The string technique is a system we’ve been using in class to help us understand the visual relationships between objects. This method is useful for determining the relative size of your subject, and also for seeing the position and angle of an object. The string technique helps you to simplify what you’re looking at to lines and units, so that you can understand your subject better in terms of what you’re actually seeing, instead of a schematic of what you know it’s supposed to look like.
Standing in the same position every time, you hold one end of the string taut in each hand at arm’s length with your elbows locked and one eye closed. You should have each end of the string on the same vertical plane. When you’re drawing, you’re trying to translate a 3D object into two dimensions, so you want the string to look like a 2D line superimposed on your subject.
To use the string technique to see size relationships between parts of your subject, you “pinch out” a length of string that is the same length as a part of your subject from your perspective. This creates a unit that you can use to measure other parts of your subject. Ideally, you’ll find that some part of your subject is equal in length to the unit you’ve created, or a multiple thereof. In the above photo, I measured the lip of the plant’s pot and found that it was the same length as the dried leaf and the stem it hangs from on the lower left. Then, I doubled that unit, and found that it was the same as the height of the green onion from its emergence from the soil to the point at which it bends. This length also corresponds to the length of the portion of the green onion from the point at which it is visible below the lip of the pot to the kink in the stem toward the bottom. So:
1 lip of the pot = 1 dried leaf = ½ green onion from the soil to the bend = ½ green onion stem from the pot lip to the kink
Finding sets of relationships like this is massively helpful for keeping a drawing in proportion. If you can relate one thing in the drawing to lots of other things, you have a lot of useful information to use any time you wish to confirm that your drawing is in proportion.
Using the string technique to create units makes perfect sense to me. In my spare time, I like sewing and knitting. I often have no idea of the actual size of a piece of fabric I’m cutting—I just know that it’s twice the size of another piece, minus the seam allowances, and it’s cut at the same angle. When I’m casting on to knit, I’ll often cut the loose end to the length that I want the finished object to be, and sometimes I’ll measure that out by folding the loose end across the width of the object multiple times, until I’ve measured out the desired ratio of width to height. Once I related the string technique to the way I do crafts, it helped me realize that my visual units don’t need to be “real” units—feet were originally based on someone’s foot, and meters have been variously based on the distance to the North Pole and the distance traveled by light in a vacuum in 1/299,792,458 of a second. Are “chair-seat lengths” or “dried leaves” really that much more arbitrary, especially when we’re dealing with a chair or a plant?
To use the string technique to see an angle more clearly, you hold the string and rotate it so that it lies tangent to the line you’re trying to see. This makes it easier to shut down the part of your brain that knows how the subject is supposed to fit together so that you can see how it truly looks. You can then attempt to draw that angle, followed by a repetition of the measurement so that you can compare what you’ve drawn to what you’re seeing.
For example, before I used the string technique to look at the angle in the picture below, I believed this stem was much more vertical than it is. I know that the basil plant is a bit tilted, but this brought home the degree of the tilt.
With curved objects, it’s a bit like taking the derivative of a function in calculus. You’ll have to use the string to find a lot of angles in order to understand the curve this way. When I first started looking at organic objects using the string technique, I was very strongly reminded of this Khan Academy exercise, which is intended to increase intuitive understanding of derivatives by allowing you to manipulate the tangent lines visually. This is a very good exercise to practice some of the same skills involved in the string technique, even if you don’t understand the math involved. It’s the same sort of thing that we’re doing in class—creating and manipulating a line on an image that we’re trying to understand—but it’s more systematic (it’ll tell you whether you’ve gotten the slope right mathematically), and it’s a lot easier to visualize a line tangent to a curve when the curve is just another line, instead of existing as part of an object.
I’ve been surprised by how much a simple piece of string has helped me to think in terms of what I’m seeing, instead of what I know to be true about an object. There are lots of objects that I understand in an IKEA manual sort of way—this part connects to that part at a right angle, and so on—but I have had a hard time seeing them in the way that my brain is receiving the raw visual information. I tend to think of human beings as strongly visual animals, but there’s this layer of pre-interpretation getting in the way of just seeing things. It’s been fascinating to shut that down, even for a few seconds.