Wade Blocker on mon 1 oct 01
Imzadi,
MG2 white Matt cone 9 to 10 is a great opaque waxy glaze that Carlton
Ball formulated.It is available at Laguna.
Soda spar 41
Kaolin 6
Gerstley borate 12
Dolomite 7
Talc 14
Silica 20
With colorants it is best fired from cone 8 to 9, since it tends to be
runny if thickly applied.It is good in both reduction and oxidation
firing.It is excellent over a slip glaze.
I have used the following additions:
10 % ochre very nice dark brown
5% crocus martis mat medium brown
10% umber lovely mottled brown
10% barnard clay oatmeal color to light brown splotches
1% red Fe,1%rutile, 1% ilmenite - camel colored oatmeal
Here are some more color additions:
green:
0.6 % chrome oxide
0.3% cobalt oxide
1.2% red Fe oxide
This is nice over a coat of plain MG2
blue
0.6% cobalt oxide
0.3 nickel oxide
3.0 rutile
Carlton Ball suggests using Blue Green GS #l00 stain from Pemco Corp
1-2%to get turquoise.
When I fired to cone 9, MG2 was one of my favorite glazes. It is excellent
on porcelain, and just about any clay body I used. Mia in ABQ
Imzadi Donelli on mon 1 oct 01
I ran into a potter who has made a beautiful bright turquoise matte glaze,
cone 10 oxidation, by using Laguna's MG2 commercial glaze and adding both
cobalt (or copper) carb AND chrome to it to achieve the color. He actually
told me the proportions, but I was too bemused, staring at the glaze to
remember or write down the proportions. Ugh! Anyone have any idea what ratio
of these colorants to start experimenting and testing to try to reproduce
this recipe?
A recipe I have for MG2 glaze alone is:
Ball Clay 71.4
Dolomite 99 Feldspar 256.8 (What is this? Will regular Dolomite do? It is
listed
again as an ingredient below.)
Flint 240
Gerstley Borate 113.6
Dolomite 33.2
Talc 186.4
Thanks in advance!
Imzadi
Words scrawled in the ash on one of the storefront windows NOT blown out at
WTC Ground Zero: "They may take our lives, but they will never take our
freedom!"
Donald Goldsobel on thu 4 oct 01
A simplified MG2 formula I found in an old Carlton Ball publication is
below. I have used it and it works just like the Laguna commercial glaze. If
you figure out the proportions for the oxides, let us all know. There is a
copper matt I use called John's Dry which is higgh in barrium an uses 3%
copper carbonate.. the formula is below
MG2 Cone 10
SODA SPAR 12.84
BALL CLAY 3.57
GERSTLEY BORATE 5.68
DOLOMITE 4.16
TALC 9.32
SILICA 12.00
John's Dry cone ten best over light body and start using it thinly.
EPK 8
Barium 16
Neph Si 6
Copper CARB 3%
.>
> Good luck,
Donald Goldsobel-who just returned from the Grand Canyon and Sedona and
found 700+ messages to sift.
>
.>
____________________________________________________________________________
__
> 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.
Wade Blocker on sat 6 oct 01
Ron,
I am using several bowls with the MG2 matt glaze on them. I made those
bowls over 30 years ago, and they look brand new still. They have ben used
in the microwave and are washed in the dishwasher. What more can one ask
for? Mia in ABQ
Ron Roy on sat 6 oct 01
Just in case anyone is planning to use either of these on food bearing
surfaces -
The first one is probably not stable and the second one is going to change
colour if you look at it sideways - try a slice of orange or lemon on it
over night - well for an hour anyway.
With over 50% barium carb it will release barium into food easily. High
expansion means it will craze as well.
RR
>A simplified MG2 formula I found in an old Carlton Ball publication is
>below. I have used it and it works just like the Laguna commercial glaze. If
>you figure out the proportions for the oxides, let us all know. There is a
>copper matt I use called John's Dry which is higgh in barrium an uses 3%
>copper carbonate.. the formula is below
>MG2 Cone 10
>SODA SPAR 12.84
>BALL CLAY 3.57
>GERSTLEY BORATE 5.68
>DOLOMITE 4.16
>TALC 9.32
>SILICA 12.00
>
>
>John's Dry cone ten best over light body and start using it thinly.
