How

How does a Zinc Coating Prevent Corrosion?

Zinc Coating protect steel from corrosion in two ways.
Zinc coating becomes a barrier for the corrosion substance to reach to the base metal under the zinc coating.
The layer of Zinc sacrifice itself and gives anodic protection to the surface where the metal(steel) is exposed to the atmosphere due to the scratches.

Therefore, Zinc coating gives the base metal a long life and corrosion protection in any atmospheric condition.

How long does galvanized paint last?

Generally galvanized paint applied by cold galvanizing process protects the metal for 8-10 months as it is just a coating without any chemical bonding with the surface to prevent it from rust.

But it also depends upon the surrounding atmosphere. The protection duration will be less if the metal is exposed to salty atmosphere which is generally near coastal areas.

How can the coating “Repair” itself?

Initially, the protection provided by SZS No Rust Zinc is wholly that of anodic action.As the zinc is sacrificed, zinc hydroxy carbonates and other zinc salts form in the coating, making the coating denser and reducing its conductivity. Thus the anodic action continues until the coating is converted into a dense, impervious, cement like coating. The coating will now function as an impermeable barrier, resistant to weather, water and fume attack.

How much zinc do you get?

The most important anti-corrosive component in both galvanized and zinc rich paint coating is zinc. The mass of zinc present is the standard method of rating the durability of metallic coatings and all international standards use mass per square metre( or mass per square foot in the USA) to define coating durability for a wide range of galvanized products.

The amount of zinc in a zinc rich paint coating is not clearly defined and the method of specification is misleading. Zinc rich paint specifications nominate the percentage of zinc by weight, in the dry film of the paint coating.
Thus, inorganic ZRP may nominate 78% zinc in the dry film and a high quality organic(epoxy) ZRP may nominate more than 90% zinc in the dry film. Because zinc is approximately 7X as dense as the organic binder material, the volume of zinc in a ZRP coating is much less. The mass of zinc per square metre will thus be significantly lower than that of a galvanized coating of the same thickness. Tests done by South Australian Roads Authority in testing the zinc content of various types of zinc rich paint has found the following:

• Inorganic Zinc Rich Paint – 75 micron coating
• Solvent Based – 185g/m2
• Water Based – 280g/m2
  Organic Zinc Rich Paint – 75 micron coating
• Solvent Based – 185g/m2

Hot dip galvanized coating range from 450g/m2 on thinner steel sections, to well over 600g/m2 on heavier structural sections.