Before starting with glassfusing in your kiln you need to do some preparatory work. Most kilns have a brick base, which is not suitable to fuse the glass on because the glass can get stuck on the bricks. You have several options available……

Glass fusing on a kiln shelf: Shelfprimer or ThinFire ?

A good quality kiln shelf is an absolute necessity with glass-fusing. They are available in various sizes. Use a thin kiln shelf when possible, because a kiln shelf absorbs and holds a lot of heat. So if you have a small glass piece to fuse, use a small shelf. A larger kiln shelf is obviously needed for larger glass-fusing objects but larger also means thicker! For very large glass-fusing objects you can use kiln shelfs with open canals inside (Extru shelfs) which control the heat release better.

The glass can not be placed directly on the kiln shelf, since glass can also get stuck on the shelf. Therefore you need to use a glass  release agent.
 This release agent comes in 2 options; Shelfprimer or ThinFire paper ?

1. Shelfprimer. This is a release agent sold as a powder like for instance Primo Primer. You can dilute this shelfprimer powder with water and cover the kiln shelf with 4 or 5 thin layers. Use a very soft brush and leave each layer to dry before adding the next layer. The liquid – purple - shelfprimer sinks in quickly to stir frequently to keep the mixture evenly saturated. Once the shelfprimer has dried completely you can smoothen the shelfprimer on the kiln shelf with your fingers or fine-grained sandpaper. Now you need to place the shelf with the shelfprimer in the kiln and heat it to fixate the shelfprimer on the shelf. After this process the shelfprimer has turned white and is ready for glass-fusing. Depending of the temperature you use for your glass-fusing, the shelfprimer can last from 1 up to 10 firings.

Tip: New mixed shelfprimer powder can be sifted to get rid of any small lumps. 

2. Thinfire kilnfiring paper. This Thinfire paper from Bullseye is a perfect release agent which leaves a very smooth effect on the bottom side of the glass after glassfusing. Using it is very simple; cut a piece of this ThinFire paper, make it a little bit larger than your glass and place it on your kiln shelf, with the Bullseye logo face down. ThinFire paper can be used for one single firing, which makes it more expensive than using a shelfprimer, but the results are always perfect.
   Used Thinfire paper can easily be removed from your kiln (but please wear a dusk protection mask) and your kiln shelf is quickly ready for another glassfusing project!

Glassfusing on ceramic fibre

Ceramic fibre is available in various thicknesses and can be placed directly on the bottom of your glassfusing kiln. You do not need to use a kiln shelf. Since glass has the tendency to stick on the ceramic fibre after glassfusing, it is best to add a thin layer of kiln shelfprimer powder on the fibre. Ceramic fibre has a rough structure, which will be copied on the glass while glassfusing.

New ceramisch-fibre must be “fired out’! Place the ceramic-fibre in the kiln, heat the kiln up to 700°C and hold for 30 minutes. Keep the ventilation holes open at all times to let the gasses out. It is important to have a ventilated area and not to work in the area while this firing takes place, since it will cause quite a nasty smell!. Once the kiln has cooled of it is ready for glassfusing.

The lifetime of ceramic-fibre depends strongly on yourself. All imprints of your fingers or glass pieces will remain as damaged spots in the ceramic-fibre, which will copy themselves in the glass you place there for a next firing. So treat the ceramic-fibre with care and add a new layer of shelfprimer before every new firing to get the best results.

Important: which kiln shelf to use ?

When using a kiln shelf in your glassfusing kiln you need to arrange the best possible heat release. Therefore :1. use a thin kiln shelf as thin as possible,  2. create a space around the kiln shelf with the help of ceramic brackets under the shelf or 3. use a (Extru) kiln shelf with air canals.

1.  in the catalogue you can find details of the available kiln shelfs and ceramic brackets.

2.  Always put ceramic brackets under your kiln shelf, to distribute the heat inside the kiln evenly.

An "Extru" kiln shelf with air canals is the most ideal kiln shelf for bigger glassfusing projects. It is available is large sizes and offers you the possibility to make large glassfusing object without any disturbing lines across the glass.