as a Raku body. Unless they have altered it recently,
it's is a very open body and isn't vitrified at C10 which could present a
problem down the line. If the absorption of a claybody is too high and you
have a glaze with some crazing, someone using a mug like this to heat coffee
or tea in the microwave may some day experience an explosion from the built
up moisture in that non vitrified body. If you're lucky, it won't happen when
they're holding it; but why even take the chance!
As far as the Cone 6 glazes on the BMix, it might be OK if you're making
things like lanterns, soap dispensers, boxes, little sculptures, etc. or
anything else that is not meant to hold food or liquid. Of course, the body
may be pretty weak fired at least 4 cones below the recommended range.
It's easy enough to use two different clays in the studio. You might want to
consider using a cone 6 iron bearing stoneware, so you easily distinguish
between the two bodies. Or switch to a C10 iron bearing stoneware which has a
better absorption rate.
Another thing is to just mark the bottom of your pots with the cone number,
as you make them.
I've bdoing a lot of testing recently and am working with C10 and C6 bodies
at the moment and I'm doing just that and I have separate scrap buckets for
each of the claybodies. So far, so good.

Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/index.html

Lily Krakowski on mon 14 oct 02


This is a bit confusing.

You want to stay with your c.10 clay body. You want to use c.6 glazes on
it. And fire to c.6. You plan to make functional ware.

Is that right so far?

If so. (And I do not know what B-Mix is, I assume it is the name of a clay
body.

In my Bailey catalog there is a c.10 stoneware body listed as having 4.5%
absorption at c. 4 and .85% at c. 10. Another is listed as having 6%
absorption at c.4 and 3% at c.10 A mid- range body is listed as having 4.5%
absorption at c.4 and 2.5% at c. 6. Another is listed as having 2.5%
absoprtion at c.4 and 1% at c.8.

You instantly noticed that a c.10 body has the same absorption (4.5%) at c.
4 as one of the mid-range bodies. Ok. That is what we are talking about.
Your tolerance of absorption of your fired piece.

This is a personal decision. I do not use bodies that absorb more than
about 2% for my functional ware, but I know a lot of people do.

Will your glazes fit? Probably. Because the shrinkage is kept pretty much
at 12% for manufactured bodies. Which means that if it is a body that
shrings 12% and is a c. 6 body, or it is a body that shrinks 12% at c.6 but
is a c. 10 body you should do ok. A c. 6 glaze may work ok at c. 10 and a
c.10 glze may be ok. at c. 6. I doubt that in either case the glaze will
look exactly the same, but that is your lookout.

Absorption is not only a question of hygiene but one of crazing. The more a
body absorbs the likelier it is that the water it absorbs will kinda pry the
glaze apart. Oy, do I have other people's pots that have crazed because of
absorbed water. So that is up to you.

As always and ever I suggest you test.

The best of luck







Cat Yassin writes:

> Hola! I have a question about using a Cone 10 claybody vs. a Cone 5 when
> firing Cone 6 glazes. Sorry if its an often-asked question, I canít seem to
> access all the old Clayart discussions. For some reason about half the
> topics I try to access give me a ďPage cannot be displayed: There are too
> many ppl accesing the web at this timeĒ (but thatís a whole nuther problem
> isnít it?). Anyway, I love using B-mix. I use it to throw and handbuild
> with minimal problems. I use Cone 10 glazes AND more recently Cone 6.
> Because of this I like to stick with the same claybody so I donít end up
> with meltdowns at a higher firing range. This also gives me flexibility in
> deciding what type of glaze I want to use after I have made a piece. Am I
> asking for too much freedom in the production process this way? My concern
> is that when I use a Cone 6 glaze on a Cone 10 B-mix that the clay will be
> insufficiently vitrified for my functional work (mugs, bowls, plates). I
> have used the Cone 5 B-mix for my Cone 6 glazes and had no problems. Maybe
> Iím going to have to tinkle or get off the pot with this decision and use
> the different range clays for each glaze process, but I donít want to if I
> donít have to.
>
> Thanks in advance!
>
> -Cat Yassin
> S. Texas
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.



Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389

Be of good courage....

Mary White on mon 14 oct 02


Hi Cat--

I'm far from an expert, in fact I just did my very first electric
glaze firing a few days ago. But I was using Cone 6 glazes on Cone 10
B-mix and it worked just fine. At least the pieces appear fine and
have already been through the dishwasher a few times safely. I don't
know how to tell if they're not sufficiently vitrified, actually.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mary
on the wet west coast of British Columbia
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~





>Hola! I have a question about using a Cone 10 claybody vs. a Cone 5 when
>firing Cone 6 glazes. Sorry if its an often-asked question, I can=92t seem =
to
>access all the old Clayart discussions. For some reason about half the
>topics I try to access give me a =93Page cannot be displayed: There are too
>many ppl accessing the web at this time=94 (but that=92s a whole nuther pro=
blem
>isn=92t it?). Anyway, I love using B-mix. I use it to throw and handbuild
>with minimal problems. I use Cone 10 glazes AND more recently Cone 6.
>Because of this I like to stick with the same claybody so I don=92t end up
>with meltdowns at a higher firing range. This also gives me flexibility in
>deciding what type of glaze I want to use after I have made a piece. Am I
>asking for too much freedom in the production process this way? My concern
>is that when I use a Cone 6 glaze on a Cone 10 B-mix that the clay will be
>insufficiently vitrified for my functional work (mugs, bowls, plates). I
>have used the Cone 5 B-mix for my Cone 6 glazes and had no problems. Maybe
>I=92m going to have to tinkle or get off the pot with this decision and use
>the different range clays for each glaze process, but I don=92t want to if =
I
>don=92t have to.
>
>Thanks in advance!
>
>-Cat Yassin
>S. Texas
>
>___________________________________________________________________________=
___
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.


--

claybair on mon 14 oct 02


Hi Cat,
Your ^10 B-mix will not be vitrified at ^6.
Trust me, I tried it when I was new to clay.
I had a beautiful oil lamp leak..... bad scene.
I use ^6 B-mix now.
BTW I accidentally overfired it to ^7
and it was ok.

Gayle Bair
Bainbridge Island, WA
http://claybair.com

-----Original Message-----
From: Cat Yassin

Hola! I have a question about using a Cone 10 claybody vs. a Cone 5 when
firing Cone 6 glazes. Sorry if its an often-asked question, I canít seem to
access all the old Clayart discussions. For some reason about half the
topics I try to access give me a ďPage cannot be displayed: There are too
many ppl accessing the web at this timeĒ (but thatís a whole nuther problem
isnít it?). Anyway, I love using B-mix. I use it to throw and handbuild
with minimal problems. I use Cone 10 glazes AND more recently Cone 6.
Because of this I like to stick with the same claybody so I donít end up
with meltdowns at a higher firing range. This also gives me flexibility in
deciding what type of glaze I want to use after I have made a piece. Am I
asking for too much freedom in the production process this way? My concern
is that when I use a Cone 6 glaze on a Cone 10 B-mix that the clay will be
insufficiently vitrified for my functional work (mugs, bowls, plates). I
have used the Cone 5 B-mix for my Cone 6 glazes and had no problems. Maybe
Iím going to have to tinkle or get off the pot with this decision and use
the different range clays for each glaze process, but I donít want to if I
donít have to.

Thanks in advance!

