Chris Schafale on tue 10 feb 04
Linda,
My first question is, does she really mean "shivering"? Shivering is when
little sharp chips of clay come off the pot because the expansion is too
low.
(The glaze is too big for the pot, essentially). Is that what is happening?
I'm asking this because the expansion of this glaze is actually very high,
so
shivering would be rather unlikely. On the other hand, large amounts of
lithium are known to cause weird phenomena like this -- shivering and
crazing on the same pot, for instance.
If it really is shivering, here's a recipe she could try. I would be
willing to bet
that she will get the blue-breaking-green effect with this one, though it's
a
quite different glaze, chemically speaking. I didn't bother with the
strontium
sub because lithium is not necessary for this effect. By the way, this one
may very well craze, because all that titanium pushes the expansion up, but
it probably won't shiver, because it has a lot less lithium.
Also, tell her that, if this doesn't work, she can probably get that
green/blue
effect with a variety of different glaze bases, using the combination of
titanium and cobalt. Based on fairly extensive testing with Currie grids,
my
experience suggest that the more alumina in the glaze, the more likely that
she will get the "breaking green" effect. She probably doesn't need the
lithium at all.
New glaze for Denise to try:
BLUE BREAKING GREEN FOR DENISE
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 6 1201 deg.C. -
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Neph. Sy 11.00
EPK Kaolin 12.00
Silica 18.00
Spodumene 23.00
Whiting 6.00
Ferro Frit 3134 30.00
Titanium Dioxide 9.00
Cobalt Carbonate 1.00
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Seger Weight%
KNO 0.262 4.93%
CaO 0.567 9.17%
Li2O 0.172 1.48%
Al2O3 0.427 12.55%
B2O3 0.334 6.71%
SiO2 3.255 56.41%
TiO2 0.380 8.75%
K2O 0.028 0.75%
Na2O 0.234 4.18%
Al:Si 7.62
Expan. 7.73
ST 350.27
Ask her to report back if she tries it, please.
Chris
On 10 Feb 2004 at 8:07, Linda Pahl wrote:
> A friend of mine has a glaze that she just loves but it has a huge
> problem: it shivers on rims.
>
> I tried to help with reformulating it but I am new at this and do not
> yet know enough to undertake replacing lithium (the cause of the
> shivering?) with strontium (i.e., how much strontium to use and should
> any of the lithium be kept for color response?). She likes the color
> response she gets from cobalt with this base and has described it as a
> baby blue that breaks green.
>
> She asked if I would post the glaze in hopes that someone more
> knowledgeable might be willing to try their hand at a reformulation.
>
> Here is the recipe:
>
> Denise's Glaze, cone 6 ox.
>
> Nepy Sy ............ 35
> EPK ................... 10
> Flint .................... 20
> Gerstley .............10
> Lithium ............... 8
> Whiting ............... 8
> Titainum Diox..... 9
>
> add:
> Cobalt Carb........ 1
> Bentonite............. 2
>
> Thanks in advance for any assistance.
>
> Regards,
>
> Linda Pahl, Kew Gardens, New York
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> email: TheClosetPotter@earthlink.net
> website: http://home.earthlink.net/~jessieadair/tests/
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
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--
Light One Candle Pottery
Fuquay-Varina, North Carolina, USA
(south of Raleigh, NC)
www.lightonecandle.com
NEW email: chris at lightonecandle dot com
(insert the @ and . as appropriate)
Ivor and Olive Lewis on wed 11 feb 04
Dear Linda Pahl,
I would ask about the need for the Lithium Cabonate. Why did your
friend "Denise" include it in her recipe.
Best regards,
Ivor Lewis. Redhill, South Australia
>
> Denise's Glaze, cone 6 ox.
>
> Nepy Sy ............ 35
> EPK ................... 10
> Flint .................... 20
> Gerstley .............10
> Lithium ............... 8
> Whiting ............... 8
> Titainum Diox..... 9
>
> add:
> Cobalt Carb........ 1
> Bentonite............. 2
Ron Roy on wed 11 feb 04
Hi Linda,
This looks hopeless to me - it's not shivering because of the overall
expansion of the glaze - it's the soluble part of the lithium carb. This
happens with some bodies - the way to stop it is reduce the Lithium carb to
no more than 2%.
The problem with that is - the expansion goes way up so now it's a crazing
glaze and some of the alkalines have been replaces with CaO and Boron. The
colour will not be the same.
I have tried but I'm sure it will not be the same glaze - could be better I
suppose but not the same.
Denise's Glaze, cone 6 ox. revised by RR
Nepy Sy ............ 41.5
EPK ................... 4.5
Silica .................... 16.0
Gerstley .............17.0
Lithium ............... 2.0
>Whiting ............... 10.0
Titainum Diox..... 9.0
Total....................100.0
add:
Cobalt Carb........ 1
Bentonite............. 2
>A friend of mine has a glaze that she just loves but it has a huge
>problem: it shivers on rims.
>
>I tried to help with reformulating it but I am new at this and do not
>yet know enough to undertake replacing lithium (the cause of the
>shivering?) with strontium (i.e., how much strontium to use and should
>any of the lithium be kept for color response?). She likes the color
>response she gets from cobalt with this base and has described it as a
>baby blue that breaks green.
