BS EN ISO 4623-1:2018 pdf free

BS EN ISO 4623-1:2018 pdf free.Paints and varnishes – Determination of resistance to filiform corrosion
type of corrosion proceeding under a coat of paint, varnish, or related product, in the form of threads,generally starting from bare edges or from local damage to the coating
Note 1 to entry: Usually the threads are irregular in length and direction of growth, but they can also be nearly parallel and of approximately equal length. They usually follow the extrusion direction and do not cross over one another. They need to be initiated by aggressive ions.
Two alternative procedures are available, based on initiation by dipping in sodium chloride solution or by exposure to salt fog. The dipping technique is generally preferable for air-drying and low-durability materials. For high-durability systems such as automobile finishes applied to phosphated steel, the dipping technique may not produce filiform corrosion and for these systems it is preferable to adopt the salt fog technique. In such cases, the necessary period of exposure to salt fog will depend on the durability of the material under test but should rarely need to exceed 4 h. It should be noted that salt fog exposure is not normally suitable for low-durability materials since with such systems it commonly produces heavy general corrosion spreading from the scribed marks and the filiform corrosion is suppressed.
Immerse the scribed test panels for 30 s to 60 s in the sodium chloride solution (8.1).
Take the panels out of the solution and remove any drops of liquid remaining on the surface, taking care not to remove the solution from the scribed marks.
Place the panels in the test cabinet (7.1) maintained at (40±2) °C and a relative humidity of (80±5) %.Repeat the immersion procedure, as specified above, every 3 or 4 days until the end of the specified test period.
Where appropriate, at the specified intervals of re-immersion and on completion of the test, inspect the test panels for filiform corrosion (see ISO 4628-10). Do not allow the test panels to become completely dry at any time during the test period or during inspection, as this may affect the development of the filiform corrosion.BS EN ISO 4623-1 pdf free.