Duplication Vs Replication

Often confused, duplication and replication each have their pros and cons

To put it simply, duplication involves burning each CDR or DVDR one at a time and replication refers to the process where CDs or DVDs are manufactured by the injection moulding of raw poly carbonate. The data on replicated discs is “stamped on” at the time of moulding and not burnt on as is during duplication.

The first step in replication is the creation of a glass master from which the “father” is created. This glass master is not to be confused with a data image of the disc, it is a physical representation of the pits that make up a data layer, made out of glass. This then in turn is used to create a “mother” or stamper. This mother then acts as the mould for the polycarbonate to be formed. In large volume runs several mothers are made in order to spread the production across a number of lines.
The finished discs are then metalised to protect them, and then printed using either litho or screen printing.

During duplication, recordable discs (similar to the ones you may burn on a home PC) are first printed using one of a number of print methods such as Litho, Screen or Digital. These pre-printed CDR or DVDR blanks are then duplicated or burnt one at a time on either automated duplicators or towers containing as many as 11 burners and one reader. Despite modern burners and media attaining speeds of in excess of 40X for CDR and 16X for DVD it is more common for professional duplicating companies to limit the write speed to 16X for CDR and 8X for DVDR. This helps create a more reliable copy and reduces wastage during the duplication process.

As the print options for recordable DVDR and CDR are very similar to those available for replicated discs it is sometimes difficult to spot the difference between the two if only looking at the print side. However the data layers of most recordable discs have a very distinctive appearance, with DVDR typically being a dark purple hue and CDR often a pale turquoise or slightly see through silver. Replicated discs however, both CD and DVD, have an aluminium coating applied to the data layer for protection which gives a solid metal appearance to this side.

Although duplicated CDR and DVDR are sometimes difficult to tell from a manufactured CD or DVD it is still the case that a retail product needs to be a replicated disc. This is partly down to the fact that the durability of a replicated disc is greater than that of a duplicated disc but also from an anachronistic idea that a recordable disc is somehow not as good as a replicated one. It is true that when recordable CDR and DVDR where first launched there were playability issues which were not present with replicated discs, but in the last few years the technology has improved greatly to the extent that the playability differences between replicated and duplicated discs are so small as to be insignificant. So much so in fact that many critical projects which are not for retail use, such as financial reports and film award submissions are duplicated and not replicated.

The usual rule, if a disc is not for retail, is that if the discs are required quickly or the quantity is less than 500 units then the duplication route is taken. Conversely if the lead time is not an issue or volumes are significantly higher than 500 units then the disc is replicated.