Sandblasting: What & Why?
The most vital part of any paint job, be it an industrial project with a high tech coatings specification, or a common drywall paint, is the surface preparation. Of course most jobs don't require sandblasting, but where there is metal present, it is strongly recommended.
Coatings performance is affected by proper product selection, application and surface preparation. Coating integrity and service life will be reduced because of improperly prepared surfaces. As high as 80% of all coatings failures can be directly attributed to inadequate surface preparation that affects coating adhesion. Selection and implementation of proper surface preparation ensures coating adhesion to the substrate and prolongs the sevice life of the coating system.
Below are samples of the four major types of sandblasting with a brief description of what they are. Keep in mind that these pictures are scans, and as such are not nearly as representative of the actual finished product as what we would like, but they'll do for these purposes.
White Metal Blast (SSPC-PC 5)
White metal blast cleaning is used when a totally cleaned surface is required. This method of cleaning is defined as a blast cleaned surface with a gray-white uniform metallic color. It shall be free of all oil, grease, dirt, mill scale, rust, corrosion products, oxides, paint, stains, streaks or any other contaminant across 100% of every square inch.
Near-White Blast Clng. (SSPC-SP10)
Near-white blast cleaning is defined as one from which all oil, grease, dirt, mill scale, rust, corrosion products, oxides, paint or any other contaminants have been completely removed from the surface. Very light shadows, very slight streaks or discolorations caused by rust stain, mill scale oxides or slight tight residues of paint or coating are permitted to remain.. Only 5% of every square inch may contain the slight discolorations mentioned above.
Commercial Blast Cleaning (SSPC-SP 6)
Commercial blast cleaned surface is defined as one in which all oil, grease, dirt, mill scale, rust and old paint have been completely removed from the blast cleaned surface, except that slight streaks, or discolorations caused by rust stain, mill scale oxides, or slight tightly adherent residues of paint of coating may remain. If the surface is pitted, slight residues of rust or paint may remain in the bottom of the pits. The slight discolorations mentioned above are limited to one-third of every square inch.
Brush-off Blast Cleaning (SSPC-SP 7)
Brush-off blast is defined as one in which all oil, grease, dirt, rust scale, loose mill scale, loose rust and loose paint or coatings are completely removed. Tight mill scale and tighly adherent rust and paint or coatings may remain as long as the entire surface has been exposed to abrasive blasting.
Since we at Randy's Professional Ptg. know and understand the value of sandblasting preparation, we have committed this company to the proper performance of such applications. We have many years experience in this field and will come to your project to assess and recommend which form of blasting will work for you.
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