Sprayed-metal coatings

Steel surfaces can be sprayed with zinc or aluminium or with a mixture of both in various proportions. The environmental conditions to which the coating will be subjected will determine the choice of spraying material. In marine and coastal areas aluminium is normally preferred.

Before spraying, blast clean the surface with grit abrasive to the highest standard - BS 7079 Part 1 1989 SA3. The selected metal is sprayed through a special gun which melts and atomises the metal.

As a result of this process a coarse porous profile can be produced. If high-performance coatings are sprayed on to this surface the result will be pinholes and blow holes caused by entrapped air and solvent vapour.

Metal-sprayed surfaces must first be sealed with a thinly sprayed non-saponifiable sealer prior to the application of the recommended system primer.

Modified etching primer

Can be used to seal the surface and provide a good key for priming. It also protects the metal-sprayed surface from the atmosphere preventing 'salt' formation prior to the application of the specified coating system.