Flexography

When You Need to Print on Cardboard or Plastic

Plate used in flexographic printing
Close-up view of a flexo plate at at Flexstar Packaging Inc. | Dale Simonson CC BY-SA 2.0 | Printing | Alpha Index to Full Dictionary:. # | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | XYZ

Flexography is a modern version of letterpress printing. It is a traditional method of printing that can be used on almost any type of substrate, including corrugated cardboard, cellophane, plastic, label stock, fabric and metallic film. Flexography uses quick-drying, semi-liquid inks. In this new age of digital printing, flexography is holding its own in the areas of large orders, particularly of packaging products and labeling.

Flexographic printing uses flexible photopolymer printing plates wrapped around rotating cylinders on a web press. The inked plates with a slightly raised image rotate at high speeds to transfer the image to the substrate. Flexography inks can print on many types of absorbent and non-absorbent materials. Flexography is well-suited to print continuous patterns, such as for gift wrap and wallpaper.

Unlike the individual sheets of paper used in offset printing, the rolls of material used in flexography allow large orders to run with few interruptions to reload substrate.

Advantages of Flexography

  • Extremely high press speeds
  • Prints on a wide variety of substrate materials
  • Low cost of equipment and maintenance
  • Relatively low cost of most consumables
  • Ideally suited for long runs
  • All printing, varnishing, laminating and die cutting done in a single pass

Disadvantages of Flexography

  • The cost of the flexo printing plates is relatively high, but when they are properly cared for, they last for millions of impressions 
  • It takes several hours to set up complex jobs that print, varnish, laminate and die cut
  • Takes a large amount of substrate to set up the job, potentially wasting expensive material
  • If version changes are necessary, they are time-consuming to make

Designing for Flexography

Like all types of printing, flexography has specifics relating to types of proofs, template and die cut specifications, issues with knockouts, drop shadows, fonts, tints, ink colors, image resolution and image formats.

The design and file preparation affect the quality of printing you get from flexography, so mastering its specific requirements—some of which differ from the more familiar offset printing—is essential.

For example, the minimum font sizes used for both positive and reversed serif or sans serif type is based on the type of web press and whether you are printing to corrugated coated paper, uncoated newsprint, polyester film or other substrates. For most purposes the minimum range is 4 point to 10 point type, but that is a wide range Sans serif type can usually be printed smaller than serif type, while reversed type is tricky to use in flexographic printing. 

For designers new to flexography, a visit with the printing company is essential to learn how to best structure a print project to avoid delays and errors.