Tender’s glass objects are mouth blown in England from lead free glass.
Rather than being cast or mechanically mould blown, as most glassware is today, these pieces are free-blown in the manner that glass has been worked since the First Century BC. During the blowing process, the rod on which the tumbler is made leaves a ‘belly button’ or punty mark on the base.The punty mark is sometimes ground away, to leave a perfectly smooth bottom, but to show its construction story,Tender’s tumblers have the punty mark still showing.
The final stage of production is to press one of Tender’s lost wax-cast solid brass jeans buttons, showing Plautus’ face, into the soft glass base. Then the tumblers must be carefully placed in an annealing oven, which cools them down very slowly, over twenty-four hours, so that the glass does not crack.