Dwiggins, Sandra (NCI) on tue 20 jul 99
Hello Claypeople--
I have great need of a translucent deep green cone 6 ox. glaze. We've tried
numerous cone6 greens, at the studio where I teach, but none have fit the bill.
The most important feature is some translucency and depth. Most of the greens
we've tried are that drab chrome green without any character. Help!!
Question: The lab monitors at the community studio where I teach mix the
glazes. Lately, the glazes have not been keeping the heavier materials in
suspension, and as soon as they are mixed up, the stuff sinks to the bottom of
the glaze bucket. The monitors swear that they are putting bentonite in. There
are several 5 gallon containers of glaze that are practically useless because of
this sinking. Is it possible to add the Bentonite as a gel, the way Mel
suggests, at this point, then sieve the glaze again--hoping the stuff will stay
in suspension? Should we try some Epsom salts instead? Throwing away the
glazes is a major financial loss....but if we have to we will. Help---Ron,
Mel, anybody?
Sandy
Sandra Dwiggins
Sandra Dwiggins
Technical Information Specialist
Office of Cancer Information, Communication and Education
National Cancer Institute
National Institutes of Health
e-mail: sdwiggin@exchange.nih.gov
fax:301-480-8105
phone: 301-496-7406
Kim Marie on wed 21 jul 99
I use a base glaze and add 5% copper carbonate. I get a rich avocado green.
it is a gloss though. If you'd like the recipe, I'd be glad to send.
kim
kmarie@odyssey.net
-----Original Message-----
From: Dwiggins, Sandra (NCI)
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, July 20, 1999 10:25 AM
Subject: Glaze need/ Suspension Question
----------------------------Original message----------------------------
Hello Claypeople--
I have great need of a translucent deep green cone 6 ox. glaze. We've
tried
numerous cone6 greens, at the studio where I teach, but none have fit the
bill.
The most important feature is some translucency and depth. Most of the
greens
we've tried are that drab chrome green without any character. Help!!
Question: The lab monitors at the community studio where I teach mix the
glazes. Lately, the glazes have not been keeping the heavier materials in
suspension, and as soon as they are mixed up, the stuff sinks to the bottom
of
the glaze bucket. The monitors swear that they are putting bentonite in.
There
are several 5 gallon containers of glaze that are practically useless
because of
this sinking. Is it possible to add the Bentonite as a gel, the way Mel
suggests, at this point, then sieve the glaze again--hoping the stuff will
stay
in suspension? Should we try some Epsom salts instead? Throwing away
the
glazes is a major financial loss....but if we have to we will. Help---Ron,
Mel, anybody?
Sandy
Sandra Dwiggins
Sandra Dwiggins
Technical Information Specialist
Office of Cancer Information, Communication and Education
National Cancer Institute
National Institutes of Health
e-mail: sdwiggin@exchange.nih.gov
fax:301-480-8105
phone: 301-496-7406
amy parker on wed 21 jul 99
At 10:25 AM 7/20/99 EDT, you wrote:
>----------------------------Original message----------------------------
>Hello Claypeople--
>I have great need of a translucent deep green cone 6 ox. glaze. We've tried
>numerous cone6 greens, at the studio where I teach, but none have fit the bill.
>The most important feature is some translucency and depth. Most of the greens
>we've tried are that drab chrome green without any character. Help!!
Sandy - try adding .5 % of black stain to one of the green glazes that you
otherwise like. I used this with 1 % copper carb, trying for faux celadon -
meant to add .2% (oops) - and got what I would term a "dark spruce green"
that is still translucent. May work with the chrome as well.
Amy in Hotlanta, frantically mixing glazes while the kids are at camp!
amy parker Lithonia, GA
amyp@sd-software.com
Chris Schafale on wed 21 jul 99
Hi Sandy,
If you get a great green glaze off-list, please pass it on!
