Actual Coal Tar Amounts Used The specifier and applicator are responsible for estimating amounts on a job-wide basis. The total amount used will vary due to application technique, rate of application, applicator's experience, temperature, weather, surface conditions, equipment, glaze coatings, water cut-offs and many other factors. The specifier's and applicator's experience must be their guide in determining material estimates. Where reference is made in this manual to application of bitumen while hot, such reference is to the point-of-application temperature range as listed in Temperature: Heating Point Of Application. NOTE: Bitumen temperatures below those recommended at the . point-of-application. can result in heavy bitumen quantities which in turn can potentially contribute to the cause of membrane slippage, or bitumen migration. When roofing bitumens are excessively overheated and/or held at elevated temperatures for long periods of time, their waterproofing qualities are greatly reduced, physical properties can be modified, the volume of fuming is increased and low interply weights may be experienced. In order to achieve the maximum waterproofing performance, it is imperative that Koppers Coal Tar and roofing asphalts be heated within the temperature limitations listed. Close supervision of heating is good roofing practice for all bitumens. If heat is desired during a holding period at the jobsite while material is not being drawn off and replenished as under normal usage, the kettle temperature should be reduced and not permitted to exceed 325 degrees Fahrenheit (163 degrees Celsius) for Koppers Coal Tar or 400 degrees Fahrenheit (204 degrees Celsius) for steep asphalt. The kettle should be full and the lid closed. These temperatures are applicable to job conditions and do not apply to holding or storage in kettles in excess of 4 hours. If coal tar is not to be used for periods over 4 hours, the kettle should be shut off. Koppers Coal Tar may be contained in 1000 gal. (3785L) or greater capacity heated and automatically controlled closed vessel tankers at 250 degrees Fahrenheit (121 degrees Celsius) for periods not exceeding 96 hours. Prolonged storage temperatures for asphalts is 325 degrees Fahrenheit (163 degrees Celsius).  Return to Application Considerations and Specifications