SURFACE TREATMENT

TM 43-0139 Over CARC. CARC may be applied over sound CARC surfaces that have been solvent cleaned. Items painted I with CARC will not normally require stripping. Exceptions are corroded areas and aircraft with severe weight restrictions. These surfaces shall be cleaned of paint by Plastic Media Blasting (PMB) at 40 psi, whenever possible. This is the preferred method of removing CARC primers and enamels. After paint removal, the entire surface will be cleaned in accordance with MIL-STD-186 or MIL-T-704 and tested for cleanliness using the water break or red litmus test. (2) For application of other finish systems. Previously painted surfaces that are to be painted with finish systems other than CARC should follow the requirements and procedures of the individual finish systems and specifications involved. 3-4. SURFACE TREATMENT a. General. Bare metal surfaces to be painted with CARC coatings or vinyl paints will be coated immediately after cleaning with pretreatment primer conforming to DOD-P-15328; this pretreatment will be used under conventional paints only where specified. This wash primer will not stick to steel surfaces which have been treated with metal conditioner, MIL-C-1 0578, Type II. Anti-fouling paint will not be applied over bare metal, since the copper in this paint will corrode the steel. Aluminum may require pretreatment with MIL-C-5541. Whenever possible, MIL-STD-193, MIL-T-704, or other applicable finishing documents should be consulted. b. Use. Pretreatment primer DOD-P-15328, is used as a bonding agent and to provide temporary protection against corrosion. In general, it may be applied to all bare surfaces, both exterior and interior. Ventilate and take proper precautions pertaining to flammable materials. 3-5. TREATMENT OF SPECIFIC SURFACES a. Treatment. Pretreatment of surfaces is generally used as bonding agent between the surface of the equipment and follow-on coatings. It provides temporary protection against corrosion. b. Ferrous Metal, Zinc, or Cadmium Surfaces. Ferrous metal, zinc, or cadmium surfaces shall be treated as soon as possible after cleaning, as specified in paragraph 3-3 above, and as follows: (1) With an organic pretreatment primer conforming to DOD-P-15328, or with a zinc phosphate (Type I) or iron phosphate (Type II) chemical conversion containing in accordance with TT-C-490. (2) Any evidence of rust or contamination on a previously cleaned surface shall be cause for recleaning prior to painting. c. Aluminum Surfaces. Aluminum surfaces shall be treated as soon as possible after cleaning, as specified in paragraph 3-3 above, and as follows: (1) With an organic pretreatment primer conforming to DOD-P-15328, or in accordance with MIL-A-8625 or MIL-C-5541. (2) Any evidence of corrosion or contamination or previously cleaned surface shall be cause for redeaning prior to painting. d. Magnesium Alloy Surfaces. Prior to painting, magnesium alloy surfaces shall be treated in accordance with MIL- M-3171, Type I or III. Treated surfaces that become scratched in handling shall be touched up in accordance with MIL-M- 3171, Type I. e. Wood Surfaces. Properly seasoned wood shall be sealed prior to application of CARC with a polyurethane sealer covered by NSN in Table B-12. Single and two component sealers are listed. Glue used during construction with wood shall be treated with sealer after construction. Unless otherwise specified, wood shall be treated prior to sealing in accordance with MIL-T-704; i.e., dried to a moisture content no greater than 20% and pressure treated in accordance with American Wood Preservers Bureau (AWPB) LP-2 (above ground) or LP-22 (ground contact). Only Ammoniacal Copper Arsenate (ACA) or Chromated Copper Arsenate (CCA) preservatives shall be used. Alternate processes are available when repainting or when pressure treatment is not available. Change 3 3-3