Re: the sinking glazes, there's no reason you couldn't add more
bentonite in the liquid form, but it seems that you should figure
out why this is happening, if the recipes are being followed
correctly, and the glazes haven't behaved this way before. One
thought that occurs to me is that perhaps the "bentonite" they're
putting in isn't really bentonite -- we had a bizarre situation with
a mislabelled bag once that makes me wonder about this. To find out,
try mixing some up with a smallish amount of water -- if it doesn't
swell and turn into unmanageable goo, it may not be bentonite. The
other thing I wonder is whether some other ingredient has changed --
do the offending glazes share any other material? Could there be
something soluble that is deflocculating the glazes and making them
settle rapidly?
Good luck,
Chris
> ----------------------------Original message----------------------------
> Hello Claypeople--
> I have great need of a translucent deep green cone 6 ox. glaze. We've tried
> numerous cone6 greens, at the studio where I teach, but none have fit the bill
> The most important feature is some translucency and depth. Most of the greens
> we've tried are that drab chrome green without any character. Help!!
>
> Question: The lab monitors at the community studio where I teach mix the
> glazes. Lately, the glazes have not been keeping the heavier materials in
> suspension, and as soon as they are mixed up, the stuff sinks to the bottom of
> the glaze bucket. The monitors swear that they are putting bentonite in. The
> are several 5 gallon containers of glaze that are practically useless because
> this sinking. Is it possible to add the Bentonite as a gel, the way Mel
> suggests, at this point, then sieve the glaze again--hoping the stuff will sta
> in suspension? Should we try some Epsom salts instead? Throwing away the
> glazes is a major financial loss....but if we have to we will. Help---Ron,
> Mel, anybody?
> Sandy
>
> Sandra Dwiggins
> Sandra Dwiggins
> Technical Information Specialist
> Office of Cancer Information, Communication and Education
> National Cancer Institute
> National Institutes of Health
> e-mail: sdwiggin@exchange.nih.gov
> fax:301-480-8105
> phone: 301-496-7406
>
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
Michael Banks on wed 21 jul 99
A number of cone 6 translucent greens have been posted on Clayart in the
last twelve months (emerald green, floating green etc). The best
transmission (transparent) greens in my opinion tend to be based on high
(+3%) copper oxide contents in a low silica, high flux recipe (e.g. emerald
green). But they're not durable and will release copper to acid foods
(fruit juice, coffee, pickles etc), so are totally unsuitable for anything
other than decorative items. On the right item they look great, though
usually craze like mad :D (!)
As a teacher you may have to ask yourself whether subsequent users in your
community studio will adhere to these restrictions, if you introduce such a
glaze.
Question Two: Just adding bentonite to, say a frit-rich glaze, will often
on its own, not suspend the glaze ingredients permanently. The slop must
also be kept in a flocculated condition by judicious use of Epsom salts or
other flocculants. Frits, nepheline syenite, soda feldspar and other
slightly soluble materials in some glazes slowly release sodium ions which
deflocculate the suspender (e.g. bentonite) making it ineffective.
Additions of flocculent may have to be made on a regular basis to counteract
this. The other remedy is to add a lot of fresh water every now and then,
settle and decant the excess to flush out the soluble soda. This sounds like
a lot of work, but if done every 12 months or so (if your glaze lasts that
long) will prevent an associated problem, the solidification or concreting
of settled glaze ingredients caused by crystallisation of sodium salts.
Michael Banks,
Nelson,
New Zealand
> ----------------------------Original message----------------------------
> Hello Claypeople--
> I have great need of a translucent deep green cone 6 ox. glaze. We've
tried
> numerous cone6 greens, at the studio where I teach, but none have fit the
bill.
> The most important feature is some translucency and depth. Most of the
greens
> we've tried are that drab chrome green without any character. Help!!
>
> Question: The lab monitors at the community studio where I teach mix the
> glazes. Lately, the glazes have not been keeping the heavier materials in
> suspension, and as soon as they are mixed up, the stuff sinks to the
bottom of
> the glaze bucket. The monitors swear that they are putting bentonite in.
There
> are several 5 gallon containers of glaze that are practically useless
because of
> this sinking. Is it possible to add the Bentonite as a gel, the way Mel
> suggests, at this point, then sieve the glaze again--hoping the stuff will
stay
> in suspension? Should we try some Epsom salts instead? Throwing away
the
> glazes is a major financial loss....but if we have to we will.
