The Working End and Forehearth concept developed by BDF is based on the assumption, well proved and generally accepted, that the conditioning of the glass begins just at the furnace exit.
The forming process requires to be fed with glass on a viscosity range that is normally much different from the one we find at the furnace exit.
In the container plants the Working End and the Forehearths must cool the glass, being the exit furnace temperature much higher than what required to grant the necessary glass viscosity for the forming process.
The glass is a material that can not be strongly cooled, therefore the cooling process to be applied must be designed taking into account a number of variables such as the thermal balance, the glass colour, the path, the “head loss”.
We also cannot forget the chemical aspect, as sometimes the glass quality may be affected by the characteristic of the atmosphere which it is in contact with.
The process of glass cooling down taking place after the furnace throat through distributor and forehearths is commonly known as “conditioning”. The conditioning process involves not only the forehearth, but the whole path from the throat to the spout entry.