Surface Preparation Guide

The quality of surface preparation, and surface repair on new, or repainted surfaces, significantly affects the amount of preparatory work that will be required for all subsequent repaints. Surface preparation and surface repair are the more important requirements for maximum durability from any paint system.  Because the result of surface preparation and repair are quickly concealed by the 1^st coat of paint, the effects are not usually evident until the premature paint failure occurs.

Surface Preparation Standards Include:-

White Metal Blasting (Sa 3, SSPC-SP5, NACE No 1)

A surface with a grey-white, uniform metallic colour, roughened to form a suitable anchor profile for coatings.  The surface is free from all oil, grease, dire, mill scale, rust, corrosion products, oxides, paint and other foreign matters.

 

 

Near White Metal Blasting (Sa 2.5, SSPC-SP10, NACE No2)

A surface from which all oil, grease, dirt, mill scale, rust, corrosion products, oxides, paint or other foreign matter have been removed except for light shadows, streaks or other discolorations (of oxide bonded to metal).  At least 95% of any given square inch has the appearance of “White metal”, and the remainder is limited to slight discolouration.

 

Commercial Blast Cleaning (Sa 2, SSPC-SP6, NACE No3)

A surface from which all oil, grease, dirt, rust scale and foreign matter have been removed except slight shadows, streaks or discolouration caused by rust stain or mill scale oxide binder. At least 2/3 of any square inch shall be free from all visible residues and the remainder shall be limited to light discolouration, slight staining, or light residues mentioned above.  If the surface is pitted, slight residues of rust or paint are found in the bottoms of the pits.

Brush Off Blast Cleaning (Sa1, SSPC-SP7, NACE No4)

A surface from which oil, grease, dirt, loose rust scale, loose mill scale and loose paint are removed, but tightly adhering mill scale, rust, paint and coatings are permitted to remain if they have been exposed to the abrasive blast pattern, so that numerous flecks of the underlying metal are uniformly distributed over the entire surface.

 

Hand Tool Cleaning (SSPC-SP2)

Power Tool Cleaning (SSPC-SP3)

Solvent Cleaning (SSPC-SP1)

These specifications describe methods of preparing metal surfaces by removing loose mill scale, loose rust and loose paint by wire brushing, sanding, scraping or chipping with power tools or solvent cleaning.