>EPK 8
>Barium 16
>Neph Si 6
>Copper CARB 3%
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
David Hewitt on sun 7 oct 01
In message , Donald Goldsobel writes
>A simplified MG2 formula I found in an old Carlton Ball publication is
>below. I have used it and it works just like the Laguna commercial glaze. If
>you figure out the proportions for the oxides, let us all know.
>MG2 Cone 10
>SODA SPAR 12.84
>BALL CLAY 3.57
>GERSTLEY BORATE 5.68
>DOLOMITE 4.16
>TALC 9.32
>SILICA 12.00
Total 47.57
I presume that this is correct
>
>
>
>Donald Goldsobel-who just returned from the Grand Canyon and Sedona and
>found 700+ messages to sift.
If it is of interest I have analysed this recipe and come up with the
following:-
K2O .028 Al2O3 .209 SiO2 2.953
Na2O .113 B2O3 .131 TiO2 .005
CaO .284 Fe2O3 .003
MgO .575
For the Ball clay I have taken Hyplas 71. THE GB is a May 1999 analysis.
The other materials are as I get in the UK. The calculation has been
made using my "Glaze Workbook" program.
Expansion is E&T 3.19 x 10-6/oC, which is low and hence crazing is
unlikely.
The glaze is high in alkaline earths and I wonder what it would look
like without the GB. I wouldn't normally expect to see a boron
containing RM used in a cone 10 recipe.
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Joan & Tom Woodward on mon 8 oct 01
I wonder if it's true that just because of CA laws the glazes are safe. I
did the old 3-day lemon slice test on a Laguna glaze on 2 different clays
and came up with blue rind on both. Very disappointing. I do intend to
test again, but meanwhile have not been using the glaze on food surfaces.
Joan, a little farther north in Colorado.
Original Message -----
From: Wade Blocker
To:
Sent: Monday, October 08, 2001 11:38 AM
Subject: Re: MG2/Turquoise matte glaze oxide ratio needed
> Roy,
> MG 2 Matte is really not that mat a glaze inspite of the name. It is
not
> shiny, unless it has added oxides which make it more glossy. I have no
> cutlery marks on it.
> Roy, I am not a production potter and therefore am most interested in
how
> a glaze looks. .That is not to say that I use obviously unsafe glazes. I
> have tried glazes submitted to Clayart as written originally and after
> they have been altered to be " food safe.". The original recipes are
more
> appealing to me than the altered glazes.Some of the alterations rob the
> glaze of its uniqueness.
> Carleton Balls' glazes, ( I have dozens of them from CM when Professor
> Ball had a monthly column)are generally very dependable glazes. Westwood
> Ceramics, later Laguna, sells some of his glazes. Particularly Transparent
> 16, MG 2 Matt, G Matt 3.just to mention a few. The last glaze. can
result
> in some wonderful effects.The State of California has very stringent laws
> about glaze safety. If there was a question about them they would not be
> sold nor used by many potters.
> There was a letter to Clayart within the last few days,from someone who
> analyzed MG2 and said that it would not craze, and was therefore durable.
> Mia in sunny ABQ where balloons dot the sky like jewels in the morning.
>
>
____________________________________________________________________________
__
> 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.
>
Wade Blocker on mon 8 oct 01
Hello Craig,
My missive was in response to RR's letter in which he said that MG2 was
likely to craze. Mia
Ron Roy on mon 8 oct 01
My remarks on this glaze are based on what John and I have learned from his
work on glaze stability. There are several problems with it. It is short of
both alumina and silica and the fluxes are dominated by an oversupply of
MgO.
