Judith Enright on wed 9 dec 98
Thanks for the Emerald Green glaze (from Larry Phillips, I believe) posted
recently. The recipe was given in grams and I converted it to percentages.
Herewith, the conversion:
Neph Sye 46.9
Talc 33.8
Whiting 20.0
Colemantite 13.1
EPK 10.0
Zinc Oxide 1.3
TOTAL: 125.0
Add:
Copper Carb 6.25
Given that the base ingredients exceed 100%, would Ron Roy or Tom Buck or
other of our glaze experts care to discourse about whether this glaze is
durable and food-safe?
Thanks!
Judith Enright
Lori Pierce on thu 10 dec 98
Judith Enright...I missed the original Emerald Green glaze recipe. What
cone, please. What atmosphere...oxidation or reduction? Thanks, Lori Pierce
-----Original Message-----
From: Judith Enright
To: CLAYART@LSV.UKY.EDU
Date: Wednesday, December 09, 1998 1:01 PM
Subject: Emerald Green - Conversion to Percentages
----------------------------Original message----------------------------
Thanks for the Emerald Green glaze (from Larry Phillips, I believe) posted
recently. The recipe was given in grams and I converted it to percentages.
Herewith, the conversion:
Neph Sye 46.9
Talc 33.8
Whiting 20.0
Colemantite 13.1
EPK 10.0
Zinc Oxide 1.3
TOTAL: 125.0
Add:
Copper Carb 6.25
Given that the base ingredients exceed 100%, would Ron Roy or Tom Buck or
other of our glaze experts care to discourse about whether this glaze is
durable and food-safe?
Thanks!
Judith Enright
Ron Roy on sat 12 dec 98
Hi Judith - it's not in percent yet but if the numbers are correct it's way
short of silica with B2O3 out of unity for a cone 6 glaze - even worse if
I look at it with limits designed to include Boron in unity - and as John
points out - thats a lot of copper to start with. So I would bet it's not
durable and might even change colour when in contact with certain foods
long enough.
Food safe has many aspects and I don't know enough about the toxicity of
copper to say what the effect would be of say drinking 5 cups of tea a day
out of a mug glazed with this - I do know I would not want to - nor would I
feel right in telling anyone else to.
>----------------------------Original message----------------------------
>Thanks for the Emerald Green glaze (from Larry Phillips, I believe) posted
>recently. The recipe was given in grams and I converted it to percentages.
>Herewith, the conversion:
>
>Neph Sye 46.9
>Talc 33.8
>Whiting 20.0
>Colemantite 13.1
>EPK 10.0
>Zinc Oxide 1.3
>
>TOTAL: 125.0
>
>Add:
>
>Copper Carb 6.25
>
>Given that the base ingredients exceed 100%, would Ron Roy or Tom Buck or
>other of our glaze experts care to discourse about whether this glaze is
>durable and food-safe?
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
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