Steel - The surface should be blast cleaned to SSPC-SP 10-63T or NACE No. 2 i.e. loose rust and scales, dirt, grease, oil, paint, wax, weak oxide films and other contaminants should be removed. Blast cleaning to SSPC-SP 5-63 or NACE No. 1 is recommended where heavy corrosive conditions exist. That means a surface with a grey metallic colour, slightly roughened to form a suitable anchor pattern for coatings. This surface is free of all oil, grease, dirt, mill scale, rust, corrosion products, oxides, paint and other foreign matter. Hand or mechanical cleaning is not much effective.
Priming:
It is recommended that priming should be carried out within 4 hours if inside a building, but if exposed to weather, the steel must be coated immediately after blasting. Should it become necessary to leave cleaned surfaces unpainted overnight, such surfaces must be re-cleaned before painting. Paint only on dry surfaces. Do not paint exterior surfaces in damp weather or when the temperature is less than 10° C. The dry film thickness (DFT) should not be less than the DFT specified. Should the required DFT is not achieved in one coat, additional coats shall be applied until the minimum requirements are met. When the additional coats are applied, the re-coat time must strictly be followed. It is recommended that one coat of Blastprime EZP 200 at 25 microns minimum DFT should be applied on shot blasted steel whereas one coat at 50 microns DFT is required for grit blasted steel for best protection. All subsequent welds, burnt and cut edges, must be cleaned and priming coat be renewed where steel is primed prior to fabrication. More coats can be applied as per requirements.
Overcoating:
In common with epoxy coatings generally, overcoating should be carried out within 24-48 hours or left for 7 days when the coating has cured completely. However, Blastprime EZP 200 can be overcoated with conventional paints after 12 hours and with two-component systems after 24 hours. Care must be taken while overcoating the primed surface. Oil, grease, dirt etc. should be removed by degreasing the surface with degreasing solvents like tri-chloroethylene or xylene and subsequently washed off with fresh water. The surface should be allowed to dry before painting. |
