First of all, Thanks for your help on solving in any issue for this project at MCS Steel, From the beginning, Totani_San (Resigned) who was in charged for this project, he had contacted with MCS previously (not me and did not sent me the painting procedure) by having to specify painting system for 1st coat: SD Zinc 500 = 50 microns and 2nd coat: Esco NB (Light gray) = 100 microns, he designed surface preparation was to be St3 ( Power Tools Cleaning ) which it is not corrected because SD Zinc 500 is Epoxy Zinc Rich ( Zinc Powder 80% content ), It will cause paint film peeling off that come from poor surface preparation process., which I do not agreed in this recommended from him. So I must have informed to MCS Vice President (Mr.Pronchai) / R&D Mgr.(Mr.Kakuta) for making the correct method of surface preparation by abrasive blast cleaning ISO 8504 (Sa2.5) before painting with Zinc Rich Primer., which MCS-Steel, have agreed with us without confuse and clear in surface preparation method.
You can see the referred report from Naka2 Photo-report of St3 not good enough, Yesterday.
Overnight, It has rust occurred on steel surface under coated of SD Zinc 500