It is hardly to describe it by words, the best is coming to our factory to check.
For our glass bottles manufactory, we have one big furnace which melt the materials and reach the temperation to 1500°.
We have five lines- automatic and half automatic depending the bottle shape.
One certain weight is for one line but need to reach a certain quantity. If cannot reach , we cannot open the line for such weight.
It is why some bottles we can give customers soon, but some delay a little long time.