Once the master lacquer has been cut, it has to be 'processed' into metal 'stampers', that can be put into the pressing machines. Clearly a soft lacquer would be destroyed by the extreme pressure/ temperature in a record press (see Pressing section).
This is achieved by a very delicate and complex process. Firstly, the lacquer is cleaned carefully using a washing system where no physical contact is made with the lacquer, other than with liquids. The lacquer is then 'sensitised', again a liquid 'dip' so as to prepare the lacquer for 'silvering'.
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This is where the lacquer, placed on a slowly rotating vertical turntable, is sprayed with a very fine silver nitrate spray. This penetrates the lacquers grooves with exact accuracy, and prepares the lacquer with a now metal surface, ready for the electro-plating process. |
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This process involves the silvered disc being submerged in a nickel sulphamate electrolyte solution, and being connected to the 'rectifiers' as one of the electric terminals in a plating procedure, which deposits nickel onto the silvered disc. This goes on for one and a half hours or so, after which, thick enough deposits of nickel have been made on the disc to support itself, and it is 'separated' from the original disc. This is called a 'negative', as it is a mirror image of the lacquer. This negative is cleaned, coated with passivator (this stops the coming 'positive' from bonding to it ) and then goes back into the plating baths again, to make a 'positive', by the same electro-plating process previously outlined. This is the positive, and exact, and nickel metal, playable, copy of the master lacquer. After separation from the negative, this again, goes into the plating baths, same process, to make a 'stamper'. This is a direct copy of the negative. Several of these can be made from the positive, as many as needed, depending on the quantity of records required (generally one stamper is good for around 1,000 records, before it splits in the press or is worn out/ discoloured (see Pressing )). After separation, the stamper is trimmed and 'formed', ready to be fixed into the press.