The production of zinc needed many different procedures.
In Oberhausen the zinc ore was crushed
and roasted at a temperature of 800 degrees.
During the process the sulphur it contained escaped into the surrounding air.
After roasting was completed, the material was taken
to be smelted at the zinc plant in Borbeck.
Zinc ore and coal were shovelled into fireproof clay tubes,
the so-called 'muffles'.
These were heated in reduction furnaces.
The resulting zinc vapour
condensed on the protruding parts of the tubes
where it could be skimmed off.
Working with zinc was hard and dangerous.
Heating the raw material produced toxic fumes
containing lead, cadmium and arsenic.
Zinc pullers could be identified by their so-called 'lead seam',
a black line of lead poisoning
deposited on the edge of their gums.
A chronic cough known as 'smelters puke',
was a daily occurrence, as were many other diseases.
The resulting crude zinc was transported back to Oberhausen
where it was re-smelted to pure zinc in a gas-fired furnace.
Through an opening at the side, the molten zinc was filled
with a large ladle into a mould in the casting carousel.
The lead settled at the bottom of the gas-heated furnace.
The layer of slag which formed on the surface had to be removed.
The cooled zinc was chipped out of the mould with a chisel
and cut with mechanical scissors.
The zinc ingots were then rolled into sheet metal in several steps.
The workers had to move the heavy sheets
in the roller with their hands or tongs.
The workers used gloves to protect their hands,
but sharp-edged sheets often cut the leather and scored their hands.
The calluses on their hands provided better protection.
The finished sheets were cut to size.
They were used for things like making gutters, drainage pipes
or as sheet metal for offset printing.