Firing Multiple Shelves at Once
In many kilns,
especially deeper ceramic kilns, it's possible to "stack"
several shelves on top of each other, so that multiple shelves
of glass can be fired at the same time. While this
approach can be successful, it does require a knowledge of the
individual kiln and the temperature variation within the kiln.
In most cases, the lower shelf will be
lower in temperature than the upper shelf. It's not uncommon for the temperature
difference between the top shelf of a kiln and the bottom shelf to
be as much as 50 to 75 degrees F (28 to 83C). As a result, items that
are fully fused on the top shelf of a kiln might only tack fuse
on the bottom shelf.
In a multiple
shelf environment it's essential that you experiment to
determine the optimum spacing for what you want to
do. Moving a bottom shelf even a few inches higher
can change the heating characteristics of the kiln.
Similarly, varying the rate of temperature increase also changes
the temperature variation within the kiln, with slower rates
generally leading to more even temperatures throughout the kiln.
here for more
suggestions on how to fuse with multiple shelves.
Copyright 2006 Brad Walker. All rights
Most of these tips came from
posters on the Warm Glass bulletin board.