Surface Preparation For Zinga

Surface prepared for Zinga application. Blasted to SA 2.5 cleanliness.

Photo of steel which has been blasted clean to SA 2.5 cleanliness

As with most protective coatings and paints, the surface preparation for Zinga is key. It cannot be stressed strongly enough that the key to Zinga’s long life is in the thorough preparation of the steel substrate to the correct specification. Please always follow the appropriate Zinga UK specification in conjunction with the relevant Technical Data Sheets. (TDS)

ZINGA can be applied on a slightly rusted surface, but due to the barrier of rust between ZINGA and steel, the galvanic protection is affected and therefore the performance of ZINGA is reduced.

Since ZINGA can offer a sustainable, long lasting protection of steel surfaces, it is profitable to invest in a thorough surface preparation which prevents premature failure of the coating.

The following information will give a general guide to the coating and its application.

Marine structures

  • Remove all crustacean growth using either a UHP waterjet or a high-pressure washdown
  • Dry off
  • Blast-clean to SA 2.5 cleanliness

Old or worn galvanising, thermally sprayed zinc (TSZ) or old Zinga

  • Steam clean to remove all contamination from porous surfaces
  • Dry off
  • Blast clean as normal

New steel

  • Steam-clean or high-pressure wash-down all surfaces
  • Allow to dry
  • Blast-clean to a cleanliness standard of SA 2.5

New galvanised steel

  • Steam-clean
  • Sweep-blast the surface(s) at a blast-pressure of 55 psi using a 45o nozzle angle to avoid – Removing any existing zinc thickness.

Cast-iron

  • Steam-clean or high-pressure wash-down
  • Allow to dry
  • Blast-clean to SA 2.5 cleanliness

Aluminium alloys

  • Solvent clean as per SSPC-SP1 Standard
  • Blast-clean with aluminium-oxide media grade 3
  • Vacuum surface(s) before paint application

Note 1: The term “high pressure” means a minimum water-pressure of 10,000psi. Any pressures below this level will not totally remove engrained chlorides.

Note 2: The grit used on all structural steelwork must comply with 50µm and 80µm depending on the type of application). The chosen grit should always be able to achieve a blast roughness of 12.5 to 15 microns. It should be noted that UHP Blasting does not create a profile and should therefore never be used as the sole means of surface preparation. UHPAB is an excellent form of blast-cleaning for marine structures as it removes all crustacean growth, scale, engrained chlorides and invisible contaminants.

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