8. Four day tanks

This was a highly simplified oven designed for manual picking. It was designed to compete with the pot-oven and to avoid the constraints of pot manufacture and preheating. It consists of a simple tank and a superstructure housing one or more burners, generally operated by cold air (no heat recovery system).

The operating cycle is similar to that of a pot furnace:

• some 60-75% of the glass in the tank is removed during working periods of up to 8 hours;

• The tank is then refilled with composition, and the melting, refining and cooling cycle at working temperature takes place over the next 16 hours.

The success of this type of furnace has been very limited, as it is difficult to obtain good quality glass, and there is the problem of the refractories in...