previously employed. Where shed roofs adjoin the wall of a building, as illus- 

 trated in figure 21, plastic is easily applied and it makes a very satisfactory seal. 

 Plastic materials may be used in sealing flashings, skylights, and ventilators in 

 warehouse roofs. It is more economical and practical to seal these openings from 

 the inside where this is possible. Work on the roofs of the buildings is compli- 

 cated by the amount of hose required, the distance from the compressor, and the 

 corresponding loss of nozzle pressure at the spray gun. Where this work can be 

 done, plastic will form an adequate seal and resist weathering and the direct rays 

 of the sun. Under Equipment are listed items required for the operation of a 

 spray unit. It is to be noted that a recommendation is made for the use of 100 feet 

 of both air and fluid hose. It can be seen that working at this or greater distances 

 from the compressor will seriously affect the free air delivery. Charts indicate 



Figure 20.— Close-up of roll-down steel door sealed with vinylite 

 plastic coating. Note application of plastic to surface of door. 



that at 80 pounds pot pressure an approximate 25-percent loss would result at the 

 nozzle. It also is important not to exceed this range ot operation unless serious 

 consideration is given to the loss of pressure brought about by the additional hose 



"Tn'outside wall constructed of hollow tile is shown in figure 22 with cracks 

 and imperfections sealed with plastic material. This sealing, which would be 

 extremely difficult under any other method, makes the wall entirely gaslight 

 It is obvious that the labor required to seal such a wall with plastic roofing cement 



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