26 BULLETIN 691, U. S. DEPARTMENT OF AGRICULTURE. 



should be followed by a sufficient amount of clean small sized 

 broken stone to fill the surface voids when thoroughly rolled. A 

 seal coat of the same bituminous material should then be ap- 

 plied at the rate of 0.4 to 0.6 gallon per square yard and covered 

 with a sufficient amount of stone chips to just absorb the excess 

 bitumen. Roads of this character may be maintained with oil 

 surface treatments using the materials and the methods given 

 under specifications OC-2 or OH-1. The latter is usually to be 

 preferred. Such maintenance treatments should be applied when- 

 ever the wear comes directly upon the wearing course rock. 



