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NOTES ON MATERIALS FOR USE IN REDUCING
AIRPLANE RUNWAYS, APRONS AND ROADS
NAVY PASSIVE DEFENSE HANDBOOK NO. 1
Prepared by the Bureau of Yards and Docks
Table of Contents
NOTES ON MATERIALS FOR USE IN REDUCING THE CONSPICUOUSNESS
OF AIRPLANE RUNWAYS, APRONS AND ROADS.
1. General. The information contained herein has been compiled for reference in connection with the study of measures for reducing the conspicuousness of airplane runways, aprons and other paved areas. It must be borne in mind that many field factors influence the selection of the type of material to be used, as well as the coverage and durability that will be obtained; and considerable judgment must be exercised during any field application.
2. Treatments for runways and aprons may be classified broadly as "textured" or "non-textured" and the type of treatment which should be used will depend, first of all, on the porosity of the surface. If the surface is sufficiently roughened or porous to possess natural texture when viewed from the air, the non-textured treatment is indicated. If the surface lacks sufficient natural texture (such as smooth asphalt), a textured treatment is indicated. However, the decision to use a textured treatment will depend on whether or not the additional obscurement obtained from the use of such treatment, when considered in relation to surrounding reference points, justifies the extra time, labor and expense necessary for the application and maintenance of the textured surface.
(a) Application of an adhesive primer to the surface. Tests that have been made to date indicate the emulsified asphalt type, such as that covered by U. S. Army Corps of Engineers Tentative Specification T-1224, Class A, to be satisfactory for this purpose. These materials are usually supplied ready for use, and are best applied by means of a portable pressure-type spraying unit. Their approximate coverage is 40 to 50 square feet per gallon. Typical materials of this type are, adhesive HX (SS-A-674 Type 5), made by the American Bitumuls Co., Baltimore, Md., and adhesive No. 3-M-37 made by the Flintkote Co., New York, N. Y.
(b) Application of the texturing material. Immediately after the adhesive primer is applied, the texturing material should be spread over it, and the surface rolled to uniformity with a light road roller, or a rubber-tired wheel gang roller. Various materials have been tested for texturing purposes, such as wood chips, sawdust, stone chips, pebbles, and slag. Of these materials, wood chips one to two inches long and 1/4 of a square inch, or less, in cross-section (such as hog mill chips or coarse planer shavings) appear to be the most satisfactory. These may be obtained from lumber mills. The use of stone chips, slag, or pebbles, for texturing of landing surfaces, is not considered desirable unless more suitable materials are unavailable. On the other hand, experimentation with flexible materials such as chopped corn cobs, cotton-seed hulls, chopped waste leather, or waste tan bark is to be encouraged, especially where such materials are plentiful and cheap.
(c) Staining or painting of the texturing materials. A thorough study of all of the available test data suggests that four types of paint or stains merit consideration for this purpose; however, it should be borne in mind that, regardless of which type is used, care must be taken to apply only enough of the material to color the texturing substance. The application of an excessive amount of paint or stain will result in the filling of the voids or interstices, thus destroying the texture.
(a) Resin Emulsion Paint, similar to that covered by Bureau of Yards and Docks Typical Specification No. P-2. This type is best applied by spraying, and should be thinned according to the manufacturer's directions. It may be thinned with water for application under normal climatic conditions or with gasoline or mineral spirits for application in very cold or damp weather.
(b) Oleoreslnous Paint such as that covered by U. S. Army Corps of Engineers Tentative Specification T-1279. This type may also be thinned with water or petroleum solvents (gasoline or mineral spirits) and the manufacturer's directions should be followed as to the amount of thinning required for spraying. When thinned with water an emulsion is formed which will be somewhat similar in properties to the paint covered by Y&D Typical Specification NCK P-J, while thinning with petroleum solvents produces a straight, unemulsifled oleoresinous paint. The choice of thinner is dependent on the weather conditions at the time of application.
(c) Bituminous Paint, such as that covered by U.S. Army Corps of Engineers Tentative Specification T-1224, Class "B". This type should be thinned with water according to the manufacturer's directions and is best applied by spraying. If the texturing substance is
wood, better penetration of the paint is obtained by the dampening of the surface with water before applying. In any case, after the paint is sprayed it is recommended that the surface be drag-broomed to break up any formations of paint skins. One of the undesirable characteristics of this type of paint appears to be its lack of color retention.
(d) Pigmented stain, such as C. K. Williams Co.'s (Easton. Pa.) "Colwood Stain". This material is composed of pigment, water, and glycerine and appears to be quite satisfactory where wood is used as the texturing material. It is best applied by spraying.
Surface: Smooth Asphalt.
Materials: Wood chips; penetration grade bitumuls (asphalt emulsion) HX (SS-A-674 Type 5); and bituminous emulsion paint.
Coverage: 27 to 38 square feet per gallon for adhesive; 175 to 25Q square feet per gallon for bituminous emulsion paint; 100 square yards per cubic yard of wood chips.
Method of Application:
(a) Wash off the surface to be treated by hosing thoroughly with water; then broom the surface until it is clean. After brooming, sprinkle the surface again, this time at the rate of about 1/10 gallon of water per square yard. This final sprinkling will permit of more effective penetration of the surface by the adhesive, the application of which follows.
(b) Apply the emulsified asphalt by means of a pressure-type spraying unit. The coating should not be heavier than that obtained by using one gallon to each 27 to 36 square feet.
(c) Immediately after the application of the adhesive, spread the wood chips over the bitumen-covered surface at the rate of about 1/100 cubic yard of chips per square yard of surface.
(d) After dehydration, the surface should be rolled to uniformity, preferably with a rubber-tired roller or with rubber-tired trucks, and the excess chips then broomed off.
(e) The surface is now ready for application of paint or stain. If bituminous emulsion paint is used, the surface should be drag-broomed shortly after application to prevent formation of paint skins.
Note: The type of adhesive used should vary with the regional climate. In no case should it remain sticky or viscous after it has had the texturing material rolled into it. The grade to be used should be determined by tests.
6. Non-Textured Treatments. Non-textured treatments consist of the application of a lustreless paint or stain to a surface for the purpose of toning it down. They are usually one-coat applications, and require considerably less time and labor for application and maintenance than do the textured treatments.
7. For non-porous surfaces, by which is meant any surface that does not possess suitable natural texture when viewed from the air (for example - smooth asphalt), a resin emulsion, oleoresinous, or bituminous paint (such as has been discussed in paragraph 4 above), color which will blend with the surroundings, may be applied. These same type paints may also be used on porous surfaces if necessary but tests made thus far indicate that most of these paints have a tendency to fill up the pores of the surface, thus considerably reducing the natural texture. For this reason the application of penetrating stains would be much more effective. Stains of this type are still in the experimental stage, some difficulties having been encountered in obtaining an even spray coat and fastness of color. Stains made with an oil base have not stood up well under test.
PAINT; CAMOUFLAGE, RESIN-OIL-EMULSION TYPE
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Via Ron Smith National Archives & Records Administration, College Park
Bureau of Ships, General Correspondence 1940-45
Transcribed by RESEARCHER @ LARGE. Formatting & Comments Copyright R@L.
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