A mastic waterborne acrylic built for overcoating rusted steel is the newest product from high-performance protective coatings manufacturer Tnemec Company Inc. (Kansas City, MO).

Series 118 Uni-Bond Mastic is described as a single-component, mastic waterborne acrylic coating designed for use on minimally prepared sound rusted steel and previously coated surfaces in a range of environments.

Tnemec Company Inc.

In Cortland, IL, Series 118 was specified for the exterior of an elevated municipal water storage tank where a limited budget prevented the owner from abrasive blasting exterior steel. After a severe winter of freeze-thaw conditions, the coating system maintained its original appearance, the company claims.

The rust-inhibitive tie coat can be used with acrylic and solvent-borne urethane and fluoropolymer finish coats, according to Cory Brown, vice president of technical services.

“With Series 118, it is possible to apply six to eight mils dry film thickness (DFT) per coat,” Brown explains. “Although it offers a fairly high standing viscosity, Series 118 sprays on easily with dry-fall characteristics that reduce the potential for overspray issues on buildings and surrounding property.”

The new product has been specified as an overcoat for steel water tanks, vessels and other industrial and architectural metal substrates, the company says.

Surface preparation consists of power washing steel at 5,000 psi and some mechanical hand or power tool cleaning to remove loose rust, scale and deteriorated coatings to obtain a sound surface for coating, it adds.

The coating reportedly delivers strong adhesion properties, as well as excellent flexibility and impact resistance.

“The coating has excellent elongation, enabling it to expand and contract with the substrate as the temperature varies,” Brown adds.

More information: www.tnemec.com/.