# Cratering (fish eyes)

Source: https://coatmentor.com/defects/cratering/ · Updated 2026-10-14

Small round holes or dimples where the wet paint has pulled away from a spot, often with a raised rim.

*Figure: Cratering (fish eyes): the surface as you see it, and a schematic cross-section.*

## Causes

- Oil, grease or silicone on the surface.
- Oil or water in the compressed air supply.
- Contaminated spray equipment.

## Prevention

- Solvent clean (SSPC-SP 1) before blasting and painting.
- Check the compressed air with the blotter test (ASTM D4285).

## How it is assessed

Visual inspection; trace the contaminant to its source before work continues. Craters in a pattern along the spray passes point to the air or the equipment; craters in patches point to the surface.

## Telling it apart

- **[Pinholes](https://coatmentor.com/defects/pinholes/):** Pinholes are tiny holes that go deep into the film, often where air or solvent escaped. Craters are wider round dimples where the paint moved away from a contaminated spot.
- **[Crawling and cissing](https://coatmentor.com/defects/crawling/):** Crawling pulls the paint back into beads or islands over a wider area. Craters are separate round spots with a rim.

## Repair

Clean off the contamination, abrade and recoat the affected area. The specification and the coating manufacturer have the final word on the repair procedure.

**6** practice items in the members area mention cratering (CIP 1: 1 · CIP 2: 1 · FROSIO written: 4).

## Related

- **Concepts:** [Surface cleanliness grades](https://coatmentor.com/learn/surface-cleanliness/)
- **Standards:** [ASTM D4285](https://coatmentor.com/standards/astm-d4285/) · [SSPC-SP, NACE No. and WJ](https://coatmentor.com/standards/sspc-surface-preparation/)

## 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](https://coatmentor.com/method/). CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.