GUIDELINES FOR FIELD APPLICATION OF INORGANIC ZINC RICH COATINGS

Scope

This application instructions cover the surface preparation, application equipments and application details of In-organic Zinc Rich Primer.

Surface Preparation Application Mixing of Paints Drying and Curing Film Thickness Special Instructions

A. Surface Preparation

Remove oil, grease and other contamination within a suitable detergent followed by high pressure water washing. Aromatic solvents can also be used to remove the contaminants.

For welds and other heat affected areas, prior to above treatment, ensure that all welds are complete and continuous without cracks and pinholes. Sharp edge must be removed or rounded off. Soap traces/alkali deposits on weld joints used for pressure testing must be removed by fresh water washing and scrubbing with stiff nylon brushes. Remove all weld spatters.

After above operation, grit blast to Sa 2 ½ of Swedish specification. For severe exposure conditions, girt blasting to Sa 3 is suggested for optimum results. The surface profile after blast cleaning shall be 50-75 microns.

Note: Use steel grits, Aluminium oxide grits or similar sharp edged abrasives free of foreign motlers. The compressed air must be clean and dry. The steel grit with particle size of 0.2-1.0 mm or Aluminium Oxide of 0.4-1.8 mm should generally help to achieve the above surface profile when the air pressure at nozzle is about 100 psi.

B. Application

Inorganic Zinc Rich Primer can be applied by conventional spray equipment, airless spray equipment & brush (only for touch up).

	Conventional spray equipment
	Inlet Pressure–20–40 psi
	Nozzle Orifice-1.8-2.2 mm
	Pressure pot must be fitted with an air driven agitator to maintain continuous mixing

Only specified thinner as per data sheet shall be used for thinning and cleaning the spray equipment. For thinning and cleaning the spray equipment. For thinning upto 25% thinner as specified in the data sheet shall be used. Apart from correct spray technique, the amount of thinner shall be adjusted in such a way that the coating applied is wet and smooth just after application. Since the primer has fast drying character, the measurement of wet film thickness shall be used as tool for rough assessment in controlling the deposition of the coating.

	Airless spray equipment –0.019-0.025 inches
	Nozzle Pressure-1400-2100 p.s.i.

The amount of thinner necessary will depend upon prevailing conditions such as temperature, humidity, wind flow, ventilation, etc. Select small nozzles for spray application of complicated and non-regular structures.

C. Mixing of Paints

Use phenolic lacquered containers of plastic buckets for mixing. Avoid part mixing of the paint. Before mixing, stir/shake the hydrolysate part thoroughly. The powder portion should be added to the hydrolysate component slowly with constant mechanical stirring. Continue stirring until the mixed paint is free from lumps. Filter the mixture through wire screen of 30-60 mesh. Keep the mixture continuously stirred during application and ensure that it is utilised within 3 hours.

D. Drying and Curing

Inorganic Zinc Rich Primer are sensitive to environmental conditions for drying and curing. This product requires minimum RH of 50% and steel temperature of minimum 10°C. In case skin temperature of steel is more than 40°C spraying shall be done by extra thinning to avoid dry spray application.

The curing may be promoted at low humidity by spraying fresh water after 4-6 hrs of application of primer and keeping the surface constantly wet until curing is complete.

The complete curing can be checked by rubbing the coating with a cotton soaked in thinner. If the coating remains unaffected, the curing is complete.

The full hardness and curing will be obtained after weathering of Zinc Rich Primers.

E. Film Thickness

In case of long term protection without topcoats of DFT of primer shall be 75 microns. However with topcoats 50 microns DFT is acceptable.

Note: Ensure proper film thickness of weld seams, edges and corners.

There is always a risk of Muderacking/peeling with Inorganic Zinc Rich DFT exceeding 125 microns, in this case it requires total upgradation by reblasting.

F. Special Instructions

	Excessive film build-up than recommended DFT may lead to mud cracking. In such case the coating has to be reblasted.
	Application of second coat over first coat should be avoided.
	Product should not be applied on surfaces unless blast cleaned to min Sa 2 ½.
	Painted structures should be kept atleast 4 inches above ground.
	Use suitable sealer/tie coat over the primer in case of projects where the finish paint application is generally done after erecting the structures.
	Good ventilation is essential in confined areas. Painters should wear adequate personal protective equipments e.g. air fed mask, safety glasses, etc.
	Keep away the material from open flame and sparks. Protect Zinc dust against moisture.
	Please refer to our safety data sheet.