  A Comparative study has been performed on Resistive Plate Chambers made of
different grades of bakelite paper laminates, produced and commercially
available in India. The chambers, operated in the streamer mode using argon :
tetrafluroethane : isobutane in 34:59:7 mixing ratio, are tested with cosmic
rays for the efficiency and the stability with cosmic rays. A particular grade
of bakelite (P-120, NEMA LI-1989 Grade XXX), used for high voltage insulation
in humid conditions, was found to give satisfactory performance with stable
efficiency of > 96% continuously for more than 110 days. A silicone treatment
of the inner surfaces of the bakelite RPC is found to be necessary for
operation of the detector.
