Humera Fasihuddin
Project Engineer
Rexam Graphics
South Hadley, Mass.

For years, engineers have relied on software, printers, and inks to give their designs that professional look. But few realize the important role paper plays in the overall quality of their final output. Choosing the right paper for the job can mean the difference between a colorful, eye-catching design and a bland and blurry mess. It could also mean the difference between winning and losing a bid.

A variety of paper or substrates have been formulated to enhance computer-generated designs. They offer varying levels of precision, water resistance, and color capabilities. For best results, the paper, ink, and hardware must be carefully chosen to work together.

Plotters put ink on paper as dots. Dot size is measured in microns and is heavily dependent on the ink and printer. If the paper is not specifically optimized for the ink and printer, dots can be inconsistent, poorly absorbed, or the wrong size — and all of these degrade the final image.

Ink dots often cause problems on uncoated paper. The dots can be too large, making them bump into each other and creating color bleed. They can also be too small and cause banding (a pinstripe effect appearing throughout an image). There can be too many dots, leaving too much ink and creating cockle ( a wavy effect) in areas such as titles, solid fills, and gradations in title blocks. And dots can seep into the paper fibers, bead up on top of it, or bounce off of it, leaving colors dulled.

Coated paper, which has a barrier sealing the surface from the fibers, usually makes for precise, round ink dots that sit close to the paper’s surface without being absorbed. Coated papers also don’t yellow with age as much as uncoated paper. Coatings are usually aqueous-based solutions and vary in thickness according to what inks the paper is to be optimized for. Optical brighteners are also used to make the paper brighter and whiter, and to give images more contrast and vividness. A few coated papers use a backcoat to prevent them from curling due to changes in humidity.

Here is a list of some of the papers and other media available for printers and plotters:

High-resolution coated inkjet paper is ideal for fine-line drawings needed for electrical schematics, mapping, and technical drawings. Some high-resolution coatings provide water resistance for plots that will be handled often or exposed to the elements.

Heavyweight presentation-grade coated inkjet paper is durable, stiff, and easy to use. It can be laminated to give presentations a professional look, or left unlaminated. They can also be used for color or monochrome plots that have full coverage.

Inkjet vellums give excellent results in almost all circumstances, from color plotting to diazo reprinting. They are strong and durable, can handle high-density plots, and have been used by engineers as reproduction masters. Although most designs on vellum are black and white, some users print color renderings on color vellum because they make for better diazo reprints. (The diazo process differentiates colors in shades of grey, black and white.) And some manufacturers offer vellums designed for color or monochrome plots.

Translucent papers are made for monochrome plots and drawings and are considered a low-cost alternative to vellum. Some have lower opacities for more light transmission, making them well-suited for making diazo reprints. Others are more opaque for dual use as both bond and translucent. These sheets can be used for blueprints or as a check print and as working copies during a design project. Vellums and translucents can be coated to optimize for specific inks.

Ink jet films are optically clear, sometimes made of polyester, and are designed for color plots such as overlays, complicated wiring systems, or plumbing diagrams. Unlike fiber-based papers, films don’t wear or tear with normal use, and they don’t expand or contract with changes in humidity. Their dimensional stability makes them good choices for applications where precision and accuracy are required. When working with films, it helps to have the proper type for the job (and ink). Otherwise, there can be problems with long drying times, along with tackiness and smearing. And always be sure to use the coated side of the film to make sure the ink dries properly.

Double-matte films, which have a matte layer on the bottom side, produce superior images with the highest resolution. Some matte finishes are erasable, allowing users to make corrections by drafting on the matte surface beneath the ink-jet layer.

Photobase papers give users matte or glossy photorealisitc finishes and extremely vivid and clear colors. They are often used for client presentations and proposals.

It’s important to use media designed for your specific application, whether that’s making diazo masters, fine-line drawings, check plots, or full-color presentations. It will give you brighter images with more accurate and precise lines. And, remember, for the best results, the media must work together with the inks and hardware.

© 2010 Penton Media, Inc.