Matte things like an apple, a clay pot or a cotton shirt show soft light that turns gradually into shadow, as in Highlight, Core Shadow and Reflected Light. Shiny and see-through things play by the same rules but look very different.
- Shiny: small, sharp, very bright highlights; strong contrast; crisp reflections of the window, the lamp and the table.
- Glass: you see what is behind it, slightly bent or shifted, plus a few bright edge highlights and some dark edges.
Key idea
Shiny things show sharp highlights and reflections with strong contrast. Glass shows what is behind it, slightly bent, plus a few bright and dark edges.
Why it works
A matte surface scatters light in every direction, so its lit side looks evenly bright. A shiny surface reflects light mostly in one direction, like a mirror, so you see a crisp, bright image of the light source and of the room. Glass lets most light through, and its curved surface bends that light, which is why things behind a glass look shifted or enlarged. The Science Lab's optics page shows how light reflects and bends.
Worked example: A glass of water
How do you draw a clear drinking glass on a striped tablecloth?
- Draw the ellipses of the rim and base and the sides, lightly.
- Draw the stripes you see through the glass: they look shifted and wider.
- Add the darker edges where the glass curves away from you.
- Leave the paper white (or lift with an eraser) for a few crisp highlights on the rim and side.
Answer: Draw what you see through it and on it, not a gray glass shape.
Common mistake
People often outline a glass with a dark line and fill it with gray. Glass is not gray; it is mostly what is behind it. Draw the background through the glass, the edge darks and the bright highlights, and the glass appears.
Keep your brightest whites by planning them: leave those spots of paper untouched from the start, or lift them out at the end with a kneaded eraser.