Malone & Dean McRaine on wed 29 oct 97
Aloha all: I think you've heard this one before. I have a glaze that I've
been using for 10 years with no problems. In that time I've been through
several orders of materials and changes of circumstance. You know where
this is going, my last firing I began using a new batch of glaze that I
mixed a few days ago. Instead of a matt red-brown with ochre highlights I
got something that looks more like a gloss dark amber ash glaze. Total
disaster! Here's the recipe:
Vermillion Brick Red ^9-10 Oxidation (I fire in an electric kiln but I think
this works well in reduction too)
50 Cornwall Stone
25 Whiting
24 EPK
1 Bentonite
8 Red Iron Oxide
3 Wood Ash (optional)
So I am asking myself, what is different form the last time I made this glaze?
The Cornwall Stone, EPK, Bentonite, iron, and wood ash are all from the same
batches that I used to mix my last bucket of glaze. My firing was perfect-
^10 at 3 o'clock top and bottom. Only the Whiting was different. I just
moved and have had several buckets of Whiting from different sources. I used
a different one. In the confusion of moving home and studio I apparently
have made an error, a mistake, a faux pas, flubbed eutectically, dropped the
ball, as it were... So here are the possibilities as I see them:
1. The Whiting was so different it radically altered the glaze. This is one
question I want to ask the group, is it possible that this new material
could be so different from my previous supply that it could cause this
drastic problem?
2. I labelled the bucket wrong and I've really got something else, possibly
a frit, that I think is Whiting. If so, how can I find out what it is,
cause I've got a lot?
3. I mixed the glaze wrong, doubled the Whiting or the ash or?
4. I'm a Compleat Idiot and should get a job at Macdonald's and forget about
clay altogether.
If you have any ideas please help me out.
I'll be mixing tests and trying to figure out where I went wrong in the next
few days. I'd appreciate a direct e-mail as well as a clayart posting if you
have any help to offer.
Thanks
Dean. From Kauai, looking very much like paradise, sunny warm and breezy.
Unruly JuliE on thu 30 oct 97
Dean,
Any differences in your water? I know that city water and country
will make a glaze come out different. All the chemicals they put
in city water, and then wether the water is hard (calcium?) or if
you are using a water softner (salt).
Most of the potters I know use distilled water to ensure the same
(??) water every time.
JuliE in Michigan where we are getting a reprise from the cold but
not the rain.
LINDA BLOSSOM on thu 30 oct 97
Dean, this is a problem that I'll bet most of us share. I would begin by
comparing what is in those buckets with what I know to be whiting. I might
do volume and weight comparisons also. Then if there was no visible
differences (all those white materials look a lot alike) I would make
small batches using each one of the buckets and go to a friend and get some
whiting that was not suspect. Sounds like something I did last year when
Laguna mislabeled a ten pound bad of a material. Taught me to always buy
unopened bags.
Linda Blossom
2366 Slaterville Rd.
Ithaca, NY 14850
607-539-7912
blossom@lightlink.com
http://www.artscape.com
Grimmer on fri 31 oct 97
Dean,
That glaze looks a lot like a glaze I use that has LOADS of calcia.
Chemically, it's very near a fake ash glaze. The glaze I use will
sometimes web up and run a bit. I guess I always considered that a
bonus, especially in a gas kiln (ie no salt or wood).
It could be, as Louis Katz suggested, you were using something closer to
dolomite before. Now you have real Calcium Carb, and the glaze goes all
runny on you.
Ever try your base with copper as the colorant?
steve grimmer
marion illinois
Dean McRaine wrote:
> Aloha all: I think you've heard this one before. I have a glaze that I've
> been using for 10 years with no problems. In that time I've been through
> several orders of materials and changes of circumstance. You know where
> this is going, my last firing I began using a new batch of glaze that I
> mixed a few days ago. Instead of a matt red-brown with ochre highlights I
> got something that looks more like a gloss dark amber ash glaze. Total
> disaster! Here's the recipe:
>
> Vermillion Brick Red ^9-10 Oxidation (I fire in an electric kiln but I think
> this works well in reduction too)
>
> 50 Cornwall Stone
> 25 Whiting
> 24 EPK
> 1 Bentonite
> 8 Red Iron Oxide
> 3 Wood Ash (optional)
>
> So I am asking myself, what is different form the last time I made this glaze?
