Use of plumb line in drawing

Question from Gilberto

In a previous art school I attended, I was told about the use of plumb lines to help in my drawings. I’ve never got to use one; in fact I’ve never seen a drawing plumb line before, thus I do not know the technique for such instrument in drawing.

What is a plumb line and how could I use it properly for the drawing, say, of a live model?

Hi Gilberto,

Many thanks for your questions about use of plumb line.

The short answer:

If you are a professional artist, you don’t need a plumb line. If you’re just learning to draw, you should not use it, so you can instead develop your measuring-by-eye skills.

Use of plumb line in drawing:

A plumb line is just a piece of thread with a weight attached to its end. By holding such a line and aligning it visually with a model, an artist can measure vertical lines and the alignment of elements.

In the photo below, you can see how a plumb line is used to measure the sculpture of David.

The thread goes through model’s center of gravity, showing that David’s head, the middle of his chest, his navel, and the middle of his pubic bone are located on the same vertical line that further goes through his supporting foot. We can also see that the knee is offset to the left, while David’s eye is positioned immediately to the right of this line. Needless to say, such an alignment should be expressed accordingly in the artist’s drawing, if it is done correctly.

A vertical measuring line can be positioned at any point, not just through the middle of a body. For example, aligning it with David’s elbow helps to establish how far his left foot is from that location.

Why it is better no to use a plumb line:

If you aim is to become a proficient fine artist, then drawing aids will not help you achieve your goal.

You need to develop and rely on your drawing skills, not tools. Tools can be taken away; your skills always will be with you.

There are some art teachers and ateliers that advocate using helping aids such as plumb lines, measuring sticks, grey-scale values, compasses, rulers, etc. Although such tools will make the job easier, they will ultimately do you no favors.

Here’s an example that illustrates the point vividly. When you were learning to walk as a young child, your parents knew that crutches would hold your body upright and make walking easier. Nevertheless, they wanted you to walk on your own. Walking is a vital skill, and they wanted you to learn it well. Using crutches, ultimately, would only handicap you. In the same way, using drawing aids will limit your progress in learning the necessary artistic skills.

How to measure by eye:

Instead of relying on helping tools, you should train your eyes and hand to draw proficiently.

Even the untrained human eye can detect a deviation from a vertical line as small as one degree. That’s more than enough for precise drawing.

Here is how to develop your skills in measurement-by-eye. First, draw a vertical line on your paper, bisecting your drawing wherever you like. Then, compare this virtual line with the model by using your pencil. Extend your hand, holding the pencil vertically, and align it with the model. Check what points pencil intersects on the model and how that relates to the drawing. Fix any mistakes in your drawing if necessary.

With practice, your ability to measure by eye will improve. Your drawing process will seem like “magic” to observers who can’t understand how you mentally measure lines, angles and proportions! Such a skill will serve you for the rest of your life, and it cannot be taken away like a plumb line.

I hope this clarifies your questions about the use of plumb line in drawing.

Kind regards,

Vladimir London
Drawing Academy Tutor