Plastic materials, like polyethylene, or ethylene are used in bulk for manufacturing products of daily use, such as soap stands, liquid detergent containers and what not but in here we are clearly focusing upon the plastic material which are subjected to environmental stress. The stress are often experience by surface contact agents such as soap or chemicals, majorly detergents. These type of material are not easily absorbed by the polymer surface and by being in touch with the surface of the plastic material they generates crazing process in the polymer. Crazing is natural phenomenon as per which it produces a fine mesh of cracks on the surface. It then precedes on developing more cracks under tensile stresses. This can later lead to material damages and a final crack in the object.

To measure the amount of stress cracking which may develop in the material, one of the most widely used method is the Bell Telephone test method. It is also know by the term bent strip (BS) ESCR test. To prepare the sample a small piece of a plastic material which is to be tested is cut as per the standards and notched on the centre. Then using bending equipment, the specimen is bent and fitted in the sample holder which is again designed as per test standards (ASTM D1693). The holder along with the attached bent strip is immersed in the test tube having a reagent against which the sample is to be tested (For instance, liquid detergent, in most cases.)

The prepared test tube then blocked with a plug and immersed in hot water bath to be in a rising temperature. This entire apparatus is then processed for a defined time period. And the results can be visually inspected. The most reliable testing machine for perform ESCR is ESCR tester. The test machine is digitally controlled and is equipped with PID control system. Standard accessories with the machine include devices for preparing the sample along with a notch, Sample holder and test tubes. Integral water drain system is also available.