> The Cornwall Stone, EPK, Bentonite, iron, and wood ash are all from the same
> batches that I used to mix my last bucket of glaze. My firing was perfect-
> ^10 at 3 o'clock top and bottom. Only the Whiting was different. I just
> moved and have had several buckets of Whiting from different sources. I used
> a different one. In the confusion of moving home and studio I apparently
> have made an error, a mistake, a faux pas, flubbed eutectically, dropped the
> ball, as it were... So here are the possibilities as I see them:
>
> 1. The Whiting was so different it radically altered the glaze. This is one
> question I want to ask the group, is it possible that this new material
> could be so different from my previous supply that it could cause this
> drastic problem?
>
> 2. I labelled the bucket wrong and I've really got something else, possibly
> a frit, that I think is Whiting. If so, how can I find out what it is,
> cause I've got a lot?
>
> 3. I mixed the glaze wrong, doubled the Whiting or the ash or?
>
> 4. I'm a Compleat Idiot and should get a job at Macdonald's and forget about
> clay altogether.
>
> If you have any ideas please help me out.
> I'll be mixing tests and trying to figure out where I went wrong in the next
> few days. I'd appreciate a direct e-mail as well as a clayart posting if you
> have any help to offer.
>
> Thanks
> Dean. From Kauai, looking very much like paradise, sunny warm and breezy.
stevemills on fri 31 oct 97
Two thoughts,
note 1 yes whiting is limestone, a different seam/quarry/treatment plant
could possibly make that difference.
if you suspect fritt do a button test (very small amount mixed into a
ball with water on a tile) and fire it that will tell you quite a lot.
As suppliers our cardinal rule is consistancy in materials supply(er)
else chaos results.
Steve Mi
Bathlls
In message , Malone & Dean McRaine writes
>----------------------------Original message----------------------------
>Aloha all: I think you've heard this one before. I have a glaze that I've
>been using for 10 years with no problems. In that time I've been through
>several orders of materials and changes of circumstance. You know where
>this is going, my last firing I began using a new batch of glaze that I
>mixed a few days ago. Instead of a matt red-brown with ochre highlights I
>got something that looks more like a gloss dark amber ash glaze. Total
>disaster! Here's the recipe:
>
>Vermillion Brick Red ^9-10 Oxidation (I fire in an electric kiln but I think
>this works well in reduction too)
>
>50 Cornwall Stone
>25 Whiting
>24 EPK
>1 Bentonite
>8 Red Iron Oxide
>3 Wood Ash (optional)
>
>So I am asking myself, what is different form the last time I made this glaze?
>The Cornwall Stone, EPK, Bentonite, iron, and wood ash are all from the same
>batches that I used to mix my last bucket of glaze. My firing was perfect-
>^10 at 3 o'clock top and bottom. Only the Whiting was different. I just
>moved and have had several buckets of Whiting from different sources. I used
>a different one. In the confusion of moving home and studio I apparently
>have made an error, a mistake, a faux pas, flubbed eutectically, dropped the
>ball, as it were... So here are the possibilities as I see them:
>
>1. The Whiting was so different it radically altered the glaze. This is one
>question I want to ask the group, is it possible that this new material
>could be so different from my previous supply that it could cause this
>drastic problem?
>
>2. I labelled the bucket wrong and I've really got something else, possibly
>a frit, that I think is Whiting. If so, how can I find out what it is,
>cause I've got a lot?
>
>3. I mixed the glaze wrong, doubled the Whiting or the ash or?
>
>4. I'm a Compleat Idiot and should get a job at Macdonald's and forget about
>clay altogether.
>
>If you have any ideas please help me out.
>I'll be mixing tests and trying to figure out where I went wrong in the next
>few days. I'd appreciate a direct e-mail as well as a clayart posting if you
>have any help to offer.
>
>Thanks
>Dean. From Kauai, looking very much like paradise, sunny warm and breezy.
>
--
Steve Mills
@Bath Potters Supplies
Dorset Close
Bath
BA2 3RF
UK
Tel:(44) (0)1225 337046
Fax:(44) (0)1225 462712
jims@connect.ab.ca on sat 1 nov 97
Dean,
Before you go tossing potentially suspect materials away... your first
step should probably be to remix a small new test batch of your glaze "with
the same materials" you previously used (if you haven't already done so).
This way you'll at least be able to know that it wasn't (or was) simply
an error in weighing out the original batch. If it still bombs, then it's
on to materals testing as others have suggested. Good luck.
Cheers... Jim
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
jims@connect.ab.ca Edmonton/Alberta/Canada
http://www.connect.ab.ca/~jims
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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