crystalline thermoplastic such as nylon polycarbonate has a specific heat of 0 3 btu lb degree f and latent heat of fusion is 56 btu lb thus if solidsbed breakup of both should occur and an initial equal sized distribution curve for each were to be identical at any particular time and temperature gradient thereafter the remaining particle size distribution of the two different plastics would be expected to be different thus in order to assure that the molded part is ultimately free from objectionable clear specks some unmelt particle size 34 critical threshold value 34 must be obtained before injection occurs below this criticalhreshold value unmelt particles having less than this minimum dimension at this stage will not be a problem because melting continues until finally the molded part solidifies and is determined empirically to be sufficiently complete to yield good quality product free of objectionable melt however above this critical dimension such melting will not reduce the unmelt particles 39 diameter sufficiently to make it not noticeable visually or optically this critical threshold dimension for unmelt will vary from setup to setup and polymer to polymer according to the list of variables mentioned earlier but as a generalization an aperture dimension in the range of 0 020 0 050 inch and most preferably.