this final preparation of the body before applying paint, you have several methods to choose from. The method that is selected depends on the condition of the existing paint, the equipment available, and the quality of the desired finish product.
If the paint on the vehicle is in good condition (good adherence and without surface defects), go over the surface with a disc sander. An open-coated disc of No. 16 to 24 grit is recommended. This will remove most of the old finish down to the metal. Follow this with a No. 50 close-coated disc to remove any scratches.
If the paint is to be removed from only a portion of the panel, taper the sanded area down into the old paint to produce a featheredge. Follow-up with ,a 150 grit paper in a block sander, and complete the featheredge by water sanding using wet or dry paper of 280 or 320 grit.
Some manufacturers of abrasive paper advise different grits with variations of the above procedure. Follow the instructions of the manufacturer.
For removing paint from the entire vehicle, sandblasting is the preferred method. Among the advantages claimed for sandblasting method are speed, low cost, and a surface that has good paint adherence.
After removing the old paint, clean the surface with a cleaning agent. If none is available, a lint-free cloth saturated with paint thinner can be used to wipe down the surface. This will help the new paint to adhere to the metal and remove the dust and other foreign matter.
Apply the primer coat as soon as possible after the paint is removed. This is particularly important when the surface has been sandblasted, because the surface is practically in a raw state and quickly starts rusting.
Equipment shall be repainted when inadequate protection is afforded against rust and corrosion. Equipment will NOT be repainted merely to change the color or gloss characteristics if the finish is serviceable. Spot painting, in lieu of completely refinishing previously painted sections, should be done whenever practicable. Bare surfaces of body sections and sheet metal exposed by deterioration of paint or by accidents shall be spot painted immediately to prevent deterioration of the metal.
When using any paint product, particularly lead-base paint, all current health and safety regulations will be strictly enforced. Contact the activity health/safety department/office to obtain all applicable regulations and instructions pertaining to a safe painting environment.
All Navy equipment shall be treated and painted in accordance with MIL-STD-1223. Equipment painting shall meet all specifications and standards referenced within MIL-STD-1223. Colors and color numbers that are authorized for use when painting CESE are as follows:
Before painting, a coat of primer should be applied to prevent peeling and flaking where bare metal is exposed. The primer serves as a bond between the paint and the metal of the vehicle. Each coat of primer that is applied should be allowed to dry and must be sanded lightly between coats. There may be occasions to use two coats of primer, but normally one coat is adequate.
Paint and primer must be shaken or stirred thoroughly, thinned with a thinning agent, and ran through a strainer or filter when using a spray gun. One of the "musts" of spray painting is that the paint should have the correct viscosity. This can be determined by following the instruction of the paint can. Too many painters determine the viscosity by the rate at which the paint runs from the stirring stick. This can lead to plenty of trouble, since only a slight change in viscosity can spoil an otherwise good job. This happens because the amount of thinner not only determines the thickness of the coat but also influences the evaporation rate between the time the material leaves the spray gun and the time it contacts the body panel.Continue Reading