Dana, many thanks for your
many thanks for your reply. I’ve now tried this mould three times, reducing the upper temperature and increasing the hold time (1st time – 733°C & 15 mins; 2nd time – 680°C & 15 mins; 3rd time – 700°C & 20 mins). The third one was the most successful but there was still a certain amount of “dog boning” (describes it perfectly!).
I think the next one I’ll use slightly oversize glass and two layers. What do you advise with regard to upper temperature and hold time? I endeavour to change a single variable each time but fear it would take me forever to reach a sensible conclusion!