It was in 1876 that it was decided to replace the ‘Chalon Head’ stamps. The design had been in use since 1860 and with the exception of the Fourpence which was lithographed all had been printed from the steel plates engraved by Perkins, Bacon Ltd in London. The new stamps were to be surface printed and after Mr Knight, the head of the Lithographic Branch with the title of Engraver and Lithographer, had visited Sydney and Melbourne for advice it was decided to print them from locally made plates. William Bell of Sydney was asked to engrave a master die on steel but this did not materialise until May 1877.
Reproduction from the master die was done by the then new process of electrolytic deposition. In its very simplest form, the procedure was as follows. The master die was positioned on an appropriately sized flat slab of lead and then pressure was applied so that an impression of the design was transferred to the lead (Figure 1).
It is necessary to appreciate that the only source of electricity was a primary battery and the apparatus at Mr Knight’s disposal could not have been much more sophisticated than that shown in this drawing from an 1890 textbook (Figure 3).
The copper layer or shell was carefully separated from the mould and backed up with type metal. This then was an electrotype of the master die and because the copper deposition had been of molecular fineness the detail of the design was precisely copied (Figure 4).
The white areas on the master quadruple electrotype were recessed and would be in relief on the lead mould. The design was intricate in places and it was not difficult for some minor damage to be done during the polishing operation. The damage was in fact minimal but what there was faithfully reproduced on the copper shell. When the shell was removed from the mould it is also likely that the engraver did a little cleaning up with his graver. The overall alterations from the original design were very small but they were sufficient to make each unit of the quartet slightly different from its neighbour and these differences were reproduced on every electrotype made from the master.
Rather surprisingly, the other denominations were derived from One Penny quadruple electrotypes rather than by the production of an individual secondary master die for each. These were most probably prepared by cutting away the unwanted words of value from a lead mould on all four subjects of an electrotype leaving blank spaces in the positions previously occupied by the words ONE PENNY. The words of the new denomination were then engraved by hand on each subject in turn to produce the master quadruple electrotype. Because the new wording was done by hand there are differences in the lettering from one stamp to the next, this provides an additional aid, and on some denominations, a more easy method of identifying the position of a stamp within its quartet. The Twopence was the first other denomination to be produced and this utilised the Die I One Penny electrotype. All the other denominations and a later replacement for the Twopence (the catalogued Die II stamps), were derived from the Die II One Penny electrotype. This is shown diagrammatically in Figure 11.