Each medium, CD, DVD, mini-CD, mini-DVD or blue ray, can be duplicated (burnt) or replicated (with glass master).
The duplication (burning) is a writing process of data on recordable media performed through extremely precise and reliable industrial burners, able to verify copy by copy the exact correspondence between the original data supplied by the customer and the ones written on the duplicated medium. No plant is needed and so this technique is extremely indicated for short run duplication up to 300 copies.
The replication (glass mastering) is a very sophisticated industrial process, by which we can obtain pre-recorded discs. In fact unlike burning, that writes data on recordable media, with replication the discs start with the data already pre-loaded. The replication process is very complex. The first step is the realization of the glass master, that is a glass template with a diameter of 24 cm, on which the data of the original disc to replicate are recorded.
This sensitive operation is performed in special white rooms with controlled temperature and atmosphere.
Once created, the glass master is covered with a thin layer of silver and then plunged in a galvanic tank and covered with a nickel layer.
At the end of this process, the resulting nickel disc is separated by the glass master, obtaining in this way the “stamper”, that is the matrix than will be mounted on an injection press and then used to produce copies.
Once obtained the “stamper”, begins the real production phase, during which the raw material (polycarbonate in granules) is dried and then melted at 320°C, then it’s injected in the press on which the matrix had been mounted.
With a mechanical process, the polycarbonate is pressed on the matrix, forming a transparent disc and cloning the data contained in the matrix.
Then the disc is covered with a thin layer of aluminium, that will serve as reflecting surface for the laser light during the reading process.
In the end on the aluminium layer is spread a film of UV lacquer to protect the disc, that now is ready to be tailored with offset or silkscreen printing.
The replication with glass master is recommended for industrial productions and is utilized for at least 300 copies.