After the mixing of the compound and the calendering, that is the
spreading it in sheets, the great roll of rubber and cloth that is to
be made into corrugated matting is sent to the pressman. Here it is
hung in a rack and fifteen or twenty feet of it drawn between the
plates of the huge hydraulic steam press. The bottom plate of this
press is grooved its whole length, so that when the upper platen is
let down the plain sheet of rubber is forced into the grooves and the
corrugations are formed. While in that position steam is let into the
upper and lower platens and the matting is cured. After it has been in
there the proper time, cold water is let into the press, it is cooled
off, and the upper platen being raised, it is ready to come out. A
simple device for loosening the matting from the grooves into which it
has been forced is a long steel rod, with a handle on one hand like an
auger handle, which, being introduced under the edge and twisted,
allows the air to enter with it and releases it from the mould.