Help---Ron,
> Mel, anybody?
> Sandy
>
> Sandra Dwiggins
John Rodgers on wed 21 jul 99
-- [ From: John Rodgers * EMC.Ver #2.5.02 ] --
Sandra, at our shop in NM we routinely add sodium silicate or epsom salts,
depending on which way we need to go, to keep materials in suspension, and
get best flow for use in a spray gun. A little cmc is added to aid the glaze
in adherring to the surface it is being sprayed on.
For your problem a little epsom salts will probably do the trick. It will
tend to thicken the glaze. Just remember, a little goes a long way. And if
you add sodium silicate, the materials will settle out instantly if you get
to much.
Another thing to check is the specific gravity. If it is to low, that
probably means to much water, and the materials will settle out. For our use
, a spg of 1.60 is ideal, but glazes can vary, and the number we use as
optimum was arrived at by experimentation with the glazes we use in
production.
Good luck.
John Rodgers in NM
-------- REPLY, Original message follows --------
Date: Tuesday, 20-Jul-99 10:25 AM
From: Dwiggins, Sandra \ Internet: (sdwiggin@exchange.nih.gov)
To: Clayart \ Internet: (clayart@lsv.uky.edu)
Subject: Glaze need/ Suspension Question
----------------------------Original message----------------------------
Hello Claypeople--
I have great need of a translucent deep green cone 6 ox. glaze. We've
tried numerous cone6 greens, at the studio where I teach, but none have fit
the bill. The most important feature is some translucency and depth. Most
of the greens we've tried are that drab chrome green without any character.
Help!!
Question: The lab monitors at the community studio where I teach mix the
glazes. Lately, the glazes have not been keeping the heavier materials in
suspension, and as soon as they are mixed up, the stuff sinks to the bottom
of the glaze bucket. The monitors swear that they are putting bentonite in.
There are several 5 gallon containers of glaze that are practically useless
because of this sinking. Is it possible to add the Bentonite as a gel, the
way Mel suggests, at this point, then sieve the glaze again--hoping the
stuff will stay in suspension? Should we try some Epsom salts instead?
Throwing away the glazes is a major financial loss....but if we have to we
will. Help---Ron, Mel, anybody? Sandy
Sandra Dwiggins
Sandra Dwiggins
Technical Information Specialist
Office of Cancer Information, Communication and Education
National Cancer Institute
National Institutes of Health
e-mail: sdwiggin@exchange.nih.gov
fax:301-480-8105
phone: 301-496-7406
-------- REPLY, End of original message --------
Alison Hamilton on thu 22 jul 99
It is with great trepidation that I am posting this glaze recipe. The last time
posted a recipe - well, let's just say it did not survive the scrutiny of
The-One-Who-Knows (a.k.a. Ron Roy).
Posting the recipe changed my priorities which resulted in a huge detour in my
pottery work; Ron's comments convinced me (kicking and screaming) that I needed
know more about glaze calculation. It has not been a smooth path, but (drum rol
please) here's a recipe that should pass muster, especially since half of it is
his! (and if it doesn't work, blame my half of the recipe!) :)
Ron kindly gave me a revision to a green glaze of mine that was crazing and I al
made a revision. This recipe is a blend of these two revisions. I tested it fo
the first time at Ron's course at Canadore College a few weeks ago and another
student commented that it looked pretty close to a reduction celadon. Let me kn
what you think.
This is for Cone 6, oxidation.
Ron-Ali's Green
===============
DOLOMITE............ 9.50 9.31%
G-200 FELDSPAR G200. 38.50 37.75%
SILICA.............. 17.00 16.67%
F12................. 14.00 13.73%
ZINC OXIDE.......... 2.00 1.96%
BELL DARK BALL CLAY. 7.00 6.86%
TALC................ 7.00 6.86%
Tin Oxide........... 2.00 1.96%
Manganese Dioxide... 2.00 1.96%
*Copper carbonate.... 2.00 1.96%
BENTONITE........... 1.00 0.98%
========
102.00
CaO 0.36* 7.12%
MnO2 0.07 2.13%
MgO 0.31* 4.36%
K2O 0.13* 4.40%
Na2O 0.13* 2.84%
ZnO 0.07* 2.13%
Fe2O3 0.00 0.21%
TIO2 0.00 0.11%
B2O3 0.14* 3.53%
AL2O3 0.28 10.00%
SiO2 2.88 61.04%
SnO2 .04 2.12%
COST/KG 1.90
Si:Al 10.38
EXPAN 484.95
Thanks, Ron.
