Solved: The Mystery of the Reappearing Mold Rust

“It just kept happening.

“We would clean, polish and apply rust preventive to the mold. Then the next day while molding we would see rust forming. Then we would again clean, polish and apply rust preventive for overnight protection. Next day, same issue.

“This just kept happening no matter how often we cleaned and removed any hint of rust. Needless to say, I gotta get this resolved so I don’t keep wasting my time and get my boss out of my workshop.”

The boss is hovering...

OK, now no one wants their boss asking everyday “why is the mold still rusting?” or “what is going on that this keeps happening,” which all really means “you gotta figure this out, now!”

No detail is too small...

So, we started by reviewing all of Rod’s (not his real name) maintenance procedures. We asked him to tell us exactly what he was doing, step by step. Everything sounded right.

Then we asked about the environment, like maybe he was molding with PVC or some other resin that could create acidic gas. Nope, that wasn’t it either.

What about the cleaner, polish and rust preventive being used? It was all good stuff that should do the job.

Since we were not on site, we could not see exactly what was happening. But if it is not the resins or environment, nor bad aerosols, what was left?

What if...

What if, after cleaning and polishing, the rust preventive wasn’t applied as completely as Rod thought (sorry Rod)? Spraying a rust preventive back and forth, up and down over a big mold surface, if not done carefully, could leave some areas unprotected.

We suggested using a rust preventive with a colored dye. Unlike clear rust preventives where you try to see if every surface is “wet,” a rust preventive with a colored dye makes it real easy to see coverage. So, we sent a free sample of Quick RP rust preventive with red indicator dye.

Yep, that was the answer. Rod was not getting complete coverage. Now he sees what he missed and he doesn’t see his boss in the shop as much.

Mystery solved.

Learn more about mold releases, cleaners and rust preventives