When you think of paper, you probably think of the simpler aspects, such as dimensions, color, stock, and the like. However, paper opacity is another quality that may have occurred to you without knowing exactly what it is. In short, paper opacity measures how “see-through” the paper is, or its translucence. Translucence allows light to shine through without being completely transparent.
Paper opacity isn’t based on something as simple as paper thickness—there are thin paper stocks that block light as well as thicker kinds that allow some light to show. So, what does paper opacity measure, what are its effects, and how can different types of opacity benefit you and your projects? Use this ultimate guide to paper opacity for beginners to help you out!
Paper Opacity: Making Out the Details
As mentioned, paper opacity is all about how well the paper keeps light from passing through, measuring the ratio of reflectance. Reflectance is “the measure of the proportion of light or other radiation striking a surface which is reflected off it.” Manufacturers test paper by reflecting light off its surface. They then measure the ratio of reflectance off a sheet, first with a black backing, then with a white backing. The paper opacity measurement that follows comes from TAPPI T425 standards, measured by using industrial measuring devices known as opacity meters.
Opacity is the percentage of visible light that doesn’t show through the paper. Fifty percent opacity, for instance, means that 50 percent of the light can’t show through. It is otherwise obstructed, absorbed, or reflected by the paper. The greater the opacity, the less light comes through, and vice versa. To use non-paper examples, imagine the difference in translucence between a concrete block and a bottle of olive oil. You can’t see through either, but one lets more light through than the other.
Why Does Paper Opacity Matter?
All well and good, but how does this affect paper and, more importantly, your choice of paper for your projects? Translucence may not be a major concern for most projects. Businesses typically print on one side of posters, billboards, and similar displays, and the materials they print on are usually opaque. Likewise, business cards, postcards, and similar items feature ink printing on one side and not the other.
However, projects printed on both sides of the paper can present an issue. Books, catalogs, brochures, pamphlets, and similar projects that require printing on either side need to have a high enough opacity to allow for easy reading without sacrificing flexibility or allowing the printing on the other side to show through. It is possible, of course, to achieve all that.
Methods and Materials
Some papers are opaque due to their cellulose content—that is, the vegetable fibers derived from trees and other plant sources, and the microscopic spaces between them. Cellulose makes the paper denser and thicker, scattering light and making it less translucent and more opaque. However, there are other ways to reflect light besides thicker, denser paper.
- Assorted coatings can make ordinarily translucent paper less so. Applying these coatings ensures the surface reflects or absorbs light, depending on thickness or darkness.
- Rough and textured finishes can also help, making what are ordinarily smoother stocks less translucent and more reflective.
- Colored stock of various shades of darkness is also good for improving paper opacity.
Those are just a few methods for ensuring lighter, thinner, and similar paper stocks prevent unwanted light from interfering with the images and messages they carry.
Things To Remember
In preparing the ultimate guide to paper opacity for beginners, we couldn’t forget to include a few tips and tricks for making your projects really stand out.
Vellum Suits Certain Projects
Consider whether greater translucence can help a project. There may be a case for including a document or flier on vellum paper, which allows greater light to shine through. Vellum also has more gravitas than typical papers and can add an element of elegance to your messaging.
Color Brightness and Opacity
The brighter your design gets, the higher opacity paper you should use. High-opacity paper makes colors vividly stand out and gives a better presence to the design through greater saturation.
The Intricacies of Coatings
Coating can protect and prevent text on the other side from peeking through. But if you pick a paper that’s sufficiently thick, you don’t need coating. Coating can also dull colors and graphics, so use it sparingly.
To Gloss or Not To Gloss
Go glossy for slickness and sleekness, but reconsider glassy opaque paper if you’re trying to appear more professional in your design. Gloss can also make paper positively reflective, which can make interpreting images and reading text harder.
Testing Inks
Test inks for transparency! This step is a good thing to discuss with your printer. Some inks react well with some paper stocks while others don’t. Inks can be transparent and translucent as well, so discuss the best choices for the job and do test runs with different inks to see how they look and work with various papers. Opaque inks exist too.
Layering for Effect
Layering one kind of paper on another can also produce different effects, but it is especially good for preventing more translucent papers from revealing their “secrets” on the other side or allowing light from either side to interfere. Programming the printer to layer different inks atop one another can also produce greater opacity without worrying about the paper. Experiment with different papers, inks, and techniques!
Consider the Nature of the Lighting
Look for the light! No matter the project, you should always take time to scope out the place where it will be and gauge the lighting situation by using a light meter. Observe how the sun and nearby electric lighting will play off large-scale prints. Opacity is just one element to watch for. For smaller pieces—circulars, brochures, and so forth—keep average light levels in mind, whether the reader reviews the project in direct sunlight or under a desk lamp’s light.
Have questions about paper opacity and how our printers, papers, and printing supplies can help? Contact us for a consultation! We offer high-quality plotter paper for sale as well as other goods and services.
