Line drawings are quick, and they communicate a lot of information. Make sure your linework is communicating the right information by following these guidelines.

Good lines are clear. The viewer knows exactly how your product looks in the real world. When they look at a line they can tell immediately whether it is the edge of a form, or something on its surface. They never have to guess what a line is showing.

Bad lines are vague. The viewer has trouble imagining your product in the real world. They can’t tell product edges from surface details. They may have to guess where the important lines are and what they are showing.


Underworked and Overworked Lines

Lines often go bad because the designer is worried about the drawing. They may rush past a difficult section, leaving the lines too vague and too light. Or they may draw it again and again, hoping to find the perfect lines, but making a mess in the process.

Underworked lines happen when you avoid something difficult. You want to draw a difficult shape, but you’re not sure how. So you barely sketch it, and hope that the viewer’s mind will fill in the blanks. The result is a sketch that’s hard to see. It hints at a shape, but it never clearly defines anything.

Overworked lines happen when you repeat yourself. The first line you draw doesn’t look right, so you draw another. That one isn’t perfect either, so you draw another, slightly darker line…and another…and another. Soon you have a wide, dark line with fuzzy edges. The correct line is in there somewhere, but it’s hidden among all the incorrect ones.

To avoid either of these problems, start with a series of light construction lines. If you’re drawing with a pencil (or any other medium that gets darker when you press harder) press as gently as you can. If you’re using markers (or anything that only draws in one color), use the lightest marker you can see without straining your eyes. For me, that’s 20% gray.

Before you draw a single dark line, make a light sketch of your entire product. Start with the overall forms, to make sure you have the right proportions and perspective. Then focus on the tricky parts (also known as “the parts that worry you” or “the parts that you’re likely to overwork”).

Every time you draw a line, ask yourself if it’s looks right. If it does, move on to the next one. If it doesn’t, draw a new line, but don’t make it any darker than the first one. Keep redrawing these light lines until you have the one you want. Once your construction lines are complete, go back over your sketch and carefully make the correct lines darker.


Dark Edges, Light Surface Details

Line weight can tell the viewer a lot about the objects in your drawing. Dark, thick lines usually represent the edges of a form, while thin, light lines represent surface details. So make sure that your line weight is giving viewers the right information.

Look at each line in your drawing, if it’s on this list, it should be dark and thick.

  • The outer edge of a form
  • The line where two (or more) forms overlap
  • Tthe border between two different parts of a product

If it isn’t on this list, it’s probably a surface detail. It should be significantly lighter and thinner than the lines above.