Traditional Blue Line

The traditional standard in the printing industry has been the DuPont Dylux monochrome proof, also called a blueline. A blueline is a photographic contact print of plate-ready negatives, which make it a composite proof. A blueline proof is relatively inexpensive and is produced using a photosensitive paper with the same specifications of the jobs signature that turns blue when exposed to ultraviolet light. Bluelines can be two-sided and can be folded and stapled (if required) to represent the physical features of your printed, finished piece.


Bluelines are used to check:

• Text and headline placement
• Halftone cropping size
• Placement and size of rules, reverses and tints
• Page sequence
• Crossovers and backup
• Scores, perforations and drills
• Trims, fonts and binding

Blueline Process

As a printing job progresses from concept to press, the proofs take longer to make. They represent the finished product more accurately. You also pay more to make changes. Many production managers use the 5-50-500 rule: It costs $5 to correct a mistake on a computer, $50 to correct the same mistake when discovered on a blueline and $500 when it's found on an overlay or laminated proof. To correct an error found during a press check requires time and money. "We never considered the importance of the lowly blueline. People never pay attention to things like that. We didn't know what we had till it was gone. While the blueline has always been intended mostly as an imposition proof, it's taken on a huger life in practice. We found our customers were constantly using it for copy reading. They'd order one set of Matchprints and five bluelines that would go to account people, copy proofers, even some of the mechanical artists checking a number of different things."