Because there is usually moisture in the air, it is quite common for a metal surface to flash rust after being rinsed with water. RustBlast is formulated to leave behind a dusting of zinc phosphate. The zinc phosphate aids in the adhesion of Tank Sealer. Zinc phosphate is white in color.
So, when the tank is rinsed after the RustBlast step, there is the dusting of white zinc phosphate that is left on the surface and that mixes with the brown surface rust. This often makes the appearance of the surface rust appear much worse because most of what is seen is the dusting of zinc phosphate.
If what you have is a dusting on the surface and the tank is bone dry, you care good to proceed to the Tank Sealer step.
TIP: You can always minimize the amount of surface rust by drying the tank immediately and quickly after the tank has been rinsed with water after the RustBlast step, but this is not necessary.
Please review the complete Tank Sealer Application Directions before beginning your project.