GLAZING AND PAINTING 107 



the top of the first, and its upper edge rests 

 on the sash bar. This is fastened at the bot- 

 tom with brads or glazing points to prevent 

 its sliding down. The remaining panes of 

 the run may then be placed in the same man- 

 ner, special care being taken to secure the 

 uppermost firmly in place with glazing 

 points. This is necessary because it has no 

 glass above it to hold it in place, and because 

 it acts somewhat as a key to keep the others 

 in position. 



It is best to finish each run from bottom 

 to top before starting on a new run, in order 

 that the putty may cement into a continuous 

 mass. On high and wide roofs, however, it 

 is sometimes advisable to glaze the lower 

 half of the roof, then move the scaffolding 

 and glaze the remainder. 



How to Estimate Putty. The amount of 

 putty necessary to glaze a roof may be esti- 

 mated as follows : A pound of putty, when 

 applied by an experienced workman, will 

 reach about 15 feet along one side of a run 

 of glass or about yY* feet along both sides. 

 To estimate the amount of putty, therefore, 

 multiply the length of the run in feet by the 

 number of runs and divide by 7/^2. This will 

 give the number of pounds required. The 



