General Specifications - Appendix 6


Edition of June 1943


Chapter 2. - Metal Construction, 
Preparation and Priming of Surfaces





A prerequisite to acceptable paint performance is to put the surface in a satisfactory condition for painting; therefore, thorough cleaning is essential.

The cleaning procedure must include a complete removal of rust and mill scale, solvent removal of any oil and grease, and thorough drying.

Painting at temperatures below 32 degrees F shall not be done, except in urgent cases where authority has been obtained.

Under conditions of high humidity, the temperature of the structure should be increased, or the air in compartments cooled and dried to prevent condensation and to maintain a dry surface.

Steel which is not to be galvanized.

Rust and mill scale shall be effectively removed by acid-pickling, flame descaling or wire brushing as described in section C-7 of the General Specifications, or by approved blasting process.

Grease shall be removed with noninflammible solvent and surfaces wiped dry with rags.  If specifically required by the Supervisor of Shipbuilding, pitted surfaces otherwise acceptable may be smoothed out with cement formula 62.

Aluminum alloy.

Whenever possible, cleaning of aluminum alloy shall be done prior to assembly of parts.  Cleaning before assembly shall be accomplished by immersing the part in, or swabbing with, a cleaner consisting of a dilute water solution of phosphoric acid and organic solvents.  The solution temperature shall be about 70 degrees F.  The solution shall remain in contact with the metal for not over 5 minutes.  Residual solution shall be removed, with clear cold water, followed by hot water, until no trace of acid is detected.

When necessary to clean after assembly, the assembled parts shall be cleaned with mineral spirits, benzine, carbon tetrachloride, trichlorethylene or a mixture thereof, in lieu of the solution used for unassembled parts since acid may be retained between faying surfaces and cause serious corrosion or breakdown of paint subsequently applied.

Light sandblasting, following the use of above solvents, is permissible for producing a good adhering surface for paint, provided care is exercised to control the force and direction of the blast as not to distort or damage the material. 

Welded shall have all the traces of flux removed before painting.  This may be accomplished by brushing the welds while immersed in boiling water.  For inaccessible welds, the part may be cleaned by immersing in a cold solution of10 percent sulphuric acid for 30 minutes, or a 5 percent solution of sulphuric acid held at 150 degrees for 10 minutes.  The acid should contact both the inside and outside surfaces.  The above cited treatments shall be followed by a thorough rinse in clean warm water until no trace of the acid is detected.  Residual flux may be detected by leaching the surface with distilled water, and adding a few drops of 5 percent silver nitrate solution to the leach.  A white precipitate indicates the presence of flux.

Galvanized surfaces to be painted.

All zinc-coated surfaces which are to be painted shall be treated with an approved cleaner consisting of phosphates, phosphoric acid, and suitable solvents and wetting agents to enable the surface to be coated with a thin phosphate coating.  Where the galvanized material has not been procured in the treated condition, the solution shall be painted on the galvanized surface with a large brush and allowed to act with cold water, then with hot water, and when dry, formula 84 primer shall be applied.  Care should be taken to minimize handling of the surface following the coating and prior to the application of the primer.

Miscellaneous metals.

Corrosion-resisting steel, nickel-copper alloy, copper and brass that are to be painted shall be cleaned with noninflammible solvent.  Welds shall be brushed with corrosion-resisting metal wire brushes.



Steel not to be galvanized.

Pickled or furnace material, after scale removal and when clean and dry, shall be spray painted with one coat of zinc-chromate primer, formula 84.  Tinted formulas such as formula 84G and formula 84R may be used to distinguish between various types of metals.

During construction, area which become bare or where rust shows shall be touched up after wire brushing with one coat of primer, formula 84.

Before launching, the exterior only shall receive one complete second coat of primer, formula 84.  Above the waterline this second coat of primer shall be tined a dark color such as formula 84D, shall be used also below the waterline on submarines to insure the maintenance of a dark surface should there be any topcoat peeling.

Decks and platforms to be covered with cement, or composition deck coverings (mastic or the like) shall not be given a priming coat of paint, unless the decks during the construction period are to be left sufficiently long for corrosion to be of a serious nature, in which case they shall be painted for protective purposes as directed by the Supervisor of Shipbuilding.  Before coating with cement or composition, the paint shall be removed down to bare metal.

After completion of interior constructions, the after pickling coating shall be touched up.  All surfaces not already painted shall receive one coat of zinc-chromate primer, formula 84.

Zinc-coated metal.

Exterior galvanized structure and the interior of the superstructure of submarines shall be primed and painted.  Interior galvanized structure and equipment except submarine superstructure are normally unpainted, unless painting is considered necessary by the Supervisor of Shipbuilding.

