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40 OCTOBER 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 10 COATINGS & LININGS TABLE 1. SUMMARY OF CHLORIDE AND SULFATE ABRASIVE CONTENT AND TRANSFER Sack Chloride Sack Sulfate Top Bottom Top Bottom Abrasive #1 From abrasive (mg/kg) 1 2 33 38 Transfer (µg/cm 2 ) ND (A) ND 1 ND Plate surface after blast 0.058 mm (2.3 mil) profile; white metal — — — Abrasive #2 From abrasive (mg/kg) 5 5 1 1 Transfer (µg/cm 2 ) ND ND 1 ND Plate surface after blast 0.066 mm (2.6 mil) profile; white metal — — — Abrasive #3 From abrasive (mg/kg) 15 20 30 40 Transfer (µg/cm 2 ) ND ND 1 1 Plate surface after blast 0.058 mm (2.3 mil) profile; white metal — — — Abrasive #4 From abrasive (mg/kg) 1 ND 48 62 Transfer (µg/cm 2 ) ND 1 ND 1 Plate surface after blast 0.064 mm (2.5 mil) profile; white metal — — — Abrasive #5 From abrasive (mg/kg) 10 10 48 50 Transfer (µg/cm 2 ) ND 1 1 ND Plate surface after blast 0.061 mm (2.4 mil) profile; white metal — — — Abrasive #6 From abrasive (mg/kg) 10 10 ND 1 Transfer (µg/cm 2 ) ND ND ND 1 Plate surface after blast 0.076 mm (3.0 mil) profile; white metal — — — Abrasive #7 From abrasive (mg/kg) 10 10 ND 1 Transfer (µg/cm 2 ) ND ND ND 1 Plate surface after blast 0.071 mm (2.8 mil) profile; white metal — — — Abrasive #8 From abrasive (mg/kg) 1 ND 22 25 Transfer (µg/cm 2 ) ND ND ND 1 Plate surface after blast 0.066 mm (2.6 mil) profile; white metal — — — (A) ND: Nondetectable. Conclusions The following facts are summarized from the data collected: • Relative to transfer of soluble anionic species, the sulfate anion does not transfer as readily as chloride. This may be because soluble sulfate is more strongly adsorbed to the abra- sive particles than chloride. • The use of conductivity, based on the above, can lead to the rejection of usable material. Higher levels of solu- ble sulfate generate higher conduc- tivity yet do not demonstrate the same rate of transfer. • Variations in levels of soluble salts between samples would indicate a need for caution in abrasive selec- tion, especially for surfaces that will be subjected to critical service. • Th e w i d e vari ation in l e vel s ad- dressed in industry standards may not be taking into account the evolv- ing and more stringent limits to achieve the requirements of full life cycle coating performance, especially in critical or severe service. • A statistically significant data set developed from multiple blasted test panels could be used to generate cri- teria that meet the desired stringent requirements of surface cleanliness prior to coating. References 1 H.H. Uhlig, W.R. Revie, Corrosion and Corro- sion Control , 3rd ed. (New York, NY: John Wiley and Sons, Inc., 1985), pp. 74-78. 2 B.R. Appleman, "Painting Over Soluble Salts: A Perspective," JPCL 4, 10 (1987): p. 68. 3 B.R . Appleman, et al., "Effects of Surface C ont amin ant s on C o atin g L i fe ," S SP C / FHWA, SSPC 91-07, April 1992. 4 M. Morcillo, J. Simancas, "Effects of Soluble Salts on Coating Life in Atmospheric Ser- vice," JPCL 14, 9 (1997): p. 40. 5 M. Morcillo, F.J. Rodriguez, J.M. Bastides, "The Influence of Chlorides, Sulphates, and Nitrates at the Coating-Steel Interface on Underfilm Corrosion," Progress in Organic Coatings 31 (1997): pp. 245-253.