First, use your nose to smell whether there is an odor. The normal EPDM material will have a little mellow smell, which is almost not smelled.

Second, wrap the sealing strip as tightly as possible on the profile and place it on the roof or in a sunny place. See whether the contact surface of the profile surface and the sealing strip is stained or discolored, whether the dust on the surface of the sealing strip is yellow (oil is easy to absorb soil), seepage oil, and whether the hands are dirty.

Third, some cheaper seal fillers will be more, so the surface will not be very shiny, and those that are cheap and have a bright appearance are not desirable.

Fourth, look at the proportion. Adding heavy calcium seals, you stretch back and forth several times with your hands, a small amount of white powder will appear on the surface.