What are Printing Plates and How are they Made?

Understanding the print production process, after you have sent us your PDF artwork, can be extremely helpful in planning certain elements of design to aid in a quality print result. One such process is separating your final artwork into CMYK, + any spot colours, to create press/printing plates. In this blog we discuss what Printing Plates are, how they are made and the role they play within the print production process to create full-colour images.

Our 5-Colour Press, viewing the Cyan Colour Station showing a plate being ejected.

Print-Ready Artwork

After you approve your print-ready artwork proof, the file is split into each CMYK primary colour*; Cyan, Magenta, Yellow and Black. Note* Additional plates are made when spot/pantone colours are used, like metallics or for Spot Machine Varnishes. These 4 x CMYK colours (plus spot if applicable), printed on top of one another produce full colour images. You can view these "Separations" within your artwork using InDesign or Adobe Acrobat as shown in the below example. Click to scroll through each separation example below; The full colour image, C - Cyan , M - Magenta , Y - Yellow and K - Key/Black ...

View of Artwork in CMYK

View of Artwork in CYAN

View of Artwork in Magenta

View of Artwork in Yellow

View of Artwork in Key (Black)

Plate Setting

We then use these colour separated files to transfer the images onto aluminium plates, one plate for each colour, using a Plate Setter Machine. Many Plate Setting processes use chemicals, water and gums, however at Printcraft we are proud to use environmentally friendly Kodak Sonora Process (Chemical) Free Plate technology.

The Kodak Sonora Process Free Plate technology removes the need for water and chemicals by using a thermal direct process to burn away the coating on the non image area's of the plate, leaving the image areas to which the ink will stick to. In other words, for a Cyan plate, the Plate Setting process will burn away the plates coating in all area's except where Cyan Ink is required.

If for example a printed project is only black and yellow, only two plates (2 Process Colours) would be required; Yellow and Key (Black). Where there are an array of colours requiring C,M,Y and K plates, this is referred to as 4 Colour Process, requiring 4 plates to be made.

At Printcraft we currently have 2 x 5-Colour Offset Heidelberg Presses and 1 x 8-Colour Heidelberg Offset Press. While there are many possible combinations offered by these impressive commercial printing presses, some examples of plate sets up are;

• A 5-Colour Offset Press running a 4 colour process (CMYK) + a Pantone/Spot Colour

• A 8-Colour Offset Press running a 4 colour process (CMYK) + 1 or more Pantone/Spot Colours plus an overall varnish on the same pass, like a full colour product catalogue with 2 Pantone Brand Colours.

• The 8-Colour Offset Press also offers the efficiency of being able to print a 4-Colour process on both sides of the paper at the same time, this is called Perfecting.

One of two Printcraft Plate Setters using Kodak Sonora Process Free Plates

Printing On The Offset Press

When the finished plates come off the Plate Setting Machine, the images appear as off white and can barely be seen until they've been used on the printing press and come into contact with the ink.

On the Press, the plates is inserted into its corresponding colour station where it is wrapped around the plate cylinder. Inside the press there are 3 cylinders:

• Plate Cylinder

• Blanket Cylinder

• Impression (or Coating) Cylinder

View of the Plate Cylinder as our new 5-Colour Press was being installed.

As the Plate Cylinder turns, ink is applied to area's of the plate which are NOT burnt away during the Plate Setting Process. This inked image is then transferred to the Blanket Cylinder as the paper substrate passes through between the Blanket Cylinder and the Impression Cylinder. As the paper passes through each of the C,M,Y,K colour stations, the image is built.

This in itself is in-fact why it is called "Offset" Printing, because the paper does not actually come into direct contact with the plate cylinder, but rather is transferred from the plate, to the blanket, to the paper; building the image on the paper, one colour at a time.

What happens to the plates after a printed project is finished?

Kodak Sonora Plates on our New Speedmaster Offset Press

Fortunately, printing plates are made from the purest form of aluminium and since they are not in use for extended periods of time or have a complicated shape, they are infinitely recyclable. Commercial printers around the world have been recycling their printing plates for many years contributing to the circular economy.

Printcraft are proud to further contribute to the environmental sustainability of our industry by using Kodak Sonora Process Free Plates which...

• Eliminate chemical processors and the subsequent chemical waste produced through clean-up and disposal.

• Eliminate the need for water typically otherwise used in processing and cleanup.

• Use far less energy than other plate setting processes.

• Reduce waste in the press room both with less plate defects and fewer make ready sheets during press set up.

For more information on Printcraft's Commercial Printing capabilities or perhaps our digital services suitable for smaller volumes, get in touch with us or pop-in for a tour!

Some interesting facts about Printing Plates:

How many plates does Printcraft create per hour or day?

In a typical month we will produce around 5,500 plates and at top speeds, both machines can produce 80 plates per hour! During November 2021 our Plate Setting Legend, Margie, processed 7,530 in one month!

How many long will a single plate last during the printing process?

Printers refer to this as "holding the dot" for which they can generally do for around 80,000 sheets. But this is not the case for offset stock or where there is a complex screen in the image. For example a project with a great deal of one colour, lets say green, printed on an offset stock; we would likely need to change plates every 20,000 sheets as the screen would fill in too much and "lose the dot". For more about how dots make up an image see our video: A simple guide to understanding CMYK vs RGB

Printcraft is 100% Australian owned and family operated since 1982. That's 40 years supplying quality print, mail, digital and logistics services to our clients. We would love to work with you too.

Contact us for a no obligation chat about your next project.