>
>She asked if I would post the glaze in hopes that someone more
>knowledgeable might be willing to try their hand at a reformulation.
>
>Here is the recipe:
>
>Denise's Glaze, cone 6 ox.
>
>Nepy Sy ............ 35
>EPK ................... 10
>Flint .................... 20
>Gerstley .............10
>Lithium ............... 8
>Whiting ............... 8
>Titainum Diox..... 9
>
>add:
>Cobalt Carb........ 1
>Bentonite............. 2
>
>Thanks in advance for any assistance.
>
>Regards,
>
>Linda Pahl, Kew Gardens, New York
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Linda Pahl on thu 12 feb 04
Chris,
Thank you very much for your help with this; it is much appreciated.
I found your comments and explanations very informative as I am just
beginning to understand glazes at the molecular level and there is
still so much to understand. I've recently purchased Ian Currie's
"Revealing Glazes" book and look forward to reading it, and, hopefully,
if I can follow it well enough, look forward to trying his glaze test
grids.
To answer your question about the shivering: yes, she is referring to
the splintering off of sharp pieces of fired glaze.
I've forwarded your entire post with explanations, suggestions and
recipe to Denise. She is getting ready for a crafts show this week-end
so she will very likely test the recipe you provided next week and will
report back on her results.
Thanks again!
Regards,
Linda Pahl, Kew Gardens, New York
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
email: TheClosetPotter@earthlink.net
website: http://home.earthlink.net/~jessieadair/tests/
///////////////////////////////////////////////////////////////////////
///////////////
Linda Pahl on thu 12 feb 04
> Dear Linda Pahl,
> I would ask about the need for the Lithium Cabonate. Why did your
> friend "Denise" include it in her recipe.
> Best regards,
> Ivor Lewis. Redhill, South Australia
Dear Ivor,
Denise understood that lithium can aid unusual color development when
used with copper or cobalt but wasn't fully aware of the shivering
problems that lithium can cause.
After reading Chris' response to my post, it turns out the she just may
well get the same color response from cobalt from a base glaze that
does not contain any lithium. It may well be that it is the
combination of titanium and cobalt that is giving her the blue breaking
to green effect that she likes so much.
Best,
Linda
Linda Pahl on thu 12 feb 04
Hi, Ron.
Thank you very much for reformulating Denise's glaze to reduce the
shivering. I have forwarded your post to her; she will test the new
glaze recipe next week and report back on her results.
Thanks again for your help!
Regards,
Linda
> Hi Linda,
>
> This looks hopeless to me - it's not shivering because of the overall
> expansion of the glaze - it's the soluble part of the lithium carb.
> This
> happens with some bodies - the way to stop it is reduce the Lithium
> carb to
> no more than 2%.
>
> The problem with that is - the expansion goes way up so now it's a
> crazing
> glaze and some of the alkalines have been replaces with CaO and Boron.
> The
> colour will not be the same.
>
> I have tried but I'm sure it will not be the same glaze - could be
> better I
> suppose but not the same.
>
> Denise's Glaze, cone 6 ox. revised by RR
>
> Nepy Sy ............ 41.5
> EPK ................... 4.5
> Silica .................... 16.0
> Gerstley .............17.0
> Lithium ............... 2.0
> Whiting ............... 10.0
> Titainum Diox..... 9.0
> Total....................100.0
>
> add:
> Cobalt Carb........ 1
> Bentonite............. 2
Tony Hansen on fri 13 feb 04
I am going to be really surprised to see strontium
give the same effect. I have found that when there
is lots of lithium in a special effect glaze it is
very difficult to get the same effect with another
oxide, lithium just melts so strongly compared to
other fluxes.
I did a project on an 11% lithium glaze, you can find
it in the recipe area of ceramicmaterials.info with
pictures, search for \"lithium\". I increased the boron
to make up for the reduced lithia.
I lost some of the variegation but it stopped shivering
and looks fantastic.
-------8<--------
Hi, Ron.
Thank you very much for reformulating Denise\'s glaze to reduce the
shivering. I have forwarded your post to her; she will test the new
glaze recipe next week and report back on her results.
Linda
-------
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Personal Contact Page: http://208.55.130.23/services/contact.php
Calculation/Database Software for Ceramic Industry
Tony Hansen on fri 13 feb 04
I am going to be really surprised to see strontium
give the same effect. I have found that when there
is lots of lithium in a special effect glaze it is
very difficult to get the same effect with another
oxide, lithium just melts so strongly compared to
other fluxes.
I did a project on an 11% lithium glaze, you can find
it in the recipe area of ceramicmaterials.info with
pictures, search for \"lithium\". I increased the boron
to make up for the reduced lithia.
I lost some of the variegation but it stopped shivering
and looks fantastic.
-------8<--------
Hi, Ron.
Thank you very much for reformulating Denise\'s glaze to reduce the
shivering. I have forwarded your post to her; she will test the new
glaze recipe next week and report back on her results.
Linda
-------
You can update your personal and affiliation info on our website:
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Tony Hansen, http://digitalfire.com
Personal Contact Page: http://208.55.130.23/services/contact.php?pwd=gubmumam
Calculation/Database Software for Ceramic Industry
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