Knox Steinbrecher on mon 2 aug 99
So are you saying I can substitute Colemanite for Gerstley Borate and
eliminate the "pudding" results I have been getting in my latest glaze batch
???
My two favorite base glazes are :
# 1 Base
64.2 Volcanic Ash
35.8 Gerstley Borate
#2 Base
50 Gerstley Borate
17.5 EPK
32.5 Flint
I fire to cone 6 oxidation and have found theses bases produce great results.
I normally use Standard 112 clay or Golden Buff SP from Great Lakes Clay in
Illinois.
The last batch I made is waaaay too thick, even with Darvan 7 added.
Floating Blue was also too thick this time and it has Gerstley Borate.
So , can I sub colemanite equally and get the same results???
BTW...thanks to Clayart and RR (?) I have slowed my bisque firing down.
Didn't know it was too fast...and the results are fabulous. Everything is
pink, pink,pink and glazes are nicer too. Thanks a jillion !!!!!!
knox in Atlanta .....
tmartens on wed 4 aug 99
You can sub Colemanite for Gerstley, but not knowing the source of
your Colemanite, I would like to throw in my two cents worth.
Our Colemanite (South Africa) comes from Turkey and is
contaminated with Gypsum, I have watched that damn stuff get up
and walk off my pots! Personally, I would rather try and find a frit sub,
that is if you really hate the Gerstley. I love it, can't get it here and am
deeply grateful to the Clayarters who trade all sorts of odd things with
me for Gerstley.
Toni Martens Durban South Africa
> ----------------------------Original message----------------------------
> So are you saying I can substitute Colemanite for Gerstley Borate and
> eliminate the "pudding" results I have been getting in my latest glaze batch
> ???
>
> My two favorite base glazes are :
>
> # 1 Base
> 64.2 Volcanic Ash
> 35.8 Gerstley Borate
>
>
> #2 Base
> 50 Gerstley Borate
> 17.5 EPK
> 32.5 Flint
>
>
> I fire to cone 6 oxidation and have found theses bases produce great results.
> I normally use Standard 112 clay or Golden Buff SP from Great Lakes Clay in
> Illinois.
> The last batch I made is waaaay too thick, even with Darvan 7 added.
> Floating Blue was also too thick this time and it has Gerstley Borate.
>
> So , can I sub colemanite equally and get the same results???
>
> BTW...thanks to Clayart and RR (?) I have slowed my bisque firing down.
> Didn't know it was too fast...and the results are fabulous. Everything is
> pink, pink,pink and glazes are nicer too. Thanks a jillion !!!!!!
>
>
> knox in Atlanta .....
Carenza Hayhoe on wed 4 aug 99
I read your question about colmenite/gerstley borate with a sinking heart.
I was given some gerstley borate many years ago by an american friend and
had some super results with it. At the time you couldn't buy it in the UK
so I tried substituting colmanite - result? The glaze spat off the pot and
lay in a pool on the kiln shelf. Hope you have more success - I would love
to hear if substituting works for you - Carenza.
The oppressive hot weather we've been having has broken at last with a
tremendous thunder storm and torrential rain - wonderful!
At 09:37 02/08/99 EDT, Knox Steinbrecher wrote:
>----------------------------Original message----------------------------
>So are you saying I can substitute Colemanite for Gerstley Borate and
>eliminate the "pudding" results I have been getting in my latest glaze batch
>???
>
>My two favorite base glazes are :
>
># 1 Base
>64.2 Volcanic Ash
>35.8 Gerstley Borate
>
>
>#2 Base
>50 Gerstley Borate
>17.5 EPK
>32.5 Flint
>
>
>I fire to cone 6 oxidation and have found theses bases produce great results.
> I normally use Standard 112 clay or Golden Buff SP from Great Lakes Clay in
>Illinois.
>The last batch I made is waaaay too thick, even with Darvan 7 added.
>Floating Blue was also too thick this time and it has Gerstley Borate.
>
>So , can I sub colemanite equally and get the same results???
>
>BTW...thanks to Clayart and RR (?) I have slowed my bisque firing down.
>Didn't know it was too fast...and the results are fabulous. Everything is
>pink, pink,pink and glazes are nicer too. Thanks a jillion !!!!!!
>
>
>knox in Atlanta .....
>
>
>
June Perry on wed 4 aug 99
Both the colemanite and gerstley are sources of unfritted boron, so you'll
get flocculation with either one. The only way to avoid the "pudding " is to
use the glaze in a relatively short period of time (a few months) before it
has a chance to flocculate, or reformulate your recipe and replace most or
all of the gerstley with a boron frit.
Regards,
June
Knox Steinbrecher on fri 6 aug 99
Hi June
This particular batch of glaze flocculated instantly, that's why the concern.
Guess I simply got a nasty batch this time as I have been using it for
years with no trouble.
knox
June Perry on sat 7 aug 99
In a message dated 8/6/1999 8:25:15 AM Pacific Daylight Time, Knox113@aol.com
writes:
<< Hi June
This particular batch of glaze flocculated instantly, that's why the concern.
Guess I simply got a nasty batch this time as I have been using it for
years with no trouble.
knox >>
That is very strange! Are you sure it's gerstley, or gerstley that you put in
the batch??? Have you done a melt test with the pure material to check it
against what you have? You might want to see if you can get a breakdown from
the supplier and ask if anyone else has had a problem with the material
recently.
It will be interesting to see what others say about the possibility of the
material flocculating instantly. Something doesn't sound right. :-(
Regards,
June
Knox Steinbrecher on sun 8 aug 99
Hi June,
No melt test as what I have (had) is used up and gone. I assumed it was the
gerstley as the two glazes I mixed that behaved in the same manner both
contained gerstley. I met another potter a few weeks later at a show who
commenteed that he had the same thing happen to him. Also gerstley, also the
same supplier.
I am managing it now. After adding Darvan 7, the consistancy is better on
one glaze and the other I will simply use up and not worry about it. That
one has a high volcanic ash content and gets thick anyway.
I appreciate your suggestion of doing a melt test and if I have trouble with
the 50 pound sack of gerstley that i recently purchased, I'll do that for
sure. Only question then becomes.....what do I do after the melt test?????
knox...in Atlanta....
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