Small type can affect the appearance of a package dramatically. A label may appear elegant on your computer monitor, but become hard to read on a jar label, the thin side panel of a box, or a small mockup file. Design of packaging calls for type to accomplish more than simply look good. The package should accommodate the product title, the flavor or style, a few short claims, the ingredients list, barcode information, and the entire back of the package, while keeping the overall package from looking over cluttered.
Start with the product title, which is generally the part of the type design requiring the most presence, as it informs the viewer what the product is. If a decorative or attention-grabbing font is used for the product title, supporting type should be calmer and simpler. If every line is bold or dramatic, nothing appears especially important. Most memorable package type uses one eye-catching choice and many simple, straightforward choices.
Rather than many font types, labels with small type really need font scales. Scale is what you want to emphasize by making one word the largest font, another word larger than the rest but not the largest, and the others in smaller fonts. On the front of the package, you might want the product title to be the largest, the product summary in medium font, and weight, scent, flavor, or short call-out text in smaller size. Back of the package, you need headlines to help you see the ingredients, directions, or the code. Scale without a scale causes the consumer to work too hard at understanding the hierarchy.
The type size matters less than the line-height. Letter-spacing that is too dense becomes blurry when small, and line-height that is too dense results in back panels reading as a solid gray field. Give supporting text plenty of line-height, especially on narrow labels and on the sides of the package. Maintain a safe distance between crucial words and the cut, fold, and bend area, which can make type harder to read on packages. Type that is beautiful and attractive is rendered useless when the surface of the package renders the type hard to read.
You should test your typeface in actuality instead of waiting until a final project. Make a mock-up with the product name, the brand name, one short sentence describing the product, and a couple of very small pieces of information. If you can, print at full size, or display on your screen at the size it would appear in the mock-up. Then, move back a few feet and see which words are visible first, which become difficult to understand, and which are too close to any other words. This is more effective in the long term than critiquing a package when it is large on your entire computer screen.
Color contrast can either enhance type design or quietly undermine the type. Type on the background of very light color, thin type over a very textured pattern, or delicate, low-contrast decorative type may be attractive but difficult to read. When in doubt, try product name type in black and white first. If the scale works in black and white, the palette serves to express mood, category, and shelf presence. If the scale is dependent on the existence of a single colored element, you have to rethink the overall design.
Legibility does not mean lack of typographic creativity. Legible packaging ensures the consumer is able to identify the product before seeing the details. A clear and readable product title, a calm set of supporting type, well-thought-out line height, and tested color contrast give designers more room to play. Before adding a new font, a new line of text, or a new graphical treatment, you should see if the package is already able to convey its message at the intended size.