It is matte because the excess MgO is crystallizing on the surface of the
glaze during cooling. This would make it susceptible to acid attack on the
surface. This in itself is not a problem with the glaze the way it is -
however it is possible that some potters will try adding colouring oxides
to it and that is where the fun will start.
The expansion is also quite low and that may be a problem when it is on
certain clays - especially those with iron in them and/or those bodies
which develop cristobalite.
It would be very difficult to tell how durable this glaze by looking at it
because it is matte - one of the standard tests for durability is the 24
hour vinegar immersion. The way you can tell if the acid is able to attack
the glaze is loss of shine. With a matte glaze you would not be able to see
the deterioration.
There are those on this list who do want to know which glazes are durable
and which are not - if you are looking for a durable glaze for the inside
of functional work you can do a lot better than this one.
The microwave and dishwasher aspects are usually a separate issue and have
to do with whether the clay is well enough vitrified to exclude water.
Perhaps you can tell us if it marks with cutlery - most matte glazes do and
that would be another reason to not use it inside vessels.
RR
> I am using several bowls with the MG2 matt glaze on them. I made those
>bowls over 30 years ago, and they look brand new still. They have ben used
>in the microwave and are washed in the dishwasher. What more can one ask
>for? Mia in ABQ
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Wade Blocker on mon 8 oct 01
Roy,
MG 2 Matte is really not that mat a glaze inspite of the name. It is not
shiny, unless it has added oxides which make it more glossy. I have no
cutlery marks on it.
Roy, I am not a production potter and therefore am most interested in how
a glaze looks. .That is not to say that I use obviously unsafe glazes. I
have tried glazes submitted to Clayart as written originally and after
they have been altered to be " food safe.". The original recipes are more
appealing to me than the altered glazes.Some of the alterations rob the
glaze of its uniqueness.
Carleton Balls' glazes, ( I have dozens of them from CM when Professor
Ball had a monthly column)are generally very dependable glazes. Westwood
Ceramics, later Laguna, sells some of his glazes. Particularly Transparent
16, MG 2 Matt, G Matt 3.just to mention a few. The last glaze. can result
in some wonderful effects.The State of California has very stringent laws
about glaze safety. If there was a question about them they would not be
sold nor used by many potters.
There was a letter to Clayart within the last few days,from someone who
analyzed MG2 and said that it would not craze, and was therefore durable.
Mia in sunny ABQ where balloons dot the sky like jewels in the morning.
Craig Martell on mon 8 oct 01
Mia sezed:
>There was a letter to Clayart within the last few days,from someone who
>analyzed MG2 and said that it would not craze, and was therefore durable.
Hello Mia:
The above statement is a misconception about durability. Lack of crazing
does not make a glaze durable. Durability is a function of the total glaze
composition and in particular the molecular levels of alumina and silica
against the fluxes, colorants, and opacifiers. It has been stated ad
nauseum via Clayart that durability can only be suggested in terms of
probability when looking at the molecular formula of any glaze. Only leach
testing by an accredited laboratory can give one quantitative answers to
durability.
regards, Craig Martell in Oregon
Earl Brunner on tue 9 oct 01
Mg2 may be "safe" by itself, even if it leaches (i.e. no toxic
materials). Have you ever read the disclaimers on stuff like glazes?
They will not claim that it will be safe in all firing conditions or
with any additives (colorants). How could they? They have no control
over whether you over or underfire, or reduce the firing.
If I remember right MG2 is a white glaze, if YOU add colorants to it or
oxide decoration, YOU become responsible. Leaching does not mean you
are going to die if the stuff that leaches doesn't poison you.
Joan & Tom Woodward wrote:
> I wonder if it's true that just because of CA laws the glazes are safe. I
> did the old 3-day lemon slice test on a Laguna glaze on 2 different clays
> and came up with blue rind on both. Very disappointing. I do intend to
> test again, but meanwhile have not been using the glaze on food surfaces.
> Joan, a little farther north in Colorado.
