LJTCW@AOL.COM on fri 2 jun 00
I have been making glaze tests and in doing so, have had trouble with cobalt
oxide 'spitting" off the pot onto the shelf. Each test has about .5% cobalt
oxide. Has anyone else had this problem and what is to be done about it? I
do not ball mill the glazes and do put them through a 60 mesh testing sieve
(small). Someone told me to wait a week before using the glaze giving the
cobalt time to "melt" into the rest of the ingredients. I will test these
batches again after resieving. I am also going to mix the same tests with
cobalt carbonate, perhaps, 2%.
Louise Jenks
Cincinnati OH USA
LJTCW@AOL.COM
Robert Marshall Simpson on sat 3 jun 00
Louise
I have had the same "spitting" problem with cobalt but it hasn't been
consistent. I sieve all glazes thru either 60 or 80 mesh and fire
(electric) to ^8 with a soak. The glazes are ^10.
Kayte---in OK where the rain has finally arrived!
----- Original Message -----
From:
To:
Sent: Friday, June 02, 2000 10:27 AM
Subject: Cobalt question
> I have been making glaze tests and in doing so, have had trouble with
cobalt
> oxide 'spitting" off the pot onto the shelf. Each test has about .5%
cobalt
> oxide. Has anyone else had this problem and what is to be done about it?
I
> do not ball mill the glazes and do put them through a 60 mesh testing
sieve
> (small). Someone told me to wait a week before using the glaze giving the
> cobalt time to "melt" into the rest of the ingredients. I will test
these
> batches again after resieving. I am also going to mix the same tests
with
> cobalt carbonate, perhaps, 2%.
>
> Louise Jenks
> Cincinnati OH USA
> LJTCW@AOL.COM
>
>
____________________________________________________________________________
__
> 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.
>
Smart on sat 3 jun 00
Before firing cobalt oxide formula is Co3O4 (Black oxide), but there is a
loss of ignition and cobalt becomes CoO=2E The loss is oxygen=2E
1 molecule of Co3O4 gives 3 CoO (cobaltous oxide) and 1/2 O2 (oxygen)=2E Thi=
s
is oxygen that spits off the pot because the glaze is melted at this moment=
=2E
You can limit or stop the spitting with glaze modifications=2E The main thin=
g
to do is to increase the melting temperature of the glaze by adding china
clay or silica if possible=2E
Else you can also use your black cobalt oxide after a first firing, alone in
a crucible at high temperature, to obtain cobaltous oxide (CoO)=2E After tha=
t
you can use it without problem of spitting=2E
I hope my english is understandable=2E
Please M=2E Moderator (M=2EMel Jacobson) , let my message on clayart this ti=
me=2E
Cordialement, Smart
Smart=2EConseil
Le site Fran=E7ais d=E9di=E9 aux passionn=E9s de c=E9ramique
The French site dedicated to ceramics lovers
smart2000@wanadoo=2Efr
http://perso=2Ewanadoo=2Efr/smart2000/
----- Original Message -----
From:
To:
Sent: Friday, June 02, 2000 5:27 PM
Subject: Cobalt question
> I have been making glaze tests and in doing so, have had trouble with
cobalt
> oxide 'spitting" off the pot onto the shelf=2E Each test has about =2E5%
cobalt
> oxide=2E Has anyone else had this problem and what is to be done about it=
?
I
> do not ball mill the glazes and do put them through a 60 mesh testing
sieve
> (small)=2E Someone told me to wait a week before using the glaze giving th=
e
> cobalt time to "melt" into the rest of the ingredients=2E I will test
these
> batches again after resieving=2E I am also going to mix the same tests
with
> cobalt carbonate, perhaps, 2%=2E
>
> Louise Jenks
> Cincinnati OH USA
> LJTCW@AOL=2ECOM
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv=2Eceramics=2Eorg
>
> You may look at the archives for the list or change your subscription
> settings from http://www=2Eceramics=2Eorg/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink=2Ecom=2E
Diane G. Echlin on sat 3 jun 00
My version of Floating Blue flies off onto the shelves, too, (just the cobalt, not
the glaze) and I use the carb. I've been wondering why this happens, and also, my
studio mates are a bit annoyed with me for it, so I'm anxiously awaiting an answer.
Di
LJTCW@AOL.COM wrote:
> I have been making glaze tests and in doing so, have had trouble with cobalt
> oxide 'spitting" off the pot onto the shelf. Each test has about .5% cobalt
> oxide. Has anyone else had this problem and what is to be done about it? I
> do not ball mill the glazes and do put them through a 60 mesh testing sieve
> (small). Someone told me to wait a week before using the glaze giving the
> cobalt time to "melt" into the rest of the ingredients. I will test these
> batches again after resieving. I am also going to mix the same tests with
> cobalt carbonate, perhaps, 2%.
>
> Louise Jenks
> Cincinnati OH USA
> LJTCW@AOL.COM
>
> ______________________________________________________________________________
> 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.
Ron Roy on sun 4 jun 00
This probably has more to do with the glaze than the oxide or carbonate -
send it to me and I may be able to suggest some changes.
ronroy@total.net
RR
> I have been making glaze tests and in doing so, have had trouble with cobalt
>oxide 'spitting" off the pot onto the shelf. Each test has about .5% cobalt
>oxide. Has anyone else had this problem and what is to be done about it? I
>do not ball mill the glazes and do put them through a 60 mesh testing sieve
>(small). Someone told me to wait a week before using the glaze giving the
>cobalt time to "melt" into the rest of the ingredients. I will test these
>batches again after resieving. I am also going to mix the same tests with
>cobalt carbonate, perhaps, 2%.
>
>Louise Jenks
>Cincinnati OH USA
>LJTCW@AOL.COM
>
>______________________________________________________________________________
>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.
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
SCOX on sun 4 jun 00
Marizine blue mason stain mixed 1to 4 with gerstley borate and brushed on a
majolica base does the same thing.
LJTCW@AOL.COM wrote:
> I have been making glaze tests and in doing so, have had trouble with cobalt
> oxide 'spitting" off the pot onto the shelf. Each test has about .5% cobalt
> oxide. Has anyone else had this problem and what is to be done about it? I
> do not ball mill the glazes and do put them through a 60 mesh testing sieve
> (small). Someone told me to wait a week before using the glaze giving the
> cobalt time to "melt" into the rest of the ingredients. I will test these
> batches again after resieving. I am also going to mix the same tests with
> cobalt carbonate, perhaps, 2%.
>
> Louise Jenks
> Cincinnati OH USA
> LJTCW@AOL.COM
>
> ______________________________________________________________________________
> 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.
Maid O'Mud Pottery on wed 21 mar 01
I am running out of cobalt silicate (yes, you read right). When I
bought it in bulk about 12 years ago, I was told that it was used 1:1
for cobalt carbonate.
I am now older and wiser. This same person told me Custer and G-200
were the same, too. Glaze results showed otherwise :-(
So, before I go order something that will screw up my well tested
recipes, can anyone clue me in? Are they one and the same?
Many thanks!
--
Sam, Maid O'Mud Pottery
SW Ontario CANADA
http://www.geocities.com/paris/3110
scuttell@odyssey.on.ca
"First, the clay told me what to do
Then, I told the clay what to do
Now; we co-operate"
sam, 1994
"Effort does not always equal output"
sam, 1999
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