Pottery In Australia Vol 36 No 2 Winter 1997

GREAT
GLAZES
Opaque White Glaze
CHRIS MYERS, Senior Lecturer, Peninsula School of Art, Monash University.
is an oxidised high fIre
alumina than the soda felspar.
glaze thar I have found to be
It will also take colourants
-n'is
very reliable and one that I
quite readily and is worth
have used CO!1SIal1t1y for over twenty
experimenting with to obtain
year.;. I think thar it was fir.;( shared
good quality coloured glazes.
by Mitsuo Shoji when he anived in
The glaze is unsuitable for
Australia from Japan in 1973. As a
underglaze or engobe decoration
result I call it Mitsuo's Whire.
as it's opacity will cover any
This glaze is a very smooth,
colour, but it will accomodare
opaque satin white and is 'Shallow Dish'. Multiple sandblastings. sprayed colour blushes and brush
suitable for domestic wares as w60cms. strokes with a good hard edge
well as for sculptural pieces. I use it on large sculptures can be obtained on this surface.
where I lVant to emphasise shadow and negative space, I find that this is an excellent glaze for post firing
but it is equally effctive on functional work as it doesn't decoration. It sandblasts be-dutifully and higlliights lustres
mark and is easily cleaned. extremely weU. Mother of Pearl lustre gives this glaze a
beautiful opalescent quality. TIle even whiteness of this
RECIPE
1l1e lUlity
glaze also provides an excellent canvas for decorating with
Soda Feldspar 55.7 molecular
on·gIaze enamels.
Kaolin 83 fonnula is
To gain the purest white, a white porcelaineous clay is
Whiting 13.3 K20 0.082 really required. I use Clayworks TMK which under
Talc 12.7 Al203 0.396 oxidation provides this. Iron bearing clays are also
Tin Oxide 10.0 Si02 2.311 attractive under dlis glaze. Edges anJ textures will break to
a20 0.179 a light rusty hue, particularly if the glaze is thinly applied.
Sn02 0.191 I spray the glaze fairly thickly so that the sandblasting will
eaO 0.476 produce texture, but even then I still find the glaze flow to
Fire to cone 10. MgO 0.263 be very stable. Rarely does it run and 1 always flatten Cone
10 completely. Naturally if it is not tired to a full cone 10
Some interesting combinations are:
the glaze surface will become increasingly matt and when
0.25 cobalt carbonate - a gende pale blue
reduuion fIred it loses its whiteness and becomes clear.
0.5 cobalt carbonate plus 1.0 nickel - a blue/white Mitsuo's white has been used by students of Monash
1.0 nickel plus 3 copper oxide - a golden brown University since the days of the Caufield Institute. It is a
good sta ndard all purpose glaze and one of my
favourites. Thank you Mitsuo. 00
I have found that if a direct exchange is made with
potash felspar instead of soda, that the glaze will fire
slightly glOSSier and dle white intensifies. This is because
the potash felspar contains slightly more silica and less
Chris Myers, POller/ Academic
Senior Lecturer, Peninsula School of An, Monash University.
52 POTIERY IN AUSTRAUA + ISSUE 31/2 WlNTER 1997