>
> Original Message -----
> From: Wade Blocker
> To:
> Sent: Monday, October 08, 2001 11:38 AM
> Subject: Re: MG2/Turquoise matte glaze oxide ratio needed
>
>
>
>> Roy,
>> MG 2 Matte is really not that mat a glaze inspite of the name. It is
>
> not
>
>> shiny, unless it has added oxides which make it more glossy. I have no
>> cutlery marks on it.
>> Roy, I am not a production potter and therefore am most interested in
>
> how
>
>> a glaze looks. .That is not to say that I use obviously unsafe glazes. I
>> have tried glazes submitted to Clayart as written originally and after
>> they have been altered to be " food safe.". The original recipes are
>
> more
>
>> appealing to me than the altered glazes.Some of the alterations rob the
>> glaze of its uniqueness.
>> Carleton Balls' glazes, ( I have dozens of them from CM when Professor
>> Ball had a monthly column)are generally very dependable glazes. Westwood
>> Ceramics, later Laguna, sells some of his glazes. Particularly Transparent
>> 16, MG 2 Matt, G Matt 3.just to mention a few. The last glaze. can
>
> result
>
>> in some wonderful effects.The State of California has very stringent laws
>> about glaze safety. If there was a question about them they would not be
>> sold nor used by many potters.
>> There was a letter to Clayart within the last few days,from someone who
>> analyzed MG2 and said that it would not craze, and was therefore durable.
>> Mia in sunny ABQ where balloons dot the sky like jewels in the morning.
>>
>>
>
> ____________________________________________________________________________
> __
>
>> 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.
>
>
> ______________________________________________________________________________
> 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.
--
Earl Brunner
http://coyote.accessnv.com/bruec/
bruec@anv.net
Ron Roy on fri 12 oct 01
Hi Mia,
It is up to you to use whatever glazes you want to - none of my business -
I just think - when I have information which might be useful to potters -
and it is not included with the recipe - I should pass that information on.
There are many production potters on this list - it is hard enough to make
a living in pottery without having glazes backfire on us. What we want is
for our customers to come back and buy from us again. If glazes change
colour in use I would expect those customers to stay away.
I did not say that glaze would craze. That information was about the 2nd
glaze - the one with all the Barium in it - that will change colour in use.
In fact my second post included a warning about the low expansion of the
MG2 and that it could shiver on some high contraction bodies.
Durability has little to do with crazing - only - if a glaze is crazed -
and acid contact results in leaching - the acid has more surface to work
on. It is still the glazes resistance to acid attack (food) that is the
main criteria for durability.
When John and I get our book published you are going to see just how
interesting some stable glazes are. Just because a glaze is stable does not
mean it has to be uninteresting - Up until now I don't know of anyone who
was trying to do both - perhaps that is a comment on the general attitude
of glaze makers from the past.
It would be very easy to find out which of Mr. Balls glazed were stable -
all I need are the recipes.
Exactly what do the laws in California cover?
RR
> MG 2 Matte is really not that mat a glaze inspite of the name. It is not
>shiny, unless it has added oxides which make it more glossy. I have no
>cutlery marks on it.
> Roy, I am not a production potter and therefore am most interested in how
>a glaze looks. .That is not to say that I use obviously unsafe glazes. I
>have tried glazes submitted to Clayart as written originally and after
>they have been altered to be " food safe.". The original recipes are more
>appealing to me than the altered glazes.Some of the alterations rob the
>glaze of its uniqueness.
> Carleton Balls' glazes, ( I have dozens of them from CM when Professor
>Ball had a monthly column)are generally very dependable glazes. Westwood
>Ceramics, later Laguna, sells some of his glazes. Particularly Transparent
>16, MG 2 Matt, G Matt 3.just to mention a few. The last glaze. can result
>in some wonderful effects.The State of California has very stringent laws
>about glaze safety. If there was a question about them they would not be
>sold nor used by many potters.
> There was a letter to Clayart within the last few days,from someone who
>analyzed MG2 and said that it would not craze, and was therefore durable.
>Mia in sunny ABQ where balloons dot the sky like jewels in the morning.
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
| |
|
