Coaster 2mm Fusible Glass Test


In our current stock of glass we have a lot of 2mm Bullseye fusible 90 COE glass. This is fine for some projects, but for others there is the problem of not enough glass volume.

If you are not aware, surface tension tends to try and make glass conform to a thickness of 6mm. For example, if you full fuse a 10mm piece of glass for long enough it will flow out and form a larger piece just 6mm thick. Alternatively, if the piece is less than 6mm it will try to pull in on the sides to reach that 6mm thickness.

So if you start with 3mm clear as a base and then add a 2mm layer, a total of 5mm, a full fuse will probably result in the sides of the piece pulling in. To see if we could make a piece with a 3mm base and a deco layer just 2mm we decided to make some coasters like this as a test.


Ann’s design for the coasters was to be quite simple; clear base with blue, yellow and grey stripes.

To start I cut 4 x 100mm x 100mm pieces of 3mm clear (1101) for the bases.

The 2mm decoration was to be a middle strip of blue, bordered by yellow (1120) and then iridised grey. I set about cutting and trimming all the strips. I did not grind the strips and relied on the cuts being clean enough to butt together.

The coasters were all cleaned and laid up without glue.

They were fired to a full fuse on Bullseye ThinFire shelf paper.

After Firing

Fused Glass Coasters
Fused Glass Coasters

You can see from the photo that the firing didn’t go too well.

The sides did pull in as suspected, but worse, the iridised grey seemed to react with the yellow and did not fuse properly along some edges, leaving a few jagged edges. Where the grey touched the yellow it seemed to pull away leaving clear glass between. The yellow and blue did something similar, but to a much less degree.

The iridised on the edges seemed to not fuse properly to the clear leaving rough edges. I am not sure but maybe iridised glass has some problems with fusing with other colours.

We didn’t have any problem with the shelf paper sticking. All pieces lifted away cleanly and only required minimal cleaning.

Firing Schedule

Full Fuse – 2 layers Bullseye Glass (3mm base and 2mm decoration)

SegmentRate (C/hr)Target (C)Hold (mns)
1. Strain Release54053810
2. ProcessFULL78010
Crash CoolOpen Lid5600
3. AnnealFULL51660
4. Cool1803715

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