GEOMET® ( is a coating made with an aqueous base and is composed of zinc and aluminium flakes in an inorganic binder.

GEOMET® is chromium free (no hexavalent chromium nor trivalent chromium) and environment friendly. GEOMET® performances linked to corrosion protection and lubrication are particularly high.


GEOMET is a sacrificial coating that ensures the protection of metallic surfaces thanks to:

Barrier protection - Overlapping zinc and aluminium flakes provide an excellent barrier between the steel substrate and the corrosive atmosphere.

Galvanic action - Zinc corrodes to protect the steel.

Passivation - Metal oxides slow down the corrosion reaction of zinc and steel to provide a greater corrosion protection than with pure zinc.


GEOMET® 321 is a non-electrolytically applied thin-film coating of metallic grey colour for the corrosion protection of parts made from steel, cast iron, or other iron metals. GEOMET® 321 is composed of zinc and aluminium flakes in an inorganic binder; it has been developed by DACRAL S.A and is a chromium-free product. The GEOMET® 321 coating is obtained by the application of an aqueous dispersion by cold immersion or spray and is therefore free of any risk of hydrogen embrittlement.


  • Weight: > 24 g/m² 
  • Thickness: A 6-8 μm
  • Salt spray test (ISO 9227): > 600 hours without red rust > 200 hours without white rust


  • NO HYDROGEN EMBRITTLEMENT: The non-electrolytic application of the film does not induce hydrogen embrittlement. GEOMET® 321 is therefore especially suitable for protecting safety parts.
  • RESISTANCE TO AUTOMOTIVE FLUIDS: GEOMET® 321 tested according to VDA 621-412 provides a satisfactory resistance to standardised test fuel, diesel fuel, motor oil, organic solvents, cooling fluid, brake fluid. The coating also resists to an immersion for 24 hours in brake fluid at 80 °C.
  • DUCTILITY: sufficient for elastic deformations of springs, clips etc
  • ELECTRICAL CONDUCTIVITY: GEOMET® 321 has a sufficient conductivity for all the applications.
  • HEAT RESISTANCE: GEOMET® 321 keeps its mechanical properties up to 300 °C, which is the tem-perature needed for the binder formation. For applications above 300 °C, specific tests are necessary. Its resistance to salt spray test exposure is not modified by a prior exposition of the coated articles for 100 hours at 180 °C.
  • PAINTABILITY: GEOMET® 321 may be covered by most organic coatings. Due to the laminar structure of the coating, the cross-hatched adhesion test is not adapted.
  • THROWING POWER: the application on parts by cold immersion allows for the total covering of the internal surfaces, for example screws with captive washers, clips, tubes.


GEOMET® 321 may be used in all industrial areas for the protection of ferrous metals by appropriately selected application techniques. It is especially suited to fasteners. In the automotive and truck industry, OEM specifications must be respected. In industries with no specific standard, the BS EN ISO 10683 and EN 13858 can be used. The standards describe requirements for zinc-flake coatings. Related information can be found on the website