If you are releasing a CD or DVD whatever the content you have probably searched the internet for a company to do this for you. You will be bombarded by hundreds if not thousands of sites offering replication and duplication, is there a difference and does it matter? The answer to this is yes although if using a reputable company the end result (and the most important) is that the disc can be read as intended. So, what is the difference and which method should you choose?
Before you decide which method to choose or even understand the process involved you need to decide on a few factors before production is started.
1. What is the run length you require?
2. What is the time scale you have to produce the product in?
3. Does the aesthetic appearance matter?
4. How much do you want to pay per disc?
CD and DVD replication
Okay, first off with replication. Replication is mainly a mechanical way of producing the disc. When you buy software music or films from a shop this is the way they will have been produced. This method is best suited for runs over a 1000 units and can run in to the millions.
So how does the process work? First off the data is burnt via a laser onto a glass plate which is coated with a photosensitive material, you will often hear the phrase ‘glass master’ this is the first stage in the process. Once the glass master is finished a metal stamper is grown via electrolysis from the plate, it physically has a track with pits in that eventually the laser in the player will read when the disc is completed.
Once the stamper is made the glass plate is recycled for use in the making of different stamper. Depending on the run length several stampers could be made, the typical life of a stamper is around 30,000 units. The stamper is then put into an injection moulding machine and the image is physically pressed into molten optical grade polycarbonate under a pressure of around 30 tons. You could liken this to the way vinyl records are made but on a much smaller scale. The disc then is taken out of the mould and allowed to cool is a controlled manner so that it doesn’t deform. The disc contains the opposite image of the track and pits that the stamper had on the top of the disc. If you were to take a look at the disc now you would see a clear piece of plastic and you would just be able to make out the data that had been pressed into it. This is so fine that if you were to rub your finger across the disc it would be totally destroyed. The next stage is to produce a reflective layer that the laser in the player can use, this process is called spluttering. The disc enters a vacuum chamber that has an aluminum plate at the top and a magnet at the bottom, a puff of argon gas is inserted and an electrical charge is applied this causes the surface of the aluminum to atomize and a plasma is formed. This is then drawn down onto the disc buy the magnet. The disc exits the chamber and is coated with a UV varnish to protect the disc and stopping the aluminum from oxidizing. The disc is then ready to be printed and packaged. The lead-time in producing a disc this way is normally 10 to 12 working days.
CD and DVD Duplication
Duplication is the process of burning the data onto a blank CD-r or DVD-r exactly the same way as you would do in your PC but instead of doing them one by one bulk copiers are used. As this process is a lot simpler the run lengths can be a lot shorter as little as one could be done. Also the lead-time will be a lot shorter. In a lot of cases the copying can be done on the same day depending on how many burners the company you use has. In fact some companies can burn many thousands in a day. Another advantage is if the artwork to be printed on the disc is ready before the data to go on it they can be pre-printed and burnt when the data becomes available, this is impossible with replicated discs. The only disadvantage with this process is that you can tell it is a CD-R or DVD-R as the recording surface has a hue to it this is a organic dye that the laser burns the data into and some people take a dislike to this even though it will play the same. You can get around this with CD-Rs by using diamond discs which used a silver dye and is almost impossible to tell the difference unless you know what you are looking for.
Advantages of replication
Longer run lengths can be produced
More cost effective.
Disadvantages of replication
Not cost effective on short runs
Lead times 10 – 12 working days normally
Advantages of Duplication
Cost effective on short runs
Lead times from 1 day upwards
Disadvantage of duplication
Not cost effective on larger runs
People might not think it as professional as a replicated disc.