In case the metal profiles are protected by an unknown primer, it is necessary to determine whether it is possible to apply fire protection over such a primer.

It is necessary to do following tests:

• adhesion test that determines if the primer resists detachment from the substrate
• compatibility, ie. check whether the primer will remain glued to the substrate (metal surface) and to the fireproof coating in case of fire

If the thickness of the primer is equal to or greater than 90 microns, the adhesion and compatibility must be examined in detail.

Tests of both characteristics can be done in the so-called "cold" and "fire" conditions. Test results in "fire" conditions are relevant when tests are conducted within accredited laboratories.

Adhesion in "cold" conditions

This test checks the chemical compatibility between the coating (primer and FP coating) as well as whether in the conditions of regular operation of the facility the adhesion would be maintained at the required level. Commonly used methods are:

• cross-cutting and
• tearing by tightening.

There are international standards that detail these techniques.

Cross-sectional test: