solidifying the pre polymer by allowing the polymer to cool cooling may be accomplished by using air nitrogen or other medium which would allow the