Sandblasting Tips: How to Avoid Flash Rusting

Posted on: 30 December 2019

If you're removing rust from your car's body with a wet sandblasting technique, then there is a risk that you'll create a new problem in the process. You could end up with flash rust on parts of your car after you remove the initial corrosion.

What is flash rusting and how can you prevent it?

What Is Flash Rust?

Flash rust is a kind of corrosion that sometimes develops on a car's body when you use water-based sandblasting methods. Even though your main aim here is to get rid of the original rust, you can create a new type in the process.

For example, if you use dustless blasting, then the abrasive blast material is mixed with water. This water, when it comes into contact with the metal you're working on, can create its own kind of rust.

This flash rust isn't the same as the corrosion you're trying to remove; it is a different problem. It can appear very quickly after the blasting process.  

Typically, a metal with this problem turns a rusty colour within hours or even minutes, in some cases. This usually happens because of a reaction if the water is left to dry on the metal or you don't coat the metal quickly after blasting. It can also happen if old rust particles stick to wet metal after it has been sandblasted.

Flash rusting is a new problem you need to deal with. Left alone, it causes problems on your metalwork. It can also affect the final paint finish you get.

How Can You Prevent Flash Rust?

The easiest way to prevent flash rust after sandblasting is to use a rust inhibitor. This is a short-term solution that protects your bodywork so that you have time to finish the job.

For example, an inhibitor slows down the oxidation process, provides a temporary protective coating and blocks oxygen from coming into contact with the metal. This should keep flash rust off your car.

An inhibitor usually goes on in two stages during sandblasting. It is often added to the water in the blasting mix itself. The area that is blasted is then rinsed down with the inhibitor to clean away particles and create a protective coating.

To find out more about flash rust and how to prevent it, talk to your auto body shop. Their sandblasting professionals can explain the best way to get rust off your car without causing further problems.