How is screen Screen Printing of CDs done?
What options are available for CD DVD label printing?
What are the issues with Inkjet Printing of CD/DVDs ?
Why are film required?
What is Computer to Plate (CTP)
What is a 4 color process printing?
What are Negative and Positive films ?
What is Film Separations?
What are Pantone or PMS colors?
How can I be sure the color will be exactly what I want?
Whats the difference between RGB and CMYK artwork ?
What is Digital printing ?
What is a Proof ?
What options are available for CD DVD label printing? There are two types of printing processes. In most cases silk screen-printing is used for the printing of CD's, but offset printing has become more affordable over time. Gestetner offers screen printing from one to five colours as well as offset or Litho printing for printing of CD and DVD surfaces.
Screen-printing
Artwork is supplied to us in the form of Positives for CD. Each colour will require a positive, which results in each colour having its own silk screen. Ink is pushed through the mesh/ silk screen onto the disc using a squeegee. The ink is then cured and is then passed on where the next colour is applied forming a durable surface.
Picture discs are made up using five colours, which are, white, cyan (C), magenta (M), yellow (Y) and black (K).
Offset printing
In the case of offset printing negatives are used instead of positives. These negatives are exposed on to plates one for each colour, which are then fitted to the offset machine. Ink is then transferred via rollers to the plates and then to the discs.
Offset printing offers a higher quality print often used for photographic images. Offset Printing requires process colours to be used (CYMK).
What are the issues with Inkjet Printing of CD/DVDs ? Inkjet printed discs provide a similar looking effect to an offset printed disc but with the advantage of being able to be produced in low volumes. However, what many people do not realise is that whilst inkjet printing is both fast and cheap, it will also result in an unprofessional looking finish unless the print is effectively sealed with a chemical substance.
This is because the inks used in inkjet printing of discs are water based and as such are liable to smudging across the surface of the disc, destroying what is otherwise a nice looking product. Whilst some companies do lacquer and seal their discs, many do not as the chemical process involved can be expensive and hazardous. If you are considering purchasing discs with on-body inkjet printing, be sure to verify that the discs are sealed prior to placing your order. Gestetner is fully aware of the problems with inkjet printed discs and as such will only offer thermal printing or laser printed labels on duplication runs to guarantee our customers a high quality product.
Why are films required? Films are produced by an imagesetter from the artwork. They are used to produce the printing plates by a photochemical process. There is one separated film for each ink used.
Film Image Setter is a expensive printer that uses mylar film acetate sheets instead of paper. Once your digital files are preflighted (checked for bugs) a post script file is created and sent down to the image setter. Out pops film negatives.
What is Computer to Plate (CTP) Direct-to-Plate technology literally does what its name suggests: transfers images and type directly from an electronic format to the printing plate. Because shooting, stripping, and other film processes have been eliminated, customers can hold on to their files until the eleventh hour, making changes easily and quickly.
What are Negative and Positive films ? Usually you will find two different types of film used in a Optical Disc production. Film positives for disc label face printing using silk-screening, and film negatives for the paper parts using offset printing. The film transfers the information to the printing plates.
Gestetner uses direct to plate technology for most of its paper parts productions but still uses film positives and negatives for silk-screen and offset disk printing respectively.
Film positives simulation :  
Film negative simulation :
Film negative labeled
CYAN:
 
Printed Result
What is a 4 color process printing?
Four Colour Process Printing
The most common system for producing full colour print.
The vast majority of magazines and colour books are produced using four-colour process. Originally the artwork and originals were separated photographically using filters to produce four printing plates. Today the separation is carried out digitally.
The four ink colours are Cyan (Blue), Magenta (Red),Yellow and Black - often referred to as CMYK. Because the inks used are translucent, they can be overprinted and combined in a variety of different proportions to produce a wide range of colours.
What is Film Separations?
Films are not colored. They each look the same and all appear to be using "black" as their emulsion. The same way a black and white laser works, films come out of the printer one sheet at a time. They are simply "emulsified" or printed with dots in the area that needs that particular color or tint. This is know in the industry as a percentage of, or density information, for each color being printed.
A standard offset web press used to print booklets uses Cyan, Magenta, Yellow and blacK ink rollers. In order to make the CMYK printing plates we first need to break down images into the 4 primary colors in preparation for making film negatives (or positives for a CD label)
CMYK printed one on top of the other 
Final print.
You will see that picture of the girl has been split into 4 channels of information. If we then send this information to an image setter, out will come our 4 pieces of film. These 4 pieces of film are converted to printing plates and mounted onto a CMYK offset press. When the 4 plates are combined onto paper, the image is reassembled in all its glory.
