b'_ u_e_s_t_i_o_n_s_ & A s_w_e_r_s _ _ _ _ _ _______ _ _ ______ _ _ ., _ _n_Questions Aboutand Asphalt Coal Tar Explained Q.InEnglish,is Equiv Q.Can I use asph t over coal tarAsphalttar are incplainwhatal and coalomemperatureVT)?patible, but withinrtain limits ceiscous T (E or vice versa? A.Conting statemen havethey can be used. If you mix coal A. In layman terms, EVTsimplyicti ts is eentar and asphalt to an pocertai int, that temperature at which the bitu b made regarding whether or not asphalt roof covering can betheyappeartobecomp le. men (aspha or coal tar)atibltprovides the proper adhesion in the appli coa ndpo is applied over al tar roof cover Beyo thisint therea sludging or vice versa.inci ing effect,in aular cation of built-up roofs. In addi Disturbingresultinggrantsbolste material with an o yface of litil surtion, it is important to lay theden can be described tor properamountofbitumenthe theory that asphalt and coal tartleue.e h dis vered val Roof rsavecobetweenlayers and to h theare incompatible, and against thisthis totheir dismay whenthey ave aspha and expe have melted bothltcoal least amount of voids. Anri are records of roof applications enced roofing mech icthewhereand coal tar cover tar in the same k If tarred felt an usingasphaltettle. ings wereover each otheriswith asphaltasphalt felt bitumenspreaderknows,evenappliedusedor w ut dam hused with coal tar the saturants thoughhemaynot beabletoitho aging reactions. Bottheuni it the explain why in technical terms,viewsarerightandbotharemelt infelts andte w h whenthe bitumenhas thebestwrong.Continuedpage 10 on flow quantities and isthe corat rect EVT.you tell the differenceBRING Q.How can between asphaltcoal tar? and are A. Theresubjective tests that canbeused,such as the ado r, particularly when the materials are burned. Also, there are some solubility differences. However, perhapsthebest method depends upon the difference in unit weight. graviWater has aty of 1.00 and asphaltgenerally have awillgravity range of 1.00 to 1.02. Therefore, aof asphalt dropped into ball waterl fall very slowly though wilWhereas coal tar the liquid.,will drop more or less like aor stone ak. roc ELMENDORF. We con toke it. Every shingle we make complies with the MRCA recommendation to meet ASTM D3462 requirements. Including the specification for~ tear strength as measured on the Elmendorf pendulum tear tester. That\'s a" claim no other manufacturer can make.~ Visit us on the Internet at www.certainteed.com or coll l-800-782-8777 and ask for ASTM proof.CertainTeedll'