by R. Harvey Bravman
There is more than one printing option available for media replication. When selecting a facility to produce your project, their ability to both offset and screen print on media is important. There are situations where offset or screen-printing is best, and the project requirements, rather than a replicator's abilities, should determine which method is used. No single format fits every project.
Technical Differences Between Offset and Screen Printing
The first step in the screen printing process is burn the images from the electronic artwork on to film positives. During the process, ink is pushed via a squeegee through a fine mesh screen onto the disc.
With offset printing, the image is burned directly onto printing plates. Rollers push ink onto the printing plate and then the image may be transferred to the disc's surface. This is essentially the same process as offset commercial printing on paper or board.
Offset Printing Considerations
- Offset printing is more cost effective on runs in excess of 5,000 units. Set-up time required to offset print is greater than that for screen printing, forcing most plants to add an up-charge for runs under 5,000 units.
- Offset printing provides better results for more complex artwork, such as photographs, gradations, or images using percentages of colors.
- For most projects, matching the media label printing with it's packaging is vital to the project's appearance. This is a job for printing experts. The two biggest challenges in matching print are surfaces and printing process.
- Printing on different surfaces is an unavoidable fact of media replication, and varied surfaces yield variations in print. A DVD absorbs ink differently, for example, than a cardboard package.
- Most large quantity paper and paperboard packaging is printed offset. It is much easier to match an offset-printed media label to offset-printed packaging. Using the same printing format for media and packaging is the best way to ensure consistency in your final product.
- Offset prints 175 line screen and requires at least 300 DPI artwork. The higher line screen produces a smoother surface.
- Most offset projects are printed 4-color process with a white flood coat. While the appearance of an image created under 4-color process screen printing can be degraded by the line screen (this happens with areas of solid color, for example), this is not an issue for offset printing. Complex images as well as solid colors reproduce boldly under 4-color process offset printing.
- Offset tends to dull because the process inks are transparent and a higher resolution is used.
- Offset printing involves additional setup steps unnecessary in screen-printing. These steps can sometimes impact a project's delivery date.
Screen Printing Considerations
- Runs as small 1,000 can be produced without an up-charge.
- It is easier to custom match a particular color with screen printing. Any PMS can be printed, and it is even possible to mix PMS colors. Some PMS colors do not have representative CMYK equivalents, such as the 180-190 ranges of red or the 280-290 ranges of blue. In these cases, printing the specific PMS color is better for optimum results.
- Metallic and fluorescent inks can be used in screen printing. Some corporations and institutions have their own proprietary colors. These colors can be purchased for screen printed projects.
- Solid colors using 4-color process artwork do not print as well in screen as in offset.
- The average line screen is 133. Due to the lower line screen, the surface is not as smooth.
Proofing Print Media Printing Projects
Most jobs use PDF files as the project proofs. These are not fully accurate for color, but they do accurately show image placement.
Print check discs are another way to assure the quality of your project. This is a data-free CD or DVD that accurately reflects how the final product will look. Print check disks cost roughly $300 and will add three to four days to a project time line. For this reason, they make the most sense for larger runs. In fact, printing for runs of 50,000 units or more should not start until the client approves a print check disc.
About the Author
R. Harvey Bravman is the owner of Advanced Digital Replication, Inc.; offering a full range of state-of-the-art CD and DVD replication/duplication as well as media archiving services since 1998.