The shadow family (core, form, cast, contact/occlusion)

You can tell apart core, form, cast, and contact shadows, and place each on purpose to keep forms solid and grounded.

What it is

Shadows aren't one flat blob of dark — they split into types. The core shadow is the band where a rounded form turns most away from the light. It sits just past the light-shadow edge and is usually the darkest part of the object. Form shadow is the whole area facing away from the light — the core plus the softer darkness around it.

Cast shadows happen when one object blocks light from hitting another surface. They belong to the caster but lie on the surface they hit. Their shape describes the caster's silhouette, and their edges get sharper or softer depending on how close that surface is to the caster and how sharp the light source is.

Contact or occlusion shadows sit where two surfaces touch or come very close: feet on the ground, a cup on a table, folds touching in cloth. They're usually the darkest, most compressed values in a scene because almost no light bounces in there. In painting, place these as tight, small accents that lock objects to the surfaces they rest on and separate layers that would otherwise merge.

In practice, you can look at any dark area and ask: is this the surface turning away (form/core), the object blocking light onto something else (cast), or two surfaces meeting (contact/occlusion)? Then paint each with the right shape, edge, and value: broader and softer for form shadows, shaped and directional for cast shadows, tight and punchy for contact shadows.

Why it matters

If you treat all shadows as the same mushy dark, forms cave in, characters look stickered onto the background, and lighting feels fake. Missing or weak contact shadows make objects hover; missing cast shadows erase the story of where the light comes from; missing cores make volumes look flat and airbrushed. Once you separate the shadow family and paint on purpose, volumes feel solid, weight shows up, and your light direction becomes obvious and believable.

You can check it when

• ✓You can point to any dark area in your own painting and label it as core, form, cast, or contact/occlusion shadow — and you're usually right when you compare to reference.
• ✓You can adjust just one type of shadow (for example, strengthening only contact shadows) and see a specific effect: better grounding without flattening the whole value range.
• ✓Your cast shadow shapes match the silhouette and position of the caster, and their edges get softer as they move away from it or into foggy/atmospheric space.
• ✓Your contact shadows are small, controlled accents at touch points, noticeably darker than nearby form shadow, and they make objects stop looking like they float.

Related skills

• Cast shadows (direction, softness)
• Source size → hard vs. soft light
• Bounce/reflected light and ambient occlusion
• Separating form edges from cast-shadow edges
• The light family (halftones, highlights, speculars, reflected light, terminator)
• Separating the light family from the shadow family
• Plane analysis and turning form with value