MIL-PRF-22750: Epoxy Coating Standard for Military Equipment
MIL-PRF-22750 is a United States military performance specification covering two-component epoxy coatings used on metal, composite, and plastic surfaces. These coatings are applied to military equipment requiring long-term corrosion protection, chemical resistance, and durability under sustained environmental exposure.
The standard is managed by the Naval Air Systems Command (NAVAIR) and is used across the U.S. Army, Navy, and Air Force, as well as allied defence industries and defence contractors worldwide.
What Is MIL-PRF-22750?
MIL-PRF-22750 defines the performance requirements that an epoxy coating must meet to be approved for use on military and government equipment. It is not a single product but a qualification framework. Coatings that pass the required testing are listed on the Qualified Products List (QPL) maintained by the Department of Defense.
Only QPL-listed products can be specified in military contracts and government projects. Procurement teams should always verify that the specific MIL-PRF-22750 product they are using appears on the current QPL before application.
MIL-PRF-22750 coatings are two-component systems consisting of a resin base and a curing agent. When mixed and applied, they form a dense cross-linked film that resists chemicals, abrasion, and environmental degradation. They are typically applied over a qualified primer, most commonly one meeting MIL-PRF-23377 or MIL-DTL-53022, to maximise adhesion and corrosion resistance.
Key Performance Requirements
MIL-PRF-22750 coatings must meet specific mechanical, chemical, and environmental criteria. The table below summarises the most important performance requirements.
| Property | Requirement |
|---|---|
| Adhesion | Must remain intact under cross-cut or tape-pull tests after curing |
| Hardness | High pencil hardness after full cure, typically H or above |
| Chemical resistance | Must resist fuels, hydraulic fluids, lubricants, and cleaning solvents |
| Corrosion protection | No blistering or rust after 1,000-hour salt fog exposure |
| Flexibility | Must withstand 180-degree bend without cracking or delamination |
| Color stability | Must maintain color and gloss under UV and heat exposure |
| VOC limits | Formulations must comply with EPA and DoD environmental regulations |
Types and Classes
MIL-PRF-22750 defines types and classes to cover different application requirements and operational environments.
Types distinguish between standard formulations, low-VOC versions, and high-solids variants designed to meet environmental compliance requirements in restricted workspaces.
Classes determine color, finish, and infrared reflectance characteristics. Flat finishes are typically specified for tactical applications to reduce glare and visual signature. Gloss finishes are used where appearance and ease of cleaning are priorities.
Coatings can be applied by spray, brush, or roller and cure at ambient temperature or with mild heat. Once fully cured, the film provides a hard, chemical-resistant surface that can remain serviceable for decades under proper maintenance conditions.
MIL-PRF-22750 Touch Up and Repair
Touch up of MIL-PRF-22750 coated surfaces follows the same material requirements as the original application. The touch up area must be properly prepared, including cleaning and light abrasion of the surrounding coating to ensure adhesion at the repair boundary.
For field touch up, single-component or pre-measured touch up kits are available from QPL-listed manufacturers. These maintain compliance with the specification while allowing repair without full spray equipment. The touch up coating must match the original class and finish to maintain visual consistency and infrared reflectance properties.
MIL-PRF-22750 Technical Data Sheet and MSDS
Each QPL-listed MIL-PRF-22750 product comes with a technical data sheet (TDS) specifying mix ratios, pot life, application thickness, cure schedule, and compatible primers. The TDS should always be consulted before application as these parameters vary between manufacturers and formulation types.
Safety data sheets (SDS, formerly MSDS) are required for all MIL-PRF-22750 products and must be available at the point of use. These cover handling precautions, personal protective equipment requirements, and disposal procedures for both the mixed coating and individual components.
Comparison with Related Coating Standards
MIL-PRF-22750 is one of several military coating specifications. The choice between them depends on the substrate, the operational environment, and whether the coating is a primer, intermediate, or topcoat.
| Specification | Type | Typical Use |
|---|---|---|
| MIL-PRF-22750 | Two-component epoxy | High-durability intermediate or topcoat, excellent chemical resistance |
| MIL-DTL-53039 | Polyurethane | Exterior topcoat with UV resistance and flexibility |
| MIL-PRF-23377 | Epoxy primer | Corrosion-resistant primer applied under topcoats |
| MIL-PRF-85285 | Polyurethane | Aircraft and vehicle topcoat, good weathering performance |
In many coating systems, MIL-PRF-22750 serves as an intermediate layer between the primer and a polyurethane topcoat, combining the chemical resistance and hardness of the epoxy with the UV stability and color retention of polyurethane.
Environmental and Regulatory Compliance
Modern revisions of MIL-PRF-22750 include strict limits on volatile organic compounds (VOCs) and hazardous materials. Formulations must comply with EPA and DoD environmental regulations, making them suitable for use in restricted workspaces and under global defence contract requirements.
Low-VOC and high-solids variants are available for facilities operating under air quality regulations or seeking to reduce solvent emissions without sacrificing coating performance.
Need Military-Grade Lighting for Coated Equipment?
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Frequently Asked Questions
Yes. MIL-PRF-22750 remains one of the most widely used epoxy coating standards for defence and aerospace applications and is actively maintained by NAVAIR. Always check the current QPL to confirm which products are currently qualified.
Under proper application and maintenance conditions, MIL-PRF-22750 coatings can remain serviceable for decades. The 1,000-hour salt fog requirement in the specification is a minimum qualification threshold, not a service life prediction.
Actual service life depends on surface preparation quality, coating thickness, exposure conditions, and whether the coating system is maintained and touched up when damage occurs.
It is not recommended. MIL-PRF-22750 coatings are designed to be applied over a qualified primer, typically MIL-PRF-23377 or MIL-DTL-53022.
Applying directly to bare metal without priming reduces adhesion and corrosion protection significantly and is unlikely to meet the adhesion requirements of the specification.