How is screen Screen Printing of CDs done?
In the silk-screen machine, the CD slides effortlessly along a conveyer system and stops under a yellow sheet of synthetic material (fabric mesh) for each color needed. A squeegee then drags ink across the disc's surface.
In the past real silk was used as the mesh but advances in synthetic materials have increased reliability and reduced cost. The old name stuck around and we still call it silk-screening.
What is Offset printing
A technology that has been around for over 100 years now, the term "Offset" gets its name from the fact that the plate cylinder which holds the art information does not come in contact with the paper.
Step 1 Making negatives: The first step in the offset process is to create a negative from the original art. From this negative, a printing plate will be made.
Figure 1 below represents a digital file; Figure 2 is created inside the image setter. 
Step 2 Printing Plates: The negative is then placed in contact with a metal printing plate (fig. 3 below), which is coated with a photosensitive, ink-receptive emulsion. It is exposed to light and the plate is developed, leaving the only where it was exposed.
Step 3 Wetting: The plate is first moistened with water. This keeps the non-image areas damp, and therefore more resistant to the oil-based inks used in this process. The plate is now ready to be inked.
Step 4 Inking / Offsetting: After the printing plate is developed, it is attached to a cylinder on the printing press. As it turns, the plate offsets this inked image to a rubber blanket, creating a reverse image. The blanket then offsets this image to the paper, reversing it again and making a "right" reading, final print.
Step 5 Multiple Passes to Achieve Full Color: 
Multiple colors are accomplished by changing the color of the ink in each station as it passes through the press. Modern presses not only have 4 color stations but also add a varnish coat to help eliminate fingerprints on the paper.
What are Pantone or PMS colors?
The brand name of a color matching system produced by Pantone, Inc of the USA . A large range of inks are specified and identified by number to produce standard results across the industry.
Also called spot color or premixed inks, these inks are used for printing a specific corporate or accent color. Spot color inks are useful for colors that process (CMYK) printing cannot adequately re-produce. 
Typically it is harder to print CMYK on a disc face and easier to print SPOT colors.The opposite is true for paper parts as print shops all use CMYK as standard inking.
So when do you use spot color on the CD face? Always - unless you have been quoted for 4 color CMYK CD face printing, you want to guarantee the color tint for corporate logos. When three or fewer colors are needed and you will not be reproducing full color photographs. And finally when you want clarity in text and crisp lines and when you want a metallic effect.
How can I be sure the color will be exactly what I want?
For artwork with pretty solid color, meaning a large area with the same color, you can specify a Pantone number to make sure the color you mean will be the same color we will print. Designers and printers around the world use Pantone Matching System (or PMS for short) as the common ground.
For example a PMS 485 is the exact same shade used by designers and printers anywhere in the world. The PANTONE name is known worldwide as the standard language for color communication.
Pantone chips are usually used to compare the accuracy of a color. It is worth remembering that Pantone inks provide a much greater range of colours than can be achieved using CMYK.
Whats the difference between RGB and CMYK artwork ?
It is very rare that a computer monitor will display accurately the color chosen in your layout or in Photoshop. A lot of time money, time and effort is spent in tweaking systems so that visually the monitor will display as close to possible the printed page. Keep in mind that the two processes are totally different.
Red, Green, and Blue are "additive colors". If we combine red, green and blue light you will get white light. This is the principal behind the T.V. set in your living room and the monitor you are staring at now. 
Cyan, Magenta and Yellow are "subtractive colors". If we print cyan, magenta and yellow inks on white paper, they absorb the light shining on the page. Since our eyes receive no reflected light from the paper, we perceive black... in a perfect world! 
What is Digital printing ?
A recent development has entered the market in the shape of digital printing. These systems work directly from electronic data and avoid the intermediate stage of films. They are very cost effective for short runs. The quality obtainable is not yet up to lithography standards but is improving steadily and is adequate for many purposes. Because these systems use an inherently four colour process there is no cost saving to be made from using one- or two-colour designs.
What is a Proof ?
A proof is a test print produced to show what the finished product will look like. These can be made in a variety of different ways and at different stages of the production process. The simplest form is a color laser or inkjet print which can create a rough impression. It should be remembered that at this point there are still a number of stages through which the data has to pass and therefore a laser print cannot be relied upon as an accurate proofing method.
Increasingly popular are digital proofing systems. They are essentially very high-resolution color printers, which make use of color management techniques for their accuracy.
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