Field Applied Thermoplastics — Ready For Primetime?

Magnified view of better application of pool 1: Material is flat and has the appearance of fish-scales.

 

Magnification of rusting areas. Likely due to applicator standing too far back from substrate, leading to the plastic globules not being sufficiently molten upon impact. Instead of the plastic flattening on impact, like a pancake, they remained more drop-like.

In the case of the rusting pool, we are unaware of the exact thermoplastic polymer material used, but the specifics don’t matter.

What matters is that the technology is here. But is it ready for prime time?

Thermoplastic materials are exceedingly well understood. Years ago, we lined the interior of large silos containing thermoplastic beads — polystyrene — used for injection molding. (Picture the ubiquitous college red Solo cup)

The problem in field application is that you have to inject your powder or otherwise chopped up plastic into a flame — and use air to “spit” it onto the substrate. And using live flame on a thermoplastic changes the material due to the inconsistent heating and infusion of oxides and other contaminants from combustion into the thermoplastic.

It’s a complicated stew of flame, heat, plastic, compressed air and technical skill. In the case of the swimming pool, you can see in Photo 1 that the surface of the thermoplastic is relatively smooth, and you can see the individual “splatters” of the plastic material having been deposited onto the substrate, and built up onto itself, like dripping wax from a candle onto a piece of paper over and over again.

Chicago Corrosion Group staff inspecting/testing the first tack-coat of thermoplastic material. An existing epoxy system had to be completely removed prior to application. CCG tested surface prep, DFT, holidays and visually for appearance and density.

In Photo 2, where there are rust spots and what appear to be holidays, you can see that the material is more spherical in nature, likely due to the applicator being too far away from the substrate, and allowing the plastic to cool too much, and starting to harden on its way to the substrate. So instead of melting onto the surface like candle wax, it splattered, more like gum.

I’m not prepared to say that this is revolutionary, but it’s close. In my humble opinion, it’s the most profound jump in corrosion mitigation technology and beautification materials I’ve seen in years. It has potential application for bridges, exterior structural steel and, even, potentially, internal tank lining.

Spray application of thermosetting material.

We are working with a local contractor in trying to understand and develop the technology for further field applications. If you’re interested, give us a shout.

Warren Brand’s coatings career has ranged from entry-level field painting to the presidency of two successful companies. Over nearly three decades, he has project-managed thousands of coating installations and developed specs for thousands of paint and coating applications. NACE Level-3 and SSPC PCS 2 certified, Brand, an MBA and martial-arts instructor, now heads Chicago Corrosion Group, a coatings consultancy.

Close-up view of second coat. Material is flat and exhibits the fish-scale type of pattern. This was prior to the final application, which deposits additional material, and which also heats up the system and substrate to create a monolithic, cohesive system.Close-up view of second coat. Material is flat and exhibits the fish-scale type of pattern. This was prior to the final application, which deposits additional material, and which also heats up the system and substrate to create a monolithic, cohesive system.