How to use
This material is made out of alumina and silica (the core components of clay) fibres pressed together with an organic binder (similar to the glue we use in enamelling). Handle the fibre with care to avoid unnecessary creation of dust and damage to the edges of the fibre. These materials are inert, but heavy long term exposure to them can be damaging to the lungs (this is a problem in industrial settings), and minimising dust creation in the workshop is always best practice. The fibres can also be irritating to the skin.
The fibre can be cut to size with a craft knife. Wear a respirator. Cutting in several gentle passes will generate less dust. After cutting, wipe down all work surfaces with a damp cloth to collect this dust without making it airborne. Immediately proceeding to firing the fibre and kiln washing it (see below) will stop further production of dust. If the fibre is not to be processed at this time, keep it in its closed plastic bag.
Firing of the binder
Before the first use, the fibre must be fired to eliminate the binder. The fibre will turn black and produce a non-toxic smoke and odour. Ventilate the workshop while this operation is carried out. This only needs to be done once. Allow the fibre to sit in the hot kiln, the temperature can be set between 800 and 900 degrees celsius (1470-1650 F), until the fibre returns to white. Opening the door before the binder is consumed will allow oxygen in, which will create a flame, and more smoke. This is not a problem, just close the door again and the oxygen within the kiln will be consumed.
The duration of this firing will depend upon the size of the fibre, temperature of the kiln, if more than one fibre is fired at once, etc. As a guide, the fibre is likely ready after 15 minutes firing.
Once the binder is burnt off, the fibre is ready for indefinite use and will not give off smoke anymore.
Kiln washing the fibre
We strongly recommend that the fibre is entirely covered in kiln wash or kaolin after the binder has been burnt off.Mix the kiln wash with water until a creamy consistency is achieved, and apply with a flat brush to all surfaces and edges of the fibre, you will need to apply on one side and let dry; then turn and apply to the other side.
This has several advantages, not least of which, it stops the shedding of the tiny fibres that make up the material during handling.
Kiln wash also makes it much easier to deal with enamel spills, which can be scraped off, and the kiln wash renewed; this greatly extends the working life of the fibre.
During firing, the counter enamel on a domed piece might sometimes flow excessively and touch the firing support. A very fine layer of kiln wash will then stick to enamel; if the enamel is allowed to cool for a few seconds before prying it off the firing support, it will break apart with very little force from the kiln spatula. The kiln wash residue comes off the enamel when scrubbing under water with a glass brush.