With the wars in Afghanistan and Iraq in full force, contracts from Tank-Automotive and Armaments Command (TACOM) are being awarded on a regular basis. The demand for chemical agent resistant coatings (CARC) and qualified applicators is at an all-time high. However, finishing professionals that want to participate in this market must adhere to strict specifications and guidelines. Complying with the requirements requires a basic understanding of CARC.

More than Just Camouflage Paint

Simply put, CARC is the coating requirement for tactical military equipment. CARC is much more than just camouflage paint; it is a complex and specialized "system" with some very unique characteristics. It entails the overall cleaning, pretreating, priming and top coating of a substrate. The system incorporates only approved products from a select number of approved manufacturers.

Finishing professionals who apply CARC should have a thorough working knowledge of the two main specifications pertinent to CARC: TT-C-490, which covers Cleaning and Pre-Treatments; and MIL-DTL-53072, which addresses Application Procedures and Quality Control. Designed to be used in conjunction with each other, these two specifications allow for a full understanding of the system.

As stated in section 3.1 of MIL-DTL-53072C:

"Application of the CARC system consists of four distinct steps, each of which is critical to the performance of the overall system: cleaning, pretreating, priming, and topcoating. The cleaning and pretreating procedures are standard methods required in any finishing process. When a wash primer pretreatment is used, drying/reaction must be complete when used under CARC. Otherwise adhesion and the CARC system may be adversely affected. The anticorrosive primers are epoxies, and the topcoats are polyurethanes for exterior surfaces and an epoxy for interior surfaces. All of the coatings in the CARC system are Qualified Products List (QPL) item; that is, there is a list of approved suppliers which must be used for product procurement. In addition, each batch of polyurethane topcoat must be checked by the specification preparing activity (SPA) for validation of the spectral reflectance (camouflage properties) and DS2 resistance. The local safety office, preventative medicine activity and local medical support facility must be consulted prior to initiating CARC application."

CARC Systems

The specific CARC system used depends on whether the substrate is ferrous or non-ferrous. Several coating options are available, with each supported by their respective specifications. By design, the coatings are compatible with each other. For example, MIL-P-53030 (primer coating, epoxy, water reducible) is compatible with MIL-DTL-53039 (formally MIL-C-53039: aliphatic polyurethane, solvent borne, single component top coat) (see Table 1). The Army Research Lab (ARL) has done a great job of addressing the many different coating environments by approving several different coatings, many of which are more environmentally friendly than systems of the past.

The pretreatments are designed to improve the adhesion of subsequent coatings and provide temporary resistance to corrosion. After cleaning, the pretreatments should be applied as soon as possible. There are five approved primer coatings, all of which are two-component epoxies that make up the corrosion resistance package. The three topcoats provide the color and the chemical agent resistance. The polyurethanes for exterior use provide the camouflage to visible and near-infrared detection. The epoxy is designed for interior use only and is a smooth, wear-resistant coating that can be easily cleaned.

The topcoats are designed to minimize the absorption of chemical agents and withstand a chemical wash during a decontamination process...thus the name CARC.

Other facets of CARC will be discussed in this column in future issues. With a basic understanding of CARC, finishing professionals can meet the needs of today's military.

Jon Pollina is in technical sales- military products at Hentzen Coatings, Inc., Milwaukee, WI. He can be reached at 414.353.4200 or jpollina@hentzen.com.