How to Verify a Supplier's Salt Spray Claims

Four questions for every claim

1. Which standard? ASTM B117, ISO 9227, GB/T 10125 and GB/T 1771 are related but not identical.
2. On what substrate? Steel, aluminium and coil samples behave differently.
3. At what film thickness? A thicker panel film lasts longer than the coil will.
4. Judged how? “No red rust”, a blister rating and a scribe-creep rating measure different failures.

Why our own numbers are not ranked

The table above shows the PG results as supplied. They come from different standards and different failure criteria, so 2,000 h is not “better than” 800 h in any meaningful sense. Each figure is useful only against another result measured the same way.

Ask for the report

A test report should give the laboratory, the report number and date, the sample description and photographs at the inspection intervals.

What this means for your project

When comparing suppliers, ask all of them to quote results to the same standard and criterion, or ask for tests on the same basis. The test data page lists the standard for every PG figure.