CARC coatings:
military-grade polyurethane
for extreme environments

Why the military needed a new kind of coating

Before CARC, U.S. military vehicles were finished with alkyd-based paints — the same general chemistry used in commercial industrial coatings of the era. Alkyd coatings performed adequately for corrosion protection and camouflage, but they had a critical vulnerability: when chemical warfare agents such as nerve agents or blister agents contacted the coating surface, the porous alkyd film absorbed them. Decontamination with available agents — DS2 (diethylenetriamine-based solvent) and STB (supertropical bleach, a calcium hypochlorite slurry) — was only partially effective because absorbed agent could off-gas for hours after surface decontamination appeared complete. The coating itself had become part of the contamination problem.

The U.S. Army Materials Technology Laboratory developed CARC in the 1970s specifically to solve this problem. The solution was aliphatic polyurethane — a polymer system whose dense, tightly cross-linked structure resists both the absorption of organophosphate and organohalide chemical agents and the pH extremes of DS2 and STB decontaminants. A properly applied CARC topcoat allows chemical agents to bead on the surface and run off, and withstands repeated decontamination cycles without degrading.

CARC entered U.S. Army service in the early 1980s and has been the mandatory coating system for U.S. military ground vehicles and equipment ever since. Allied nations operate parallel specifications under NATO agreements, and CARC-equivalent systems are standard across most modern military forces.

Why aliphatic polyurethane: the chemistry behind CARC

The choice of aliphatic polyurethane as the CARC binder was not arbitrary — it reflects specific chemical properties that make it uniquely suited to the CARC performance requirements.

Chemical agent resistance

Chemical warfare agents such as VX, GB (Sarin), and HD (mustard) are typically organophosphate or organohalide compounds — polar molecules with some affinity for organic polymer matrices. Aliphatic polyurethane, when fully cross-linked, forms a polymer network of sufficiently high density that it presents a significant diffusion barrier to these molecules. The low surface energy of the cured CARC topcoat — achieved partly through the aliphatic structure and partly through specialized low-surface-energy additives — causes liquid agents to bead rather than wet the surface, slowing absorption kinetics.

Epoxy, alkyd, and aromatic polyurethane coatings all show significantly higher agent absorption rates than aliphatic polyurethane under the same exposure conditions — which is why they were unsuitable as CARC topcoats despite their other useful properties.

Decontaminant resistance

DS2 decontaminant is a highly alkaline, solvent-containing mixture (diethylenetriamine, ethylene glycol monomethyl ether, and sodium hydroxide) that attacks most organic polymers aggressively. STB is a strong oxidizer. A CARC topcoat must withstand multiple applications of both agents without blistering, adhesion loss, or significant degradation of the film. The aliphatic urethane linkage is substantially more resistant to alkaline hydrolysis than the ester linkage in polyester or the ether linkage in many other polymer systems.

UV stability

The "aliphatic" designation — referring to the absence of aromatic rings in the isocyanate component — is also what gives CARC its UV stability. Aromatic polyurethanes yellow and chalk rapidly in outdoor UV exposure because aromatic rings absorb UV energy and undergo photo-oxidation. Aliphatic isocyanates (HDI, IPDI, H12MDI) do not contain aromatic rings and are largely transparent to UV radiation, giving aliphatic polyurethane coatings excellent color and gloss retention in outdoor service.

IR signature management

CARC coatings do significantly more than resist chemical agents — they are active components of the vehicle's signature management system. Modern battlefield sensors include image-intensification night vision devices (which amplify near-infrared reflected light) and thermal imaging systems (which detect long-wave infrared emitted as heat). A vehicle coated in a CARC color with incorrect NIR reflectance stands out as an obvious target against natural terrain backgrounds, regardless of how well the color matches visually.

CARC pigment systems are formulated to match the NIR reflectance of natural terrain features in the relevant theater of operations. Green 383, for example, is formulated to match the NIR reflectance of deciduous vegetation (high NIR reflectance, roughly 40–60% at 800 nm). Tan 686A is formulated to match arid terrain. The NIR reflectance values are mandatory performance parameters in the CARC specifications and are tested per ASTM E1331.

CARC colors and the FED-STD-595 system

CARC topcoats are specified by FED-STD-595 color number — a U.S. federal color standard that defines colors by spectrophotometric measurement rather than visual chip matching. The most common tactical CARC colors used by U.S. forces are:

Camouflage patterns — MERDC, CARC 3-color, and others — are applied by stenciling or masking successive CARC colors over a base coat. Pattern specifications are defined by equipment type and theater of operations. All colors in a camouflage pattern must be CARC-specified to maintain IR signature compliance across the full vehicle surface.

The CARC coating system

Like all industrial protective coating systems, CARC performance depends on the full coating stack — not just the topcoat. MIL-DTL-53072 defines the complete system from surface preparation through topcoat application.

Applying CARC: process and requirements

CARC application follows a strictly controlled process defined in MIL-DTL-53072. Deviations from the specified process can compromise both the chemical resistance performance and the IR signature compliance of the finished system.

CARC vs. standard industrial polyurethane

CARC coatings are aliphatic polyurethane — the same broad chemistry used in commercial marine topcoats, aerospace finishes, and high-performance industrial coatings. Understanding what differentiates CARC from a standard commercial aliphatic PU topcoat is important for both specifiers and applicators.

The most important distinction is that CARC is a specified system — every material used must be from the Qualified Products List (QPL) maintained by the relevant military authority, and every application parameter is governed by MIL-DTL-53072. A commercial aliphatic polyurethane topcoat, however technically excellent, cannot be substituted for a QPL-listed CARC product on military equipment.