Galvanizing destroyed by welding or cutting, galvanized wire mesh, or expanded metal shall be touched up with one coat of primer, formula 84, and shall be finish-painted the color of surrounding superstructure, except in gasoline or fresh water tanks, where the welded area shall be recoated with zinc, metal sprayed.

All galvanized areas to be painted shall receive one complete coat of zinc-chromate primer, formula 84.

Aluminum alloy.

Frames and stanchions of aluminum pipe berths shall not be painted.

Crew's clothes lockers, bins, shelves, etc., when constructed of aluminum shall be left unpainted.

All aluminum surfaces which are to be painted shall be given a priming coat of zinc-chromate primer, formula 84.  This priming coat shall be applied as soon as possible after the metal has been cleaned, rinsed, and dried.  If necessary, the priming coat shall be touched up before application of subsequent coats.

Where aluminum alloys surfaces are to be made brightwork, the priming coat will not be required.  Such bright surfaces shall, however, be waxed.

Where aluminum materials are to be given finishing coats, or where appearance is unimportant, the faying surfaces shall be coated with zinc-chromate primer, formula 84.  Where the material is to be left bright, as for crew's lockers, the faying surfaces shall be coated with varnish, phenolic type, formula 80.  Each of the faying surfaces shall be painted and allowed to dry before being brought together, and just before being brought together each shall be given an additional coat of the required paint or varnish.

For nonwatertight joints, aluminum shall be protected from contact with dissimilar metals, including galvanized steel, and from contact with wood or other absorbent materials which tend to become water-soaked, by an approved, nonabsorbent gasket material or by sealing compound in accordance with Navy Department Specification 52C12. Canton flannel which has been soaked thoroughly for at least 12 hours in zinc-chromate primer, formula 84, may be used for parts subsequently to be painted.  For parts to be left bright, the impregnating medium shall be varnish, phenolic type, formula 80.  Gaskets of this type shall be installed while wet.

Where gaskets or sealing compounds are used between faying surfaces the second coat (wet) of primer may be omitted.

Wood in contact with aluminum shall be painted before assembly with one coat of  varnish, phenolic type, formula 80.

Sealing compounds, in accordance with Navy Department Specification 52C12, shall be used for such nonwatertight work as joints of ventilation ducts.

Watertight joints between aluminum parts, or between aluminum and galvanized steel, shall be made tight by caulking on both sides and without the use of gaskets or packing, wherever possible.  Where such caulking is not possible, or where aluminum is in contact with material other than aluminum or galvanized steel, canton flannel impregnated and installed as described above, approved gasket materials, or caulking compounds in accordance with Navy Department Specification 52C12, shall be used.

Crevices, such as those occurring between aluminum bulkhead plating and airport and window frames, shall be sealed with sealing compounds in accordance with Navy Department Specification 52C12.

Asbestos paper, or similar absorbent material, shall not be used in contact with aluminum.

All threaded parts of aluminum alloys, whether aluminum alloy to aluminum alloy or aluminum alloy to a dissimilar metal, shall be coated before assembly with an  antiseize mixture of 50 percent zinc dust and 50 percent petrolatum.

Aluminum gratings shall be primed before assembly.

Aluminum airplane tracks shall have all surfaces except wearing surfaces treated and painted in accordance with the requirements for painting other aluminum material.

Bolts which are to be used in clearance holes in aluminum, with the exception of the threaded portion, shall be coated with sealing compound in accordance with Navy Department Specification 52C12 before being inserted in the holes.

The fastenings of aluminum alloys shall be in accordance with the General Specifications for Building Vessels of the United States Navy, edition 1936, Section C-6, except that zinc-chromate primer, formula 84 shall be used in lieu of zinc-chromate iron-oxide primer.

Label plates, regardless of material, which are installed on aluminum structure of fittings, shall be imbedded in a plastic sealing compound in accordance with Navy Department Specification 52C12.

Surfaces of aluminum material which are not readily accessible for inspection and maintenance after assembly, such as the unexposed surfaces of insulation sheathing, quick-operating door guards, etc., shall be given two coats of zinc-chromate primer, formula 84.

Other metals.

Corrosion-resisting steel and copper-nickel alloy will normally be left bright, except when painting is considered necessary for appearance.  Inaccessible areas and metal to be painted shall receive one coat of primer, formula 84.

Copper and brass gage cases, electrical fixtures, hatch and door frames, covers, ladder side stringers, pipe outside machinery spaces and other parts not requiring frequent handling shall receive one coat of primer, formula 84, and shall be finish painted.

Metal plaques, trophies, data plates, and nonferrous metal requiring frequent handling shall not be painted, but for camouflage purposes visible brightwork topsides must be kept at an absolute minimum.


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