Coating defect

Overspray

A rough, sandy or powdery layer of dry spray particles on nearby steel, at the ends of spray passes and on adjacent members.

Overspray: the surface as you see it, and a schematic cross-section.

Causes

Spray gun too far from the surface, or atomizing pressure too high.
Fast-drying solvent, heat or wind.
Poor access to the area being sprayed.

Prevention

Keep the right gun distance and pressure.
Mask or protect nearby surfaces.

How it is assessed

Visual and by touch. Overspray landed outside the target; dry spray is the same dry, pebbly texture on the target itself.

Telling it apart

Dry spray: The same dry, pebbly texture on the target surface itself is dry spray.
Contamination and inclusions: Inclusions are foreign matter in the film. Overspray is paint, landed where it was not meant to go.

Repair

Brush and wipe off fresh overspray; sand or abrade cured overspray smooth before the next coat. The specification and the coating manufacturer have the final word on the repair procedure.

19 practice items in the members area mention overspray (CIP 1: 8 · CIP 2: 2 · FROSIO written: 9).

Try it in an exam-style question. The free readiness check shows the question style, explains every answer and gives you a dated study plan.

Take the free readiness check See the tracks

About this page

Written from coating practice and the published rating standards, in our own words; the drawing is schematic. Checked on 2026-10-14; errors go in the corrections log. CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.