Record electroplating is one of the oldest applications of electroforming and has essentially remained unchanged since the 1920s. Record production begins with a cut on a foil, from which prints are made by electroplating, which are then used as press dies. These are divided into lacquer and DMM cuts.
In classic lacquer cutting, the grooves are cut into an aluminum blank coated with acetate foil (father), which is then degreased and decapitated. It is then sprayed with a mixture of liquid silver and reduction solution. The silver foil (mother) is removed and nickel-plated. The prints of the mother, called sons, are the finished press dies that are inserted into the record press. A press die can produce approx. 1000 records and has a thickness of approx. 200 micrometers.
The last significant technical innovation in record production was the DMM (Direct Metal Mastering) cut, which was launched on the market by Teldec/Neumann in 1981. Instead of acetate foil, an approx. 200 micrometer thick nickel layer is used on the blank, so the nut is cut directly. This eliminates the time-consuming and problematic silver-plating process and allows the sons to be made directly from the cut (prints). This saves resources, protects the environment and simplifies and speeds up the process considerably. Unfortunately, this technology was only introduced to the market shortly before the advent of the CD in music stores, which meant that very few cutting machines were built that were DMM-compatible. Due to the lack of availability of copper blanks, some of these machines were even retrofitted for lacquer cutting. Unfortunately, they are a rarity in the record industry.
Lacquer foil (l.) and DMM foil (r.)
Whether acetate or DMM was used for cutting only makes a difference in the preparation of the master, the nickel plating is identical for both variants. In the vast majority of cases, nickel sulphamate is used with the addition of boric acid in a strongly rinsed bath. The fabric is usually moved using a turntable to which the cut is attached.
As a rule, no brighteners or leveling agents are added. Wetting agents are usually the only organic agents used here.
The requirements for record electroplating differ from industrial electroplating in a number of ways, which we would like to discuss in more detail. For many electroplating applications, the adhesion of the applied layer is one of the biggest challenges. The vast majority of industrial coatings are subject to high demands on the durability and function of the deposited layers. Corrosion protection is usually the main focus here, as are appearance and feel. Good leveling is also a property that is often required by the electroplater.
In record electroplating, leveling is absolutely undesirable, as otherwise the grooves in the 50 to 80 micrometre width range cannot be reproduced precisely. Even minimal deviations lead to considerable tonal problems. Corrosion is also not a priority, as the prints are used close to production and are not exposed to the elements. However, the ductility of the haul-offs is very important, as the press dies have to withstand over 100 tons of pressure without breaking.
Process chamber with turntable
Grinding machine for the back of the press dies
Two-chamber nickel-plating plant for records
As several negatives are usually drawn from one workpiece, passivation is one of the biggest challenges for the electroplater. Any adhesion here leads to chipping of the grooves and thus to rejects. In a market with tight margins and short turnarounds, this is problematic. Potassium dichromate is usually used for passivation; however, due to the toxic properties of chromium(VI), alternatives are being actively sought. The use of protein-based passivations offers considerable potential here.
The most important requirements in vinyl record electroplating are therefore an accurate reproduction of the grooves down to the micrometer, perfect passivation and good ductility. Now that the vinyl record has experienced a renaissance in recent years and production figures are rising steadily, it will continue to provide interesting jobs for electroplaters for some time to come. Despite its widespread use and long history, vinyl record electroplating remains exotic in the industry, which makes it an interesting career alternative, especially for young electroplaters with a passion for music. In Germany, many pressing plants are still working on it every day and are always happy to welcome new recruits.
Despite its long history, record electroplating remains exotic
