Tom Buck on sat 14 aug 99
Cheryl:
The standard densities for glaze slurries are scattered here
and there throughout the litertaure. eg, Cardew gives one bit of info,
Rhodes another, Zakin, et al, all make mentions.
I routinely do density determinations when the glaze has sat
around for awhile, then I also do the "finger" check first (taught by
teacher Darlene Benner of Mohawk College). If the glaze stays in the
creases but barely coats the rest of the finger then it is very close to
being ok for dipping C06 biscuit (count of 3 to 5).
Within reason (there are exceptions):
Spraying density: 1.42-1.47 grams/mL (200 mL weighs 285-295 grams)
Dipping density: 1.53-1.58 g/mL (305-315 for 200 mL)
Brushing density: 1.65-1.67 g/mL (330-335)
Now, since most pots are bisqued to either 1000 oC (Cone 06 Orton large)
or to 1060 oC (Cone 04 Orton large), it can be assumed the porosity
(absorption) will be 6% (C04) to 9% (C06). Hence the "hard" biscuit will
need a few seconds longer residence in a dipping glaze. For spraying or
brushing, the potter themself will decide when the glaze coat is thick
enough, although it is common practice to brush on three coats, each at a
different angle.
For rakuware, many potters prefer to bisque to 900 oC (C010 or
lower), so that there will be more takeup of wash or glaze, and hence
enhanced texturing effects.
Does this answer your query?
BFN.
Tom Buck ) tel: 905-389-2339 (westend Lake
Ontario, province of Ontario, Canada). mailing address: 373 East 43rd
Street,
Hamilton ON L8T 3E1 Canada
| |
|
