Selected Answers

From jesse chasteen of schriener construction on August 18, 2011:
     ISO 8502-3 procedure will ...read more      ISO 8502-3 procedure will give you the steps for surface cleanliness prior to coating of steel substrates.It is commonly called the Tape Test.

From dwie hermanto of IPI on August 12, 2011:
     I thinks the best first s ...read more      I thinks the best first step should be SSPC-SP 1 and high-pressure, fresh water or steam to remove all contamination. Then the surface shouild be abraded, followed by  fresh water wash or steam and finally check chloride levels. If they are acceptable, proceed to painting.

From vikraman govindraj of Rigmetals L.L.C on August 13, 2011:
     From my knowledge, stainl ...read more      From my knowledge, stainless steel is not blasted. It will be pickled and passivated. Passivation with chromic or phosphoric acid will form a thin adhesive layer for paint to adhere.

From R.K. Singh of Chemdale Coatings Pvt Ltd on November 2, 2011:
Blasting stainless steel should be avoided. C ...read more Blasting stainless steel should be avoided. Cleaning with chloride-free solvents, pickling, and passivation with chromic or phosphoric acid will form a thin adhesive layer for paint to adhere.

From Lee Edelman of Independant on August 10, 2011:
     Before abrasive blasting, ...read more      Before abrasive blasting, you should do SSPC-SP 1, Solvent Cleaning, to remove any grease or oil, followed by chloride removal by means of 5K pressure wash, utilizing scrub brushes if needed. Check to ensure chloride levels are within specified range. After abrasive blasting, you can check the cleanliness by means of tape and 30x magnification.

From Sukhmander Singh of Serv Consult on August 18, 2011:
     In my experience, garnet ...read more      In my experience, garnet blasting can leave dust on a stainless steel surface, especially if the quality of the garnet  is poor. I am interested to know how this dust is to be removed and how to check that the surface is free from dust before painting. Will use of stainless steel shots or grit overcome this problem?

From Trevor Neale of Blastech Corporation on August 11, 2011:
     I submit that the current ...read more      I submit that the current SSPC surface preparations specifications do not adequately address preparing stainless steel. Following the esential thorough cleaning, the blast media and profile should be specified in detail. Generally, it is preferable to use only extremely hard mineral abrasives such as aluminium oxide or garnet of suitable particle size to achieve the required profile and density for the coating system being applied.

From David Lemke of Team Industries on August 17, 2011:
     Since we are discussing o ...read more      Since we are discussing only about a stainless steel substrate, then I will only refer to that portion of SSPC-SP 16, which is Brush-Off Blast Cleaning of Coated and Uncoated Galvanized Steel, Stainless Steels, and Non-Ferrous Metals. The stainless substrate should then be tested for chlorides first (if suspected or specification requires the testing) to determine the type of SSPC-SP 1 to preform. Solvent or alkaline cleaners are both covered in SP 1, but chlorinated solvents cannot be used for solvent cleaning on stainless steel. Also, solvents won't remove any chloride residues if present. Once the substrate is cleaned and rinsed, if detegents were used, then the substrate to ready to be abrasive- blasted. SP-16 does not cover what type of material the abrasive media has to be, but if something is made of stainless steel, I sure wouldn't think you would want to use steel grit. We have used garnet, which seems to be the preferred choice, but aluminum oxide, glass beads, or stainless steel grit  can also be considered. And, if the possiblity of having carbon steel residue deposits embedded in your stainless steel isn't an issue, you could use steel grit. SSPC-SP16 does state that a minimum profile of 0.75 mil has to be achieved. After the removal of the dust from blasting, you could do an ISO 8502-3 Dust Assessment to determine the cleanliness of the substrate. It is 10x magnification that is associated with ISO 8502-3, but by the same token, the SSPC abrasive specifications calls for the surface to be free of contaminants without the use of magnification. So do the tape test, and if you cannot see debris without out magnification, it should be ready to coat.