Alison Hamilton
Trout Lake
Dorset, ON
Evan Dresel on thu 22 jul 99
This is interesting because I have just been looking at a ^6 green glaze
published by Richard Zakin. In some ways it is similar to the Emerald
Green
+++++++++++++++++++++++++++++++++++++
+++ Zakin Emerald Transparent +++
+++++++++++++++++++++++++++++++++++++
Range: ^6
Firing type: Oxidation
Color: Green
Surface: Matt
Date: 07/20/99
Nepheline syenite 51
Wollastonite 14
Gerstley borate 22
Ball clay 8
Titanium dioxide 2
Zinc oxide 3
--------
100
Copper carbonate 3
This glaze also looks short on silica and seems like it will craze like
heck. (guess I'll find out when I fire my test). What I found
interesting, was Zakin's comment that the titanium increases the
durability.
I checked Hammer and Hammer who seem to confirm this: "titanium oxide
dissolved in a glaze gives a stabilizing effect to the glass structure".
It "hardens the glaze making it more refractory..." They also say
titanium can decrease the solubility of lead in lead frits but don't
address other metals. Obviously if copper leaching is a concern you
should test. Only about 1 % of titanium dioxide is soluble in the
silica glass, greater amounts will produce micro crystals and opacity.
If anyone has more info on the effects of titanium dioxide in glazes
that confirms or refutes this, I'd be interested. In the mean time it
seems like an interesting thing to consider and test.
-- Evan in W. Richland WA who had a kind of close call with an exploding
fertilizer tanker truck. I was well out of the shrapnel zone but, boy
it was loud. No one was hurt, luckily.
ps Robert Wilt: Your cheque is in the mail!
Michael Banks wrote:
>
> ----------------------------Original Message--------------------
> A number of cone 6 translucent greens have been posted on Clayart in the
> last twelve months (emerald green, floating green etc). The best
> transmission (transparent) greens in my opinion tend to be based on high
> (+3%) copper oxide contents in a low silica, high flux recipe (e.g. emerald
> green). But they're not durable and will release copper to acid foods
> (fruit juice, coffee, pickles etc), so are totally unsuitable for anything
> other than decorative items. On the right item they look great, though
> usually craze like mad :D (!)
snip...
>
> Michael Banks,
> Nelson,
> New Zealand
Sondra Karipides on fri 23 jul 99
This glaze which was just posted, sounds interesting, but what is
F12? I have never come across it before. Thanks again, Clayarters
for all this wealth of information you so generously share with us
all!
>
>Ron-Ali's Green C/6
>===============
> DOLOMITE............ 9.50 9.31%
> G-200 FELDSPAR G200. 38.50 37.75%
> SILICA.............. 17.00 16.67%
> F12................. 14.00 13.73%
> ZINC OXIDE.......... 2.00 1.96%
> BELL DARK BALL CLAY. 7.00 6.86%
> TALC................ 7.00 6.86%
> Tin Oxide........... 2.00 1.96%
> Manganese Dioxide... 2.00 1.96%
>*Copper carbonate.... 2.00 1.96%
> BENTONITE........... 1.00 0.98%
Sondra
Emily Muench on fri 23 jul 99
Ali or Ron,
What's F12 and Bell Dark Ball clay ? if not available in the US, any
substitutions?
Thanks, Em
Ron Roy on sat 24 jul 99
Hi Em,
I already explained about the F12 - I can almost say any ball clay - but
that would not be right - lets say OM#4 or Tenn #9 - If you calculate and
have the analysis of the ball clay you have - then here is a typical
analysis of Bell Dark - my favorite ball.
