The description
The objective is a sculpture 50mm x 50mm x 90mm (2” x 2” x 3.5”) composed of two layer slabs to make it 90mm high. The objective is to fuse the whole without distortion or dams.
Assumption:
My presumption is that the piece will be fired on its side rather than standing to full height in the kiln.
Proposition:
I propose that a sharp tack or sinter firing can achieve this project. Sintering is the use of a low temperature for a long time to achieve a result that a normally high temperature and short soak would achieve, but without the distortion from the crisp square edges wanted for this sculpture. It can stick pieces together with virtually no change in appearance.
Scheduling:
This is a piece of 50mm (2”) at its thinnest, so a slow first ramp rate is necessary. I suggest heating up as for 50mm will be slow enough to avoid breaks. The heat up could be;
22°C (40°F) - 260°C (500°F), 60’,
22°C (40°F) - 670°C (1238°F), 8 hrs,
Sharp tack/sintering requires annealing as for 2.5 times the thickest part, making a requirement to anneal as for 125mm/5”, which would be for 20 hours. The associated cool would be:
cool to 427°C (800°F) at 1.2°C/hr (2°F/hr)
cool to 371°C (700°F) at 2.2°C/hr (4°F/hr)
cool to 21°C (70°F) at 3.05°C/hr (5.5°F/hr)
off.
Because the rates are so slow it may be best to set the controller to use the time to reach the target temperature.
13.36 hours to 260°C (500°F), 60’
1hr to 301°C (574°F)
16.81 hours to 670°C (1238°F)
8 hrs to 671° (1240°F)
0 hrs to anneal temperature
20 hours to anneal temperature +1°
45.83 hours to 427°C (800°F)
25.45 hours to 371°C (700°F)
100 hours to to 21°C (70°F)
or 230 hrs minimum anneal and cool time (or 9.6 days). Casting might be quicker in the long run.
