Webbing agent sprayed from a standard spray gun produces long cobweb-like 

 filaments that bridge over the gaps or voids to be sealed. In the event that taping 

 has been used to reduce the space, these filaments do not pass through the grid 

 or space but will attach themselves on each side of the gap. This crisscross spray- 

 ing should be continued until a translucent film having the appearance of a fairly- 

 thick cobweb is built up. It need not be a solid sheet but only strong enough to 

 withstand spraying of successive coats of sealing compound without rupturing. 

 It will tend to sag when first applied but as it dries it will shrink and form a tight 

 background. Under normal temperatures webbing will be sufficiendy dry within 

 10 or 15 minutes and ready for the final application. 



Coloring for Inside Work 



When spraying the interior of a building where visibility is poor, coloring agents 

 may be added to the plastic in order to bring out distinctly the area sprayed. 



PMA 17508 



figure 14. — Small cracks in concrete wall sealed with plastic. 



Yellow, red, and blue dyes were used by the Navy but have not been found 

 practical for permanent application. They can be used, however, as the material 

 lades with aging and the resulting color will not be objectionable. 



Preparation of Material 



In figure 3, page 5, plastic compound is shown in the pressure pot ready for 

 application. When webbing agent is added or when pigment is required, it is 

 necessary to agitate the solution until it is evenly mixed. Agitation is also 

 required in cold weather when webbing solution sometimes separates after stand- 



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