-7-6.SELECTING THE PROPER SURFACE PREPARATION GRADESurface preparation is a very important factor affecting the durability of paint film.Fig. 5 shows the results of a coastal weathering test which was done with different dry film thicknesses of catalized epoxy paint on surfaces treated by power-tool cleaning (SSPC SP 3) and blast cleaning (SSPC SP 10).We see that the high-grade surface preparation results in long-term durability. Poor surface preparation does not provide long-term durability.Judging from the test results, we may conclude that coating should be planned so that the surface preparation should be of the highest grade possible.Remarks1. The surface was scratched along the right side prior to weathering.2. The weathering test was continued for 5 years along Chiba seacoast in Japan.Grade of surfacepreparationPower Tool Cleaning (SSPC SP3) Blast Cleaning (SSPC SP 10)Dry film thicknessof epoxy paint200μ300μ100μ200μ300μ100μBadResultRusting atnon-scratched area FairFairFairExcellentExcellentFig. 5 Coastal Weathering Test Results with Catalized Epoxy Paint