Drawing the Light that Shines Through (or Doesn’t!)

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Observing how light behaves on surfaces is key to drawing transparent, translucent, and opaque objects.

By Margaret Davidson

One of the basic visual properties of any object is whether it’s opaque, transparent or translucent. When you look at an object, your eye can determine this instantly. For example, consider the three glasses in Illustration 1, below. You can discern without difficulty which contains milk (center, opaque), water (at left, transparent) and apple juice (at right, translucent).

You’re able to tell the difference so quickly because your eye immediately takes three factors into account: how light behaves on the surface; whether you can see through the object and if so, how clearly; and the shadow the object casts.

When drawing transparent, translucent, or opaque objects, you can depict the level of opacity by paying attention to these factors, as Illustration 2 shows, below. Consider how you draw the light shining on the object, how clearly you draw what’s showing through the object from behind and how you treat the shadow the object casts. Doing so will reveal an object’s transparency, adding subtlety, complexity and accuracy to your drawing.

Opacity

An opaque object is one that cannot be seen through, whether solid or liquid. It’s the easiest of the three categories to draw. We draw opaque subjects all the time: wooden furniture, pottery, walls, floors — the list goes on. Opaque objects can be shiny or dull, and the highlight is the the most direct way to convey these properties.

The highlights on shiny surfaces tend to be distinct shapes with sharp edges. They look like white shapes surrounded by a much darker tone, with no gradation between the two. In Illustration 1, above, the straws and glass of milk are examples of shiny opaque objects.

Dull things are the opposite, with highlights that are soft and blurry around the edges. The highlight on a dull object is still brighter than the values surrounding it. But the highlight blends gradually into the surrounding tones, without discernable edges. The stones in Illustration 3, at the beginning of this article, are examples of dull, opaque objects.

Whether shiny or dull, all opaque forms block light from traveling through them. This results in solid cast shadows that have no interior light. I draw cast shadows soft around the edges, but I make the interior of the shadows plain and dark.

Transparency

A transparent object is one that can be seen through clearly. The most obvious way to indicate transparency is simply to draw something showing through from behind the object. For example, in the case of a lake, you can show rocks under the surface. In Illustration 1, above, we see the striped background through the transparent glass of water, although there’s distortion from the curve of the glass.

We see another transparent object in Illustration 4, below: a Japanese glass fishing-net float. The horizontal background line is visible through the glass object, although there’s even more distortion because the float has more curvature than the cylindrical water glass.

Transparent objects are usually shiny, so they often have sharp-edged highlights. The shadows they cast are slightly tricky to draw, but they are one of the most telling and descriptive features for indicating transparency. The cast shadow of a transparent object is full of light, because light passes through the object and right into the shadow. When you draw that light-filled shadow, draw just what you see.

The light within the shadow is not quite as bright as a highlight, so make the light within the shadow a little bit darker than, say, light shining directly onto a tabletop or wall. That slight darkness indicates that the light did pass through something and was colored by the experience.

Translucence

Translucent objects fall between opaque and transparent. Light passes through them, but we can’t clearly see through to the other side. Translucence is the most complicated of these properties to draw. Show translucent forms as indistinct, with softly fading edges and vague contours. The techniques for creating soft edges take longer and require more careful strokes.

What’s visible in the background, showing through a translucent object, varies according to the level of translucence and the distance between the object and what is behind it. Apple juice, for instance, is fairly dense, whereas lemonade is less so. Both are translucent but to varying degrees. Translucent things can have sharp-edged highlights, as we see on the apple juice in the clear glass, or softer highlights, as on the plastic container in Illustration 5:

The cast shadows of translucent objects have a tinge of light within them but not as much as seen in the cast shadows of transparent objects. Translucence changes depending on the location of the light source. A translucent object will often appear opaque when lit from the front or side (see Illustration 6, below). The light falls between the two groups of grapes, so the front cluster is lit from behind, while the back cluster is lit from the front.

The back grapes show highlights and shadows in the same intensity and positions as they would if they were opaque. The front cluster shows the translucence of each grape, with the interior seed faintly visible and a small amount of light in the cast shadows.

A Quiet Success

Drawing these properties convincingly will give more truth to your imagery. It is, however, a quiet success. Like many good realism skills, when done well it becomes invisible. Everyone believes the drawing and moves into the world you’ve created without question — and without noticing your careful attention.

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Margaret Davidson is an artist, illustrator, and former teacher at the Gage Academy of Art in Seattle. She is the author of Contemporary Drawing: Key Concepts and Techniques (Watson-Guptill, 2011).

A version of this article was published in Drawing, Winter 2017.