SiO2 - 58.3
Al2O3 - 27.7
Fe2O3 - 1.0
TiO2 - 1.5
CaO - 0.3
MgO - 0.2
K2O - 1.0
Na2O - 0.3
LOI - 12.60
Total - 100.0
All clay analysis have a total of less than 100 because some of the trace
oxides are not included - I have rounded these off in this case - they will
be more than close enough to the real thing.
Why is it my fav ball clay? Well it has a very consistant record over the
20 years we have been testing it. It is one of the lightest burning ball
clays, has very small grain size and high shrinkage - and best of all has a
high modulus of rupture which makes clays stronger in the dry state and
adds toughness to glazes when dry.
It does have a high carbon content - that means better plasticity but watch
out if you like the idea of fast firing your bisque.
Why is it called "dark" when it is a light burning clay - cause the carbon
in the unfired clay makes it look darker than most clays - but that fires
out.
>----------------------------Original message----------------------------
>Ali or Ron,
>
>What's F12 and Bell Dark Ball clay ? if not available in the US, any
>substitutions?
>
> Thanks, Em
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Alison Hamilton on sat 24 jul 99
Fusion F12 is a substitute for Frit 3134 which my local pottery supply place
is no longer able to provide. They're pretty similar although the numbers
I'm giving you don't make them look that similar - I think my Frit 3134
analysis may not be up to date. Hopefully someone can give you more
accurate information if this isn't right.
F12 Frit 3134
CaO 18.1% 20.1%
Na2O 10.4% 10.3%
B2O3 26.7% 23.1%
SiO2 43.6% 46.5%
Al2O3 1.3% 0%?
Hope this helps!
Alison
Trout Lake
Dorset, ON
Sondra Karipides wrote:
> ----------------------------Original message----------------------------
> This glaze which was just posted, sounds interesting, but what is
> F12? I have never come across it before. Thanks again, Clayarters
> for all this wealth of information you so generously share with us
> all!
> >
> >Ron-Ali's Green C/6
> >===============
> > DOLOMITE............ 9.50 9.31%
> > G-200 FELDSPAR G200. 38.50 37.75%
> > SILICA.............. 17.00 16.67%
> > F12................. 14.00 13.73%
> > ZINC OXIDE.......... 2.00 1.96%
> > BELL DARK BALL CLAY. 7.00 6.86%
> > TALC................ 7.00 6.86%
> > Tin Oxide........... 2.00 1.96%
> > Manganese Dioxide... 2.00 1.96%
> >*Copper carbonate.... 2.00 1.96%
> > BENTONITE........... 1.00 0.98%
>
> Sondra
Alison Hamilton on sat 24 jul 99
Emily,
Bell Dark is a type of ball clay - I like to describe ball clays as poor
cousins of kaolins, since not only does ball clay have kaolinite (pure clay
mineral), it also has free silica and some other oxides in it (which act as
fluxes). Okay, I admit it - I am now showing off to an audience of
thousands, that I know how to plagiarize the Hamers'!
Anyway, I went through the analyses that I have of ball clays (there are
many different kinds) and the ones that seem the closest to Bell Dark are
OM#4, Tennessee #9 and Thomas. BUT, I am on very shaky ground here since I
have Bell Dark and have never had to substitute it! :)
Hopefully someone will step in and give you some more accurate information
on what the best substitute is (and correct me in front of an audience of
thousands....)
Alison Hamilton
Trout Lake
Dorset, ON
Emily Muench wrote:
> ----------------------------Original message----------------------------
> Ali or Ron,
>
> What's F12 and Bell Dark Ball clay ? if not available in the US, any
> substitutions?
>
> Thanks, Em
Tom Buck on sun 25 jul 99
Well, Ali
since you asked, I looked up my datasheet on ballclays (Ron Roy actually
prepared it), and you are right on:
OM#4 Bell D Tenn#9 SGP#1
SiO2% 55.2 58.3 55.5 57.7
Al2O3% 27.9 27.7 30.0 27.9
The trace amounts of other ingredients run roughly the same. The Loss on
Ignition runs 10.2% (SGP) to 12.6% (OM#4).
So in amounts of 10-15 wt% per glaze batch, the four BCs are
essntially the same, and it would be most difficult to detect any
differences (without special instruments/devices).
Tom Buck
)
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
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