One of the more frequent calls to our Technical Hotline comes from frustrated printers seeking a solution to marking and scuffing on matte coated stock. Often, they wrongly assume that they are experiencing an ink drying problem. The problem unusually shows up after finishing when a lot of time and money have already been expended and there is no opportunity for a quick recovery.
Matte coated papers are popular with designers because they lend a traditional, almost antique look to photos that a glossy finish does not. They’re not vulnerable to being marred by fingerprints and they produce non-glare text and photos that are easy to read. The tradeoff is that matte paper has poor rub resistance. Although paper and ink makers are aware of the problem, it has been difficult to eradicate.
Matte paper has a low degree of gloss, as low as 10% based on the gloss Tappi measurement, but more commonly 25-35%. To achieve the matte appearance, coarse pigments are used in the coating layer, which helps disperse light in all directions. The goal is to reflect little direct light, which is why calendering is not used in the production of matte paper. Calendering is the process of polishing paper with steel rollers under great pressure to create a hard, gloss finish (rather than the “soft” finish of matte papers).
The challenge of the papermaker is to manufacture a paper surface with a high macro-smoothness to promote good printing characteristics and a low micro-smoothness in order to obtain the diffuse reflection of light essential to matte papers. It’s these properties that result in lower rub resistance—matte papers can be “burnished” by rubbing a fingernail repeatedly over the same spot until a gloss area appears. The high micro-roughness can also lead to faster ink absorption. If it occurs too quickly the ink vehicle may take some of the resin with them, leaving ink pigments on the surface with little resin to protect and hold them.
Sealing the printed image with a matte varnish or coating is the only certain way to prevent marking on a matte sheet. Unless overprinted with a varnish or coating, matte stocks should not be used for applications that expose the printed image to friction or excessive handling. Choosing an ink that has been formulated for matte stocks may reduce the incidence of marking, but will not always eliminate it. If using UV inks is an option, they will offer better rub resistance than conventional inks.
While matte paper is aesthetically pleasing, its selection requires good communication between the designer and printer so that rub resistance issues are addressed upfront in light of how a piece will be used. Switching to a dull or satin stock, for example, might still meet the designer’s need for a low-gloss sheet (although glossier than a matte sheet), while providing somewhat better rub resistance. This straightforward communication will go a long way to preventing a frustrating experience for the printer and disappointment for the customer.