There are many recipes for glass blowing glass. The Jerpoint Glass recipe has thirteen ingredients approximately 50% of which is silica sand. Other ingredients include potash, lime and borax. In the past we mixed all the raw material together ourselves to make our glass for glass blowing, this required a special bunker for the chemicals and a licence from the Gardaì. (Police)
Now our special recipe for glass blowing glass is shipped in 1 tonne crates from a company in Sweden. They mix the recipe and deliver it to us in clear glass nuggets.
At the end of the working day, after we have used up the molten glass in the furnace making our range of handmade glass we need to top the levels back up with the glass nuggets. We also use cullet to top up the furnace. Cullet is waste glass, off cuts and other broken glass that can be re-melted and used again.
We use a scuttle made from stainless steel that delivers about 25kg of our glass nuggets at a time into the melting pot of the furnace. This drops the temperature of the furnace by about 150OC. Often we must repeat this process with another load once the temperature has recovered.
When the pot is full we allow the program to bring the furnace temperature up to 1300OC while melting glass at this high temperature for about 6 hours.
When the glass is melted into something similar to molten lava consistency, the furnace returns to a working Temperature of about 1100OC, ready to be blown into our glassware collections.