Well now. Lots of thanks to Holly Flannaghan, my technician comrade in Geography who has access to a furnace, and also does her research!
This is Alice la Porta’s mould painted with the Aluminium Kiln Wash to stop the glass adhering to the mould. It did more or less work. The mould was unfired and next time we may use an already fired ceramic mould.
I had three grades of glass cullet. Sand, sub-1cm, and above 1cm. We used the sand and sub-1cm cullet on the top to fill up the mould.
Then Holly performed her magic. Over four hours the temperature was gradually raised to around 1000 degrees Centigrade, and then kept there for two hours or so before starting the slow cooling process.
And one day later here we are. The Aluminium Kiln Wash worked but we had to break up the mould to get access to the glass. Once out the glass was actually thinner than I anticipated. The sub-1cm cullet must have had a lot of gaps that it had to fill. Next time we will use the sand only and a slightly higher mould to give the slab more depth.
The glass appeared not ideal. It looked similar to the fused glass blocks produced using Nacho’s kiln. However, once I started to work it I realised that it actually had very good internal cohesion. It flaked well although crumbly.
And this is it. The outcome but also a starting point. We need to adjust the mould size and make sure it’s already fired. Use sand rather than sub-1cm cullet and perhaps keep it at 1000 degrees Centigrade for around four hours before allowing a very slow cool off period.
I am actually super happy with this handaxe. Many thanks Holly!