There are many ways to create paint chipping effects, like heavy chipping using mediums and precise chipping made with a fine-tipped paintbrush. When you want something in between that provides more control but is less tedious, reach for the humble sponge.
What type of sponge should you use? Left to right: Makeup sponges are useful tools, but not for this technique. Large-celled sponges (kitchen and natural sponges) produce a looser pattern. Microcell foam found as packaging material makes a tighter pattern.

Tear off a piece of foam or sponge large enough to work with. An irregular shape is fine because it will expose several cells at different angles. Here, a bit of microcell foam shaped into a point will make the contact area smaller for more control.

You can hold the sponge material with your fingers, but that can be difficult to control. A pair of locking tweezers lend better finesse, or you can superglue the material to the end of a makeshift handle.

Any type of unthinned paint can be used for this technique. Dip the sponge in the paint and then blot it off on a paper towel. This ensures the cells aren’t filled with paint. You want a random pattern, not a blob of color.

Start in an area where you want more coverage to ensure the pattern is acceptable. Gently press on the surface and build up the effect slowly. Using different colors allows you to show chipping not only to the primer but the metal underneath.

Chipping can bring elements of a finish together. For instance, this door has a red cross on a white circle decal and some slight chipping around the edges. More chipping along with scratches made with a fine-tipped paintbrush makes the cross look naturally weathered.

Using a chunk of kitchen sponge produces a heavier pattern that works well along edges, handles, or locations that see frequent use.

Paint chipping with sponges can quickly create subtle, controlled effects. Don’t toss that old sponge or packing material, use it on your scale models. FSM