NanoPrime and Chlorides Printable File

CHLORIDES & NANOPRIME

Especially in ocean, offshore and coastal environments where the atmosphere contains a higher percentage of chlorides, it is almost impossible to eliminate the presence of chloride molecules on freshly blasted or prepared metal surfaces.

CHLORIDES (salt) & COATINGS – WHY TYPICAL COATINGS FAIL ON PREPARED METAL SURFACES

Even the smallest particles of chloride on a blasted steel surface prior to coating with a primer can eventually lead to a coating system’s failure. Chlorides are highly hygroscopic, meaning they absorb moisture from the air. Applying primer coating to a surface that has chloride molecules present will trap the chlorides and moisture against the substrate. This will eventually cause corrosion spots under the primer coating.

Sand or grit blasting makes steel very reactive and even if a typical alkaline primer coating is immediately applied, it is nearly impossible to not have some amount of chlorides trapped.

Chloride ions on the substrate surface will break down the passive oxide layers of metal particularly with steel and aluminum. This will lead to pitting corrosion that can cause structural failure and not just to the paint system.

Some conventional primers, especially zinc rich epoxy primers, can be chemically degraded by chlorides and that disrupts the cross-linking action during the curing process of those primer coatings.

CHLORIDES (salt) & COATINGS – WHY TYPICAL COATINGS FAIL WITH CHLORIDES ON THE SURFACE

Residual soluble chlorides or salts on a coated steel surface can accelerate corrosion when due osmotic blistering occurs. This happens when moisture diffuses through the coating film via osmosis and dissolves water-soluble salts that are entrapped. Those entrapped salts are hygroscopic and the moisture pulled in creates concentrated pressure under the film that exceeds the adhesive strength of the coating and breaks through the surface. This then exposes the metal underneath and accelerated corrosion in the exposed area occurs.

CHLORIDES & COATING WARRANTIES

Practically all other primers are pH alkaline, and they do not react to passivate chlorides or salts. Therefore, chlorides that are in ocean, offshore and coastal environments are impossible to eliminate and will eventually lead to failure. This is the reason for strict specifications by coating manufacturers regarding chlorides and the warranty of the coatings.

THE NANOPRIME DIFFERENCE

The phosphoric acid in Nanoprime reacts with alkaline salts and passivates them. The means the sales become a non-reactive, neutral part of the coating. Additionally, the iron phosphate layer that is created when Nanoprime reacts with the substrate is impermeable and does not allow moisture or chemicals to penetrate to the substrate.

Even when the Nanoprime coating is damaged, the surrounding iron phosphate prevents corrosion from spreading. The iron phosphate and the remainder of the Nanoprime layer have a “diffusion zone” where the acrylic polymer matrix of Nanoprime and the iron phosphate are mixed. This mixture creates an integrated coating that is chemically bonded to the substrate and creates excellent adhesion and corrosion protection. The neutralization of the chlorides and the layer of iron phosphate that is bonded to the substrate eliminates any chance of corrosion under the film of coating.

All said, Nanoprime is unique in its ability to protect against the corrosive effects of chlorides.