Dry the surface immediately after you rinse the RustBlast off, and you will minimize flash rust. A light film of flash rust is normal when water hits bare metal and it does not affect the KBS 3 Step Rust Prevention or Tank Sealing System, so if all you have is light surface rust, move on to the next step.
Why Flash Rust Happens At All
RustBlast is water based, and the last step of using it is a thorough water rinse. Water plus freshly stripped bare steel plus air equals oxidation, and it can start within minutes. That is flash rust. It is a cosmetic surface film, not the pitted structural rust you just removed, and it forms on top of the zinc phosphate layer RustBlast leaves behind.
The RustBlast directions call for rinsing thoroughly with water after treatment and then allowing the surface to dry completely. How fast you get it dry is the whole variable.
How to Keep Flash Rust to a Minimum
- Rinse thoroughly, then dry the surface right away rather than letting it air dry slowly.
- Use compressed air, clean lint free rags, or a heat source to pull the water off fast.
- Work in warmer conditions when you can. RustBlast is more effective when the surface and ambient temperature are warmer, and warm metal dries faster.
- Do one section at a time on a large part so no area sits wet while you work elsewhere.
Ideal working temperature for RustBlast is 55 to 90 degrees F.
What to Do If You Already Have Flash Rust
If it is light surface rust, proceed to the next step. RustSeal is designed to be applied directly over rust and forms a non porous shell over it, so a thin flash film is not a defect you have to chase. Heavy new rust is a different matter: if the part sat wet long enough to build real scale, re treat it with RustBlast.
The White Powder Is Not Rust
Once dry, RustBlast leaves a slight white powdery residue. That is zinc phosphate, and it is there on purpose because it aids adhesion of coatings such as RustSeal. Do not scrub it off. It is easy to mistake for a problem on a part that also has a little flash rust, so check the color: zinc phosphate is white or pale gray, flash rust is orange.
Frequently Asked Questions: RustBlast and Flash Rust
Still have questions about flash rust after RustBlast? Contact us for help.
