paint soluble salts

Soluble salts:

Definition: Chemical compounds that dissolve in water to form an ionic solution.

Soluble salt contamination of surfaces to be painted are considered harmful, in the sense of reduced coating system durability (blistering and/or corrosion damage). Salt species generally receiving most attention are chlorides; also sulfates and nitrates.

Soluble salts are invisible at potentially harmful surface concentrations. Tests to determine contamination levels usually involve extraction (from the surface) into a solution, with subsequent chemical analysis of the solution. The so-called extraction efficiency needs to be considered in this approach.

Possible sources of soluble salt contamination (selected):

Airborne: marine environments, de-icing operations, fertilizing, fossil fuel combustion, industrial chemical processes, natural phenomena, etc.
Handling: fingerprints, perspiration.
Coating constituents: deliberate additives or degradation products.
Pre-treatment and surface preparation: abrasive (contaminants in), salt residues, inadequate rinsing, rinse contamination, etc.
Corrosion products: soluble species (inadequate removal of).

References/Literature:

Links:

Paint degradation under influence of water