Drying/Curing Time.

TM 43-0139 c. Coating, Aliphatic Polyurethane, Chemical Agent Resistant (MIL-C-53039) Single-Component. (1) Characteristics. This specification covers both camouflage and non-camouflage color polyurethane coatings. It is a lead and chromate free, single component CARC with a maximum of 3.5 pounds per gallon of Volatile Organic Compounds (VOC) as packaged. (2) Use. CARC is intended for use over new, pretreated surfaces. It is applied over pretreated surfaces after priming with an epoxy primer (MIL-P-53022, MIL-P-53030, or MIL-P-23377). CARC can be applied over thoroughly prepared CARC surfaces. MIL-C-53039 is for exterior surfaces and interior surfaces routinely exposed to the outside (i.e. door ramps, hatches, etc.). (3) Application. Thinning should not be necessary for brush application. It can be thinned for spraying by mixing up to one part by volume of the applicable solvent with four parts by volume of MIL-C-53039. The applicable solvent for all areas is MIL-T-81772, Type I. For adequate camouflage properties, it is necessary to apply the coating to a minimum dry film thickness of .0018 inch (.0046 cm). Under certain temperature and humidity conditions, for more even results, it may be advisable to apply to coats of a minimum thickness of .0009 inches (.0023 cm) each. The coating is very water sensitive and caution must be taken to insure water or high humidity does not come in contact with the coating before it is cured. Once opened, MIL-C-53039 must be used within eight hours, unless stored under a layer of MIL-T- 81772, type I, or a blanket of moisture free air or dry nitrogen. (4) Drying/Curing Time. Curing time increases with lower temperature or higher humidity. At temperatures of 70"F (21°C) and above, MIL-C-53039 will dry within the specification requirements (sets to touch in approximately 15 minutes, dries hard in 90 minutes, dries through in 4 hours, with a complete cure within 7 days). At 60"F (16°C), MIL-C- 53039 requires twice as long to cure. CAUTION Never mix components of MIL-C-46168 or MIL-C-22750 with MIL-C-53039. They are not compatible. CAUTION Do not use CARC on flexible items. Because of CARC's rigidity, doing so may cause cracking of the finish. CAUTION Spray lines used for epoxy should not be used with polyurethanes without complete flushing or cleaning with solvents. NOTE CARC application requires extremely clean surface preparation. Prior to painting, check cleanliness with the red litmus or water break tests. d. Coating, Epoxy Polyamide Enamel, Chemical Agent Resistant (MIL-C-22750) - Two-Component. (1) Characteristics. This specification is for use on the interior surfaces of equipment, vehicles, vans, and shelters. CARC is designed for easy decontamination after liquid chemical agent exposure. Interior surfaces which become exterior surfaces upon opening (ramps, hatches, etc.) should be painted with MIL-C-46168 or MIL-C-53039. Change 3 2-12