Silos and Silage in Colorado. 
47 
free end of the swab material will not be over five or six inches long. 
The hot tar will melt the glue in brushes if they are used. The tar 
should fill all the pores of the concrete and give the wall a smooth 
appearance. The mere painting of the wall with tar paint or thin 
gas tar does no good. 
Cement Washing .—The washing of the walls of concrete silos 
with a cement wash of cement and water, about the thickness of 
paint, has proved just as efficient to make them air and water tight 
as an application of tar. The wash should be put on with a white¬ 
wash brush on the green walls as soon as the forms are removed. 
The cement wash is cheaper than tar and does not need to be applied 
as often. 
Drawing I. 
