(We recently changed website platforms and lost all the captions for these pictures. We’ll get them back in place soon.)
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Note the ripples where the material is on a vertical surface. Asphalt would harden completely and would not develop ripples like this.What kind of roof is it, coal tar pitch or asphalt? A quick test will show you: put a small piece of the roofing material in lighter fluid, wait a few minutes, and you’ll have your answer. The coal tar pitch (on the left) turns the fluid a bright yellow-green, while the asphalt turns it brown.
