Tender’s whistles are lost wax cast in England in two pieces, from solid brass. They are fitted onto a brass-plated steel keyring and are modeled on a British Railway guard’s ‘pealess’ whistle from the early 20th Century.
To produce this whistle, first Tender’s jeweler made a quick test run in wood, to check the design worked in theory. Then he created the master with hand tools, using copper and iron. This needs to be in two parts, the shaft and front of the whistle, and the button back section. This is so that a space can be sealed inside to allow the air to return on itself and sound a note. These master sections are then used to make a mould, into which wax is poured. The waxes of each section are packed in plaster, and molten brass is run in, melting away the wax and hardening inside the plaster. The plaster is then broken away and the pieces are filed and cleaned up.
The final joining of the two sections is done by the jeweler who made the original model. This is done with silver solder, which seals any gaps in the joint, and runs over slightly down the sides of the whistle. Any excess is removed, but the traces of silver and heat leave inconsistencies in the colour and patina of the whistle, which make every piece unique.
The coppered whistle will tarnish from a bright red copper to a soft green verdigris, eventually wearing away to show the brass below.