STANDARD SPECIFICATIONS OF RUBBER STOPPER Test Standard Specification           Shore Hardness 'A' Butyl Bromo Butyl Natural Latex Specific Gravity 35 To 45 40 To 50 40 To 50 25 To 35 ASH% 1.15 To1.22 1.18 To 1.22 1.18 To 1.22 .92 To.98   25 To 32% 40 To 45% 32 To 36% 2.50% IP'96 Fragmentation Test Total no.of fragment is N.M.T.10 except in the case of BUTYL  Rubber Closure where the total no. of fragment is N.M.T. 15 Sterilization Test Shall not soften, become tacky & there shall be no visual change in the Closures Clearity  & Colour of Aqueous Extract Clear    &  Colourless pH of Aqueous Extract N.M.T. 0.03 ml of 0.001 M NaOH or 0.8ml of 0.01ml HCL is required to change the colour of the soln. To Blue or Yellow respectively. Light Absorption The Absorbancy is N.M.T. 2.0 Reducing  Substances The difference between the titration volumed is N.M.T. 7.0ml Heavy Metals The colour produced in the test solution is not darker than that produced on the standard solution. Residue On Evaporation The residue weight N.M.T. 4.0 mg as compared with the blank.