As seen in Photo 5, the salts are concentrated at the corroded areas. Note that in and around the pitted areas the salts have formed an electrochemical attachment to the steel that abrasive blasting did not remove. Had the surface been coated immediately after abrasive blasting, those salts would now be beneath the coating and the mechanism for a premature failure would already be underway. NOTE: This photograph also shows how testing performed at a specific location can offer differing results from another test at a very near proximity. Each test performed is specific to the locale being tested. It is also evident in the same photograph why it is recommended to perform testing at pitted locations rather than at a flat non-corroded location.
As seen in Photo 3, the salts are now not only concentrated in and around the pitted locations, but the addition of the pressure wash with tap water has not removed them and has actually caused them to spread over a larger area of the surface. Again, had this surface been coated immediately after washing, the corrosion mechanism would be in place and underway.
Photo 4 shows that the addition of the soluble salt remover has actually removed the salt, as evidenced by the lack of a corrosion reaction. What is also visible is the “operator error”. The operator who washed this panel did not wash 100% of the surface adequately, but even with that operator error, the minimal rust back indicates that there are only minor amounts of salt left, as evidenced by the very slight corrosion reaction after 24 hours. Were this panel coated immediately after washing, the ultimate coating performance would be far more successful than either of the other two samples.
Many specifiers are very aware of just how detrimental soluble salts are, while others simply have not yet learned. Hopefully, this visible evidence will help them understand the need to address non-visible requirements in specifications.