-Cat Yassin
S. Texas

____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

Cat Yassin on tue 15 oct 02


In a message dated 10/14/2002 10:52:27 PM Central Daylight Time,
gayle@CLAYBAIR.COM writes:


> Hi Cat,
> Your ^10 B-mix will not be vitrified at ^6.
> Trust me, I tried it when I was new to clay.
> I had a beautiful oil lamp leak..... bad scene.
> I use ^6 B-mix now.
> BTW I accidentally overfired it to ^7
> and it was ok.
>
> Gayle Bair
>


Gail thanks for your reply! Thats something I was concerned about if I went
to c. 7. I had tried the c. 5 b-mix and had gone to c. 6 with no problem, but
I'm having a problem with my electric kiln and the middle fires well and the
top at least one cone lower. So, I was having to go a little higher in the
middle to get a good c. 6 at the top. Good to know the c. 5 B-mix will go to
c. 7 if it happens.

Thanks again,
-Cat
S. Texas

Ron Roy on thu 17 oct 02


Hi Cat,

You will know when you test the clay at cone 6 - it's going to leak and you
don't want that.

Think - do you want to have to mark all the cone 6 fired cone 10 clay - not
for use in microwave ovens?

There really is no choice about this - you will need different clays for
cone 10 and cone 6.

RR

>Hola! I have a question about using a Cone 10 claybody vs. a Cone 5 when
>firing Cone 6 glazes. Sorry if its an often-asked question, I can=92t seem =
to
>access all the old Clayart discussions. For some reason about half the
>topics I try to access give me a =93Page cannot be displayed: There are too
>many ppl accessing the web at this time=94 (but that=92s a whole nuther pro=
blem
>isn=92t it?). Anyway, I love using B-mix. I use it to throw and handbuild
>with minimal problems. I use Cone 10 glazes AND more recently Cone 6.
>Because of this I like to stick with the same claybody so I don=92t end up
>with meltdowns at a higher firing range. This also gives me flexibility in
>deciding what type of glaze I want to use after I have made a piece. Am I
>asking for too much freedom in the production process this way? My concern
>is that when I use a Cone 6 glaze on a Cone 10 B-mix that the clay will be
>insufficiently vitrified for my functional work (mugs, bowls, plates). I
>have used the Cone 5 B-mix for my Cone 6 glazes and had no problems. Maybe
>I=92m going to have to tinkle or get off the pot with this decision and use
>the different range clays for each glaze process, but I don=92t want to if =
I
>don=92t have to.
>
>Thanks in advance!
>
>-Cat Yassin
>S. Texas

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
=46ax: 613-475-3513=20

Ron Roy on fri 18 oct 02


Just some clarification here - I am just taking the opportunity to make a
comment that may help some understand shrinkage.

There are two kinds.

How much the clay shrinks from plastic to dry which is the wet to dry or
plastic shrinkage - normal amounts would be 5.6 to 7% as a general rule for
throwing clay. More than that and you are more likely to get warpage and
cracking during drying.

The second kind is shrinkage from melting - around 6% in a body that is
vitrified enough to not leak.

Add them together to get overall shrinkage - the usual recommendation is
12% over all for throwing clay - which also works well for most hand
building.

If a cone 10 body is only fired to cone 6 the over all shrinkage is
probably going to be less simply because the clay will be underfired and
will shrink less during firing. The wet to dry shrinkage will still be the
same in both cases.

If you are testing a clay body for shrinkage and absorbency and the
shrinkage is like 15% and the absorbency is 2% you can assume the wet to
dry shrinkage is too high - or we could say higher than it needs to be for
throwability.

If a clay body is underfired (lets say has an absorption of 5%) but the
over all shrinkage is 10% - we can assume it is not shrinking enough
because it is not melted enough so the fired shrinkage would be lower than
we expect - The wet to dry may be just fine in this case.

RR


>Will your glazes fit? Probably. Because the shrinkage is kept pretty much
>at 12% for manufactured bodies. Which means that if it is a body that
>shrings 12% and is a c. 6 body, or it is a body that shrinks 12% at c.6 but
>is a c. 10 body you should do ok. A c. 6 glaze may work ok at c. 10 and a
>c.10 glze may be ok. at c. 6. I doubt that in either case the glaze will
>look exactly the same, but that is your lookout.

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513