Structural Steel and Surface Tolerant Coatings

Ideally use ST before the degree of rust formation becomes excessive.

ST systems applied to minimally prepared surfaces are only suitable for atmospheric service conditions.

Sigmacover ST systems are suitable for immersion in water if the surface preparation is blasting to a minimum of SSPC 10 (ISO Sa 2 1/2).

They are then a good alternative to coal tar epoxy systems.


Sigma Surface Tolerant products may be the only materials required for factory maintenance - the almost infinite colour choice available in SIGMACOVER ST enables minimum purchase and stock, minimum cost.

Wash down old paint, almost any old paint, scrape off loose and wire brush away rust, patch prime and then full coat with SIGMACOVER ALUPRIMER or ST.

SIGMACOVER ALUPRIMER can even be used in immersion conditions if the steel has been sand blasted.


*Mill-scale, the bluish oxide layer formed on hot-rolled steel, is brittle, only partly adherent, and cracks on cooling. It is cathodic to steel and promotes corrosion at the cracks.

In time the corrosion spreads under the intact mill-scale which gradually flakes from the steel surface.

Abrasive blasting is generally used to remove mill-scale on new steel before painting for the first time.

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