What colors can be printed on on colored film?
Bold, colorful designs can really make a bag stand out, but it's important to follow some basic guidelines to get the best results.
All ink colors print well on white film, so if your art has multiple, or bright, colors, the colors will always look great on white. Most inks - with the exception of white, black, and metallic colors - print translucent or even transparent. This causes the print to pick up the color of the film, or to disappear completely - especially on dark film. For instance, Blue ink on yellow film will become greenish, yellow ink on black film disappears completely, and red ink on beige or buff film will become burgundy. Predicting how different inks will appear on different film colors is also very tricky, and is highly dependent on the ink formula of the chosen color. White ink looks good on dark colors, but picks up the film color slightly. On black film, white looks slightly gray, on navy blue film, white looks light blue, etc.
We match ink colors using the Pantone PMS Formula Guide. Pantone makes several color guides, with values for matching colors in different uses. RGB and Hex color values are used for computer displays, where colors are created by mixing red, blue, and green light. CMYK definitions are for process printing, where tiny dots of Cyan, Magenta, Yellow, and blacK inks are printed in varying amounts to emulate the final color. Flexographic printing uses spot color printing, which means different base ink colors are mixed to match the color desired. The Pantone Formula Guide provides the recipe for different color mixes.
As an example, a popular red color is PMS 185, which has a formula of 75% Warm Red ink, and 25% Rubine Red ink. This prints bright red on white film, but on black film it completely disappears because both Rubine Red and Warm Red are transparent inks.
So, is it possible to make bright colors show up on dark film? Yes, but predicting the outcome can be very tricky. There are two ways to get transparent inks to print on dark colors: 1) put a white backer behind the colors. This will provide a lighter, neutral base color which will provide a light base for the colors to print on. The downside of this is the necessity for an additional printing plate, and higher printing costs. Because white prints translucently, the final print will still be hard to predict. 2) choose a color that has at least 50% white in the formula. The downside is that the color will print translucently and the color of the underlying film will show through, and the results are impossible to predict with accuracy.
If we use PMS 185 Red again as an example, a close color match with white ink in the mix is PMS 7625, which has a formula of 27% Rubine Red, 26% Yellow 012, and 47% White. This makes a red that is close to 185, but has enough white in it to provide some opacity. But again, it is impossible to predict how it would print on darker film colors.