Dacromet 320/500 Coating

DACROMET 320 is a an aluminium-grey, non-electrolytic, thin coating for anti-rust protection of steel, cast iron and other ferrous metal parts. It is composed of thin zinc and aluminium plates in a chrome oxide mould. Dacromet 500 also has an integrated lubricant

DACROMET 320 is a non-electrolytic water-based thin-film coating for the corrosion protection of articles made from steel, cast iron, or other iron metals. The coating contains zinc and aluminium flakes in a chromium binder. The coating is metallic silver in appearance.
DACROTIZING is the process whereby the aqueous dispersion is applied by cold immersion or spray and is therefore free of any risk of hydrogen embrittlement. The coating thus produced is passivated throughout the film and provides high performance corrosion protection


The corrosion resistance of DACROMET 320 depends upon the thickness of the coating and is due to the combination of several mechanisms :

  • a barrier effect due to the tile-like structure of the film,
  • controlled sacrificial protection of the zinc in relation to the metal substrate,
  • the film passivation which reduces the speed at which the zinc and aluminium are consumed Coating Thickness

Two coating weights are commonly used to meet the automobile industry’s requirements :
Grade A : coating weight > 24 g/m², average thickness 5 to 7 µm
Grade B : coating weight > 36 g/m², average thickness 8 to 10 µm
Greater coating weights may be applied to increase the duration of the corrosion protection


  • No hydrogen embrittlement : When surface preparation is done according to recommended techniques, the non-electrolytic application of the film does not induce hydrogen embrittlement. DACROMET 320 is therefore especially indicated for protecting security parts.
  • Corrosion resistance : DACROMET 320 meets all automobile manufacturer specifications for the corrosion protection of mechanical parts. It is also very well suited for numerous other applications such as building, civil engineering, railway equipment…
  • Resistance to automotive fluids : “standardised test fuel, diesel fuel, motor oil, organic solvents, cooling fluid, brake fluid: no coating alteration (VDA 621-412). Immersion in brake fluid for 24 hours at 80°C: no coating alteration.”
  • Ductility : Sufficient for elastic deformations of springs, clips
  • Electrical conductivity : DACROMET320 is conductive. It allows for use of electrodeposited paints.
  • Heat resistance : DACROMET 320 is cured at 300°C , thus providing excellent heat resistance.
  • Paintability : DACROMET 320 may be covered by most organic coatings and in particular, those applied by electrodeposition.
  • Throwing power : The application on parts by cold immersion allows for the total covering of the internal surfaces.

Application Field

When choosing the coating process best suited for a given application, DACROMET® 320 may be used in all industrial areas, for all types of metallic parts


DACROMET 320 is specified and used by all automobile manufacturers, and numerous other companies.


Several application techniques are used industrially by DACROMET Licensees according to particularly ecological methods specified by DACRAL :

  • dip-spin in bulk : the parts are cleaned, immersed in baskets into the DACROMET 320 bath, spun to eliminate excess material, then dried and cured at 300 °C . The operation is performed at least twice to obtain the desired level of protection.
  • dip-drain-spin on racks : the parts are attached to racks. The procedure is the same as for bulk applications.
  • Dip-drain : for parts too large to be spun.
  • Pneumatic or electrostatic spray or high-speed bell : DACROMET 320 lends itself particularly well to these application techniques.