The paperweights had to dry for about a week until they were bone dry. I sat them on offcuts of plaster board that I changed daily. When they were nearly finished I put them on a wire rack where they could get air right around them to complete their drying.
The paperweights then had a firing to 1000 degrees Celsius (1832 F) in the electric kiln. This temperature gives porous and somewhat fragile pottery that is reasonably easy to glaze and decorate. This firing is known as a bisque firing.
I like to pour my glazes, and for this I use an old milk saucepan that has a pouring lip. With a degree of confidence, and some sleight of hand, it is possible to get quite a nice coating of glaze all the way round a piece of pottery with one continuous pour. Crystalline glazes are generally put on much thicker than a regular glaze, so, holding the paperweights upside down by the glued on ring, I poured two layers without stopping, and also gave the top of each one a quick dip in the glaze bucket. You really need the glaze to be very thick at the top tapering to fairly thin at the lowest point. The glaze will run like mad when it is at high temperature, so you need to allow for that! After 2 or 3 minutes I then applied a little more glaze with a soft brush, and smoothed off any really high spots with a very slightly damp sponge.
The firing was 18 and a half hours from switching on the kiln to switching off. The first 700 degrees (1292 F) was fired slowly overnight whilst the weary potter tried to sleep, leaving the rush to peak temperature for the next morning.
A peak of Cone 10 was reached just before midday, then the temperature was allowed to drop to about 1100 (2012 F), and then held for just over 4 hours to allow time for crystals to grow. I made several adjustments to the growing temperature to try to affect the character of the crystals. Crystals grown at high temperature tend to be spiky, and crystals grown at a lower temperature are much rounder and more like pansy flowers. By varying the growing temperature, it is possible to exploit these different characteristics.
I am happy to report that the glaze firing was a successful one, here is a quick look into the kiln that I opened just 3 hours ago.
Tomorrow I will have the "exciting" and nervous time of separating the paperweights from their porcelain rings. I hope that the alumina did its job!
All going well... more photos will follow of the completed paperweights and I'll share a glaze recipe or two.