Make every line at least 1 pt thick (about 0.014", or a third of a millimeter) at the size the sticker will be printed. Thinner lines can break up into dashes or disappear altogether, and a hairline that looks crisp on a zoomed-in screen is usually the first thing to go.
The part that matters is "at the printed size". A 2 pt line drawn on a 6" design and printed as a 2" sticker becomes about 0.67 pt, which is under the minimum.
Lines that need more than 1 pt
- Light colors. A pale yellow or light gray line has little contrast to hold it together, so give it more weight.
- Reversed lines. Ink spreads very slightly into the space around it, which thins a light line on a dark background.
- Holographic, glitter, and chrome. The shimmer underneath competes with fine detail, so bolder lines read far better on these films.
- Lines near the cut. A thin outline close to the edge shows any small shift in the cut as an uneven frame. See why borders can look uneven.
Small text follows the same rule
Type fails the same way, because its thinnest strokes are lines. Our minimum is 6 pt, or 8 pt for thin fonts such as light weights and scripts. See fonts that survive printing.
Checking your design
Print it at actual size on an ordinary printer and look at it at arm's length. If a line is hard to see there, it will be hard to see on the sticker. Your proof shows the same thing, so look closely at fine lines there before you approve it.