Page 161 control and signal building 276 



Eoports from field parties indicate that the grade of white signal cloth available 

 at Navy depots in 1941 is superior and more suitable for signal dressing than that 

 purchased commercially. It is a tough material and withstands wind and weather well. 

 It is described in the General Schedule of Supplies as Sheeting, Cotton, Gray, 36 inches 

 in width, and is listed as Stock No. 27-/5-7670. The cost in 1941 was about 6 cents 

 per yard. 



Signals are dressed with cloth in different ways. They should be varied in size 

 and shape to avoid a similarity between adjacent signals. The most frequently used 

 types are crossed banners, flags, cloth tacked on the bases of tripods, cloth tied on 

 bushes, cloth wrapped around tree trunks and stumps, etc. 



Target boards on tall hydrographic signals and slats on centerpoles have been 

 whitewashed or painted black or white. If these boards are wrapped with white or 

 black signal cloth the targets will have greater visibility, for cloth is a better reflecting 

 surface and will not fade so rapidly. All large pieces of signal cloth should be pierced 

 with random slits, 4 to 6 inches long, to serve as vents to ease the wind pressure and to 

 discourage vandals from stealing the cloth for their personal use. 



276. Whitewash 



Whitewash, made from unslaked lime, is a convenient, economic, and satisfactory 

 material with which to mark signals for inshore hydrography, especially where the 

 coastline is rocky. Its use is not limited to rock surfaces, however. Boards on tripods, 

 small buildings, driftwood, stumps, tree roots washed up on the beach, pieces of wreck- 

 age, and almost anything that will serve as a signal can be whitewashed to advantage. 

 Even bluffs of crumbling dirt or disintegrated rock can be sprayed with good results. 



Pulverized unslaked lime is usually sold in paper sacks or wooden barrels. When 

 it can be purchased as required this is satisfactory. It deteriorates rapidly, however, 

 and when a stock of it must be kept on hand for use over a considerable period of time, 

 it should be purchased in watertight metal containers, each containing about 90 pounds. 



Whitewash for marking signals is made by filling a bucket about one-quarter full 

 with pulverized unslaked lime and adding about 1 gallon of water. As the mixture 

 boils it should be stirred and a little water added from time to time to keep it from 

 boiling over. When the boiling ceases, more water should be added while it is being 

 stirred until it has a thick soupy consistency. The mixture should be stirred with a 

 stick at least 3 feet long from a position as far away from the bucket as practicable 

 because it is likely to spout up while boiling; it is not pleasant on the skin and is 

 decidedly painful and may be dangerous in the eyes. 



Whitewash is usually put on with a brush, but spray guns, similar in type to those 

 used for spraying fruit trees, have been used very successfully. Their principal 

 advantage is in whitewashing objects which cannot be easily reached with a brush, and 

 in spraying rough or crumbly rock which cannot be coated thickly and evenly with a 

 brush. They may also be used for spraying whitewashes on cliffs that rise almost 

 vertically from the water where landings are difficult or impossible. The liquid must 

 ee thinner than when a hand brush is used and must be strained before use to keep the 

 hose and valve from becoming clogged. After use each day, the sprayer must be 

 thoroughly cleaned with fresh water to wash out all whitewash and salt deposits. 



Wliitewash is most permanent when it is applied to a dry rock surface. It is a 

 waste of time and effort to whitewash dm-ing a rain. Near the high-water line white- 

 wash will soon be washed off" or become so dim as to be indistinct and be confused with 

 guano deposits. One bucket of whitewash is ordinarily sufficient to make a signal 



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