search  current discussion  categories  safety - misc 

safe glazes for a university student pottery studio

updated sun 1 apr 07

 

Donna Kat on thu 29 mar 07


I would like to go to our administrator and say =93these are our current
glazes. These are the ones I would not consider good for a
student/hobbyist environment and these are ones that are good to keep.=94
Before doing so I want to make sure what I am saying is correct.

Schran=92s Orange // a good stable glaze I think =96 satin matt creamy oran=
ge

Dolomite 1750
Alkalies .178 Fluxes 1
Spodumene 1750 Al2O3 .321
Gerstley 800 B2O3 .134
Talc 350 SiO2 2.624
F 3134 500
8.167:1 Si:Al
Kona F4 500
EPK 100
Flint 2500

Spanish RIO 150
Yellow Ochre 250
Tine Oxide 350
Bentonite 150


Speckled Blue // questionable =96 low on silica and uses Manganese =96 I
would like to eliminate this glaze but I can=92t say why

Kona F4 3400 .258:1
Alkalies:Fluxes
Neph Sye 1700 Al2O3 .424
Whiting 1260 SiO2 2.115
EPK 1230 B2O3 .034
Flint 730
Zinc Oxide 600
Gerstly 330
Dolomite 260
Manganese O2 200
Strontium Carb 160
Tin Oxide 130
Cobalt Oxide 60
Copper Carb 130
Illmenite/granular 130


Pinnells Weathered Bronze =96 Not known to be food safe

Floating Blue Higher in Al2O3 (.666) than limits suggest but ratio of
Si:AL 6.364:1 OK

Bate=92s Clear (crazes on most clays) I was thinking of changing the
Whiting to Wollastonite and maybe adding some Talc while dropping the F4=85.=


Kona F4 3500 .232:1 A:F
Flint 2200 Al2O3 .412
Gerstley 1800 SiO2 3.091
EPK 1000 B2O3 .235
Strontium 800 7.509:1 Si:Al
Whiting 800



Rudy=92s Black (Low on Silica and over the UK limit on Al2O3 =96 a nice blac=
k
matt but is it legit?)

Custer Feldspar 4920 .215:1 Alk:Flx
EPK 1990 Al2O3 .434
Whiting 1790 SiO2 2.217
Zinc Oxide 800 5.114:1 Si:Al
Flint 500

Cobalt Oxide 130
RIO 670

Toby=92s (Randy=92s) Red =96 used by everyone it seems. Pushes the limits o=
n
MgO but seems fine to me

.159:1 A:F
Al2O3 .261
SiO2 3.197
B2O3 .389
12.267:1 Si:Al

We have a Ed's white I think I can easily say is a NO. Si:Al is 3.47:1
Al2O3 =3D .74

Paul=92s white (I see nothing wrong with this glaze but would like it more
white)

Gerstley 157
Talc 86
Whiting 120
Custer 430
EPK 86
Flint 121
Zircopax 81

I won=92t go over the MC6 glazes because those are well documented to be
safe and they are lovely glazes.

Thanks for any input. Donna

William & Susan Schran User on thu 29 mar 07


On 3/29/07 5:51 PM, "Donna Kat" wrote:

> I would like to go to our administrator and say =B3these are our current
> glazes. These are the ones I would not consider good for a
> student/hobbyist environment and these are ones that are good to keep.=B2
> Before doing so I want to make sure what I am saying is correct.
>=20
> Schran=B9s Orange // a good stable glaze I think =AD satin matt creamy orang=
e
>=20
> Dolomite 1750
> Alkalies .178 Fluxes 1
> Spodumene 1750 Al2O3 .321
> Gerstley 800 B2O3 .134
> Talc 350 SiO2 2.624
> F 3134 500
> 8.167:1 Si:Al
> Kona F4 500
> EPK 100
> Flint 2500
>=20
> Spanish RIO 150
> Yellow Ochre 250
> Tine Oxide 350
> Bentonite 150

Thank you assigning my name to your glaze, but you need to know I can't tak=
e
full credit. The glaze is based on an article (can't recall magazine or
author), quite some time ago, that listed two glaze recipes that when
overlapped/combined would result in a look similar to wood firing/shino. I
simply did a line blend of the recipes until I found the "look" I was
seeking. Another article by the same author was published that included my
recipe (the combination of two glazes), but also included suggested
revisions to make it more stable (again, I can't put my finger on the
magazine or author - somebody help me here!).
I found the glaze to be stable when fired properly, but at least do a
vinegar or lemon test to be sure.


