Ron Roy on wed 8 dec 99
Hi Folks - Just my usual warnings about some of these glazes.
>----------------------------Original message----------------------------
>Metallic Black
>Kaolin 95
>Soda Feldspar 1526
>Whiting 106
>Gersley Borate 208
>Copper Carb. 80
>Cobalt Carb. 40
This glaze is high in alkalies and copper - it will probably leach copper
with some foods.
>White Gloss
>Kaolin 270
>Flint 160
>Frit 3134 490
>Tin Oxide 80
This looks OK but the expansion is on the low side - better test it to make
sure it's not a pot buster on your clays.
>Bean Pot Brown
>Frit 3134 200
>Dolomite 200
>Spodumene 200
>Ball Clay 200
>Flitnt 200
>Tin Oxide 50
>Red Iron Oxide 40
Expansion is on the low side - test it for fit on your clays especially if
you are going to use it as a liner glaze.
>Gloss Dark Blue
>Gersley Borate 500
>Kaolin 150
>Flint 350
>Cobalt Carb. 20
John Hesselberth says this is a stable glaze but it has not been tested for
boron release as far as I know - expansion is low - better try some by
itself on the inside of a pot - freeze it overnight and pour in some
boiling water to make sure it won't crack in service.
>Antique Green
>Kaolin 270
>Flint 160
>Frit 3134 490
>Tin Oxide 80
>Copper Carb. 20
>Red Iron Ox. 20
See my comments for White Gloss above.
>Robins Egg
>Flint 56
>Whiting 188
>Soda Feldspar 516
>Kaolin 154
>Zinc Oxide 86
>Copper Carb. 20
>Rutile 40
High zinc glaze - matte (low silica), expansion high so it will craze on
many bodies.
>Dave's Blue
>Kaolin 270
>Flint 160
>Frit 3134 490
>Tin Ox. 80
>Cobalt Carb. 2.5
>Copper Carb. 10
Se my comments above for White Gloss.
>Barium Mat
>Nepheline Syenite 600
>Barium Carbonate 240
>Lithium Carbonate 50
>Kaolin 60
>Flint 50
>Copper Carb. 30
This one will leach barium into certain foods, it will probably craze on
most bodies and may change colour when in contact with certain foods under
soom circumstances.
>Metallic Green
>Ball Clay 60
>Dolomite 180
>Gersley Borate 220
>Spodumene 360
>Tin Oxide 80
>Zircopax 100
>Copper Carb. 60
Way high in copper - it will leach. Expansion on the low side - silica way
low. Probably a matte glaze.
>Moondust
>Soda Feldspar 330
>Wollastonite 300
>Ball Clay 250
>Zinc Oxide 120
>Rutile 50
High zinc low silica - lots of copper - it's gona give up some of that
copper in stuff like orange juice.
>Speckled White
>Gersley Borate 500
>Kaolin 200
>Flint 300
>Zircopax 100
>Rutile 50
Similar to Gloss Dark Blue above but with an even lower expansion.
>Eggshell Blue
>Wollastonite 350
>Soda Feldspar 350
>Ball Clay 390
>Zinc Oxide. 140
>Cobalt Carb. .6
>Rutile 4
Low Silica (probably a matte) high Zinc - expansion is neither very high or low.
>Stonehenge
>Flint 56
>Whiting 188
>Soda Feldspar 516
>Kaolin 154
>Zinc Oxide 86
>Rutile 40
>Ilmenite(add after sieving) 30
>Cobalt Carb. 10
Silica on low side - expansion on high side - will craze on some bodies.
>Mint Mist
>Kaolin 270
>Flint 160
>Frit 3134 490
>Tin Oxide 80
>Copper Carb. 20
See my comments for White Gloss above.
>Blue Brown
>Custer Feldspar 455
>Whiting 236
>Ball Clay 218
>Zinc Oxide 91
>Flint 91
>Cobalt Carb. 20
>Rutile 40
>Red Iron Oxide 20
High Zinc low silica - expansion is high.
>Morgans Tan
>Kaolin 270
>Flint 160
>Frit 3134 480
>Tin Oxide 80
>Red Iron Oxide 30
>Rutile 40
See my comments for White Gloss above.
>Mady's Mat
>Soda Feldspar 500
>Whiting 100
>Kaolin 200
>Zinc Oxide 100
>Talc 150
>Cobalt Carb. 2.5
>Copper Carb. 10
High Zinc - silica on low side - probably a matte glaze - expansion is
neither high or low.
>Asako White
>Flint 56
>Whiting 188
>Soda Feldspar 516
>Kaolin 154
>Zinc Oxide 86
>Rutile 40
>Ilmenite 30
>add Ilmenite after sieving
High zinc, low silica - probably a matte glaze. Expansion is high.
>Jade Green
>Gersley Borate 900
>Flint 585
>Kaolin 315
>Coper Carb. 72
See my comments above for Gloss Dark Blue.
>Bahamas Blue
>Nepheline Syenite 470
>Gersley Borate 270
>Flint 200
>Kaolin 50
>Red Iron Oxide 20
>Cobalt Carb. 15
>Rutile 40
Lots of silica and alumina but alkalies are high (alkalies promote
leaching) - expansion is OK for most bodies. Look for reology problems in
the bucket with all that Neph Sy and GB.
>Floating Blue
>Nepheline Syenite 473
>Gersley Borate 270
>Flint 203
>Kaolin 56
>Red Iron Ox. 20
>Cobalt Carb. 20
>Rutile 40
>Bentonite 11
See above comments for Bahamas Blue - the bentonite is there to help
counteract the reology problems.
I hope some one will get some of these tested at Alfred - let me know if
you need to know what to test for.
RR
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Thonas C. Curran on thu 9 dec 99
Ron, In the foolproof glazes you just posted, the Moondust glaze
mentions copper and warnings about leaching, but copper is not included
in the recipe. You may want to correct.
Carolyn Nygren Curran soon to have new E mail address of
cncpots@capital.net
Gustavo Morcate on thu 9 dec 99
Dear Clayarters;
I don't know the software that RR is using, but surely if you ask me I've
work with this glazes on functional pottery, for a period of two years.
The Art Center were I used them had them for 10 years.
John Hesselberth on thu 9 dec 99
Ron Roy wrote:
>>Gloss Dark Blue
>>Gersley Borate 500
>>Kaolin 150
>>Flint 350
>>Cobalt Carb. 20
>John Hesselberth says this is a stable glaze but it has not been tested for
>boron release as far as I know - expansion is low - better try some by
>itself on the inside of a pot - freeze it overnight and pour in some
>boiling water to make sure it won't crack in service.
This one was tested for boron release with different colorants (1.5%
cobalt carbonate, 3.0% copper carbonate and 1% dark rutile). It was
quite low at 0.196 mg/l.
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"It is time for potters to claim their proper field. Pottery in its pure
form relies neither on sculptural additions nor on pictorial decorations.
but on the counterpoint of form, design, colour, texture and the quality
of the material, all directed to a function." Michael Cardew in "Pioneer
Pottery"
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