Flash rust: the clock that starts the moment we finish

The moment steel is bare it starts oxidising. In humid conditions you can watch it happen — a light orange bloom across a surface that was bright grey twenty minutes ago.

Why wet blasting makes it a bigger issue

Wet blasting has real advantages: dust suppression and heat control chief among them. The trade-off is water on bare steel, which is exactly the condition flash rust needs.

What inhibitors do

We carry a rust inhibitor in the blast water. It leaves a thin protective film that holds the surface for a window — long enough to get a coating on, but not indefinitely. It is a schedule tool, not a permanent treatment.

An inhibitor buys you days, not weeks. Plan the blast around the painter, not the other way round.

Is light flash rust a problem?

It depends entirely on the coating system. Some tolerate a light bloom. Many high-performance systems specify a maximum permitted degree, and some require none at all. That is a datasheet question, and getting it wrong means re-blasting.

Practical sequencing

• Know who is coating and when before we start.
• On multi-day jobs, blast and coat in sections rather than stripping the whole asset first.
• Watch the weather. A humid stretch shortens every window.

The dry air across southeast Alberta buys a little more time than a coastal climate would, but not much, and not on a humid day in the Medicine Hat valley after rain. The clock still starts the moment the surface is bare.