--=20
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com

Donna Kat on thu 29 mar 07


>Thank you assigning my name to your glaze, but you need to know I can't
take
>full credit. The glaze is based on an article (can't recall magazine or
>author), quite some time ago, that listed two glaze recipes that when
>overlapped/combined would result in a look similar to wood firing/shino. I
>simply did a line blend of the recipes until I found the "look" I was
>seeking. Another article by the same author was published that included my
>recipe (the combination of two glazes), but also included suggested
>revisions to make it more stable (again, I can't put my finger on the
>magazine or author - somebody help me here!).
>I found the glaze to be stable when fired properly, but at least do a
>vinegar or lemon test to be sure.

Thank you for the information. It is always nice to have a history to a
glaze. I hope you don't mind if we keep your name on the glaze. I
appended Shino to the name when I saw it because it was the closest I have
seen to a real shino. This is when made with Spanish RIO - Special gives a
burnt orange which is also beautiful. While I would like to have the other
recipe I really would hate losing this glaze and I think the studio
population would riot. I will give it a more intense vinegar test. If
this is not a stable glaze then I am really at a loss to understanding what
makes for one. It compares favorably to both MC6 Raspberry and Bone. I
don't suppose you remember what type of changes were made to make it more
stable? Again, thank you for sharing and for sharing.

Donna

Eric Hansen on sat 31 mar 07


Donna: What University program offers only dinnerware?
I'd like to see how they word it in their catalog. And
tableware is only a percentage of "functional"
pottery. Go to Pottery Barn, Walmart, and see if this
isn't true. What on earth is wrong with "decorative"
as a function? - nothing I can think of. There are so
many things made from ceramic besides dinnerware. If
you eliminate all glazes that aren't food safe, then
what about using fritted underglaze in the studio? You
have to eliminate that. Or copper carbonate in the
glaze area? Toxic. Or kilns - too hot and dangerous
around the students. That gas kiln might cause an
explosion. Sounds like an arguement to get rid of the
whole program. A little knowledge is a dangerous thing
- I suggest getting right on board with appropraitely
used liner glazes - and using the language THIS IS NOT
A LINER GLAZE and/or MAKES A GOOD LINER. Toxicology as
a 300-400 level required course makes sence to me. If
a school were considered by OSHA to be a place of
employment you couln't get away with all the stuff you
do. Students deserve to be treated to a knowledgable
approach - when working in a dangerous environment
with potentially harmful substances, rather than be
kept away from it.
"In my humble opinion",
H A M B O N E


--- Donna Kat wrote:

> I would like to go to our administrator and say
> “these are our current
> glazes. These are the ones I would not consider
> good for a
> student/hobbyist environment and these are ones that
> are good to keep.”
> Before doing so I want to make sure what I am saying
> is correct.
>
> Schran’s Orange // a good stable glaze I think –
> satin matt creamy orange
>
> Dolomite 1750
> Alkalies .178 Fluxes 1
> Spodumene 1750 Al2O3 .321
> Gerstley 800 B2O3 .134
> Talc 350 SiO2 2.624
> F 3134 500
> 8.167:1 Si:Al
> Kona F4 500
> EPK 100
> Flint 2500
>
> Spanish RIO 150
> Yellow Ochre 250
> Tine Oxide 350
> Bentonite 150
>
>
> Speckled Blue // questionable – low on silica and
> uses Manganese – I
> would like to eliminate this glaze but I can’t say
> why
>
> Kona F4 3400
> .258:1
> Alkalies:Fluxes
> Neph Sye 1700
> Al2O3 .424
> Whiting 1260
> SiO2 2.115
> EPK 1230
> B2O3 .034
> Flint 730
> Zinc Oxide 600
> Gerstly 330
> Dolomite 260
> Manganese O2 200
> Strontium Carb 160
> Tin Oxide 130
> Cobalt Oxide 60
> Copper Carb 130
> Illmenite/granular 130
>
>
> Pinnells Weathered Bronze – Not known to be food
> safe
>
> Floating Blue Higher in Al2O3 (.666) than limits
> suggest but ratio of
> Si:AL 6.364:1 OK
>
> Bate’s Clear (crazes on most clays) I was thinking
> of changing the
> Whiting to Wollastonite and maybe adding some Talc
> while dropping the F4….
>
> Kona F4 3500
> .232:1 A:F
> Flint 2200 Al2O3
> .412
> Gerstley 1800
> SiO2 3.091
> EPK 1000
> B2O3 .235
> Strontium 800
> 7.509:1 Si:Al
> Whiting 800
>
>
>
> Rudy’s Black (Low on Silica and over the UK limit on
> Al2O3 – a nice black
> matt but is it legit?)
>
> Custer Feldspar 4920 .215:1 Alk:Flx
> EPK 1990 Al2O3 .434
> Whiting 1790 SiO2 2.217
> Zinc Oxide 800 5.114:1 Si:Al
> Flint 500
>
> Cobalt Oxide 130
> RIO 670
>
> Toby’s (Randy’s) Red – used by everyone it seems.
> Pushes the limits on
> MgO but seems fine to me
>
> .159:1 A:F
> Al2O3 .261
> SiO2 3.197
> B2O3 .389
> 12.267:1 Si:Al
>
> We have a Ed's white I think I can easily say is a
> NO. Si:Al is 3.47:1
> Al2O3 = .74
>
> Paul’s white (I see nothing wrong with this glaze
> but would like it more
> white)
>
> Gerstley 157
> Talc 86
> Whiting 120
> Custer 430
> EPK 86
> Flint 121
> Zircopax 81
>
> I won’t go over the MC6 glazes because those are
> well documented to be
> safe and they are lovely glazes.
>
> Thanks for any input. Donna
>
>
______________________________________________________________________________
> 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.
>




____________________________________________________________________________________
Get your own web address.
Have a HUGE year through Yahoo! Small Business.
http://smallbusiness.yahoo.com/domains/?p=BESTDEAL

Ron Roy on sat 31 mar 07


Hi Donna,

The way the glaze is written below - it is not a stable glaze - not enough
silica or alumina - the ratio you have used makes me think the EPK should
be 1000 - not 100 - is that correct?

If so it may be stable but I would say you would need to have it leach
tested to be sure.

RR

>On 3/29/07 5:51 PM, "Donna Kat" wrote:
>
>> I would like to go to our administrator and say "these are our current
>> glazes. These are the ones I would not consider good for a
>> student/hobbyist environment and these are ones that are good to keep."
>> Before doing so I want to make sure what I am saying is correct.
>>
>> Schran's Orange // a good stable glaze I think - satin matt creamy orange
>>
>> Dolomite 1750
>> Alkalies .178 Fluxes 1
>> Spodumene 1750 Al2O3 .321
>> Gerstley 800 B2O3 .134
>> Talc 350 SiO2 2.624
>> F 3134 500
>> 8.167:1 Si:Al
>> Kona F4 500
>> EPK 100
>> Flint 2500
>>
>> Spanish RIO 150
>> Yellow Ochre 250
>> Tine Oxide 350
>> Bentonite 150
>
>Thank you assigning my name to your glaze, but you need to know I can't take
>full credit. The glaze is based on an article (can't recall magazine or
>author), quite some time ago, that listed two glaze recipes that when
>overlapped/combined would result in a look similar to wood firing/shino. I
>simply did a line blend of the recipes until I found the "look" I was
>seeking. Another article by the same author was published that included my
>recipe (the combination of two glazes), but also included suggested
>revisions to make it more stable (again, I can't put my finger on the
>magazine or author - somebody help me here!).
>I found the glaze to be stable when fired properly, but at least do a
>vinegar or lemon test to be sure.
>
>
>--
>William "Bill" Schran

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0