Technique - Printing Archives - Page 3 of 3

Bronzing

Technique - Printing Comment

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Bronzing is an iridescent flash of color, typically bronze, produced when viewing prints under varying angles of light. It’s produced by pigmented ink’s tendency to refract light. It’s most visible in black and white prints but affects color prints as well. It affects glossy surfaces almost exclusively.

Optimum choice of ink and precise placement makes the difference. Recently, new separation routines and screening algorithms have been devised to place droplets of specific ink colors, in specific patterns, in combination with other inks to dramatically reduce bronzing.

How can you identify bronzing? Look at the surface of a glossy print in near direct light. Change the angle of the print and look for a flash of bronze near areas of glare.

What can you do to eliminate bronzing? Choose the best inksets and drivers. (Optionally, print on a matte surface.) This will all but eliminate bronzing in your prints.

Learn more in my digital photography and digital printing workshops.

Metamerism

Technique - Printing Comment

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Metameric failure is the tendency of an object to change its appearance under different light sources. Different light sources, even of the same color temperature, are often comprised of differing amounts of spectral frequencies (i.e. red or blue frequencies). Some objects change appearance more quickly than others; they are more metameric. This is true when comparing dye-based inks with pigmented inks. As pigments are made of irregular particles, they tend to refract (reflect and bend) light more strongly than uniform dye globules. The most current ink technology coats pigment particles in resin to reduce this effect. Additionally, some color pigments, typically the most saturated ones, are more prone to metamerism. By separating the file differently and using more of the less metameric ink to reproduce an image, the print’s appearance stability is increased. This is particularly important when reproducing neutrals, as small shifts in hue are quickly detected in these colors.

How can you evaluate metameric failure? Make two prints of the same image (preferably containing significant neutrals) and compare them side by side in different light sources.

What can you do to reduce metameric failure? Use the latest inksets and drivers (with the latest separation routines). And, when practical, standardize the light your prints are viewed under. Can metamerism be completely eliminated? No. Everything is metameric. But metameric failure in prints can be reduced to the point where it is no longer significant or noticeable.

With new technologies come new possibilities and new challenges. Recent advances in inkjet technology (ink formulation, separation routines, and screening algorithms) are making noticeable gloss differential, bronzing, and metameric failure things of the past. It pays to stay informed of the latest developments in printing technology. Your prints will simply get better.

Learn more in my digital photography and digital printing workshops.