hal mc whinnie on tue 10 oct 00
HAL'S METALLIC BLACK
CONE 6
OXIDATION OR REDUCTION
gertsley borate 11
kaolin 4
custer spar 79
whiting 5
cobalt oxide 2
copper carb 4
manganese 4
if glazes in this category contain reasonably stronbg melters they will be
vitreous, their high silica content encourages durability and transparency.
Their normal alumina content discourages glaze flow even if strong melters
are present. this is an excellent category for transparent glazes.
note:
one may wish to add up to 6 % borax to improve on the melters.
HAL'S BROWN GLOSS
silica 18
iron oxide 5
epk 9
custer spar 50
whiting 20
zinc oxide 3
this is an excellent category for a satin or a satin shiny glaze, due to
their high silica content glazes in this category will be quite durable
[ note these glazes were published some years ago in an article of mine in
ceramics monthly. ceramics monthly Feb 1980
John Hesselberth on tue 10 oct 00
hal mc whinnie wrote:
>HAL'S METALLIC BLACK
>CONE 6
>OXIDATION OR REDUCTION
>
>gertsley borate 11
>kaolin 4
>custer spar 79
>whiting 5
>
>cobalt oxide 2
>copper carb 4
>manganese 4
>
>if glazes in this category contain reasonably stronbg melters they will be
>vitreous, their high silica content encourages durability and transparency.
>Their normal alumina content discourages glaze flow even if strong melters
>are present. this is an excellent category for transparent glazes.
Hello Hal and Everyone,
This glaze is virtually identical to one called Metallic Black Glossy
published in Making Pottery without a Wheel by F. Carlton Ball and Janet
Lovoos in 1965.
I have tested it extensively and it is VERY UNSTABLE. Please do not use
it on functional work. Yes, it has plenty of silica but it also has too
much alumina and a very high percentage of its fluxes are sodium and
potassium. It is also loaded up very heavily with colorants. It is also
a glaze that "spits" all over your kiln during firing.
Regards, John
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, perhaps, still necessary to say that the very best glazes cannot
conceal badly shaped pots..." David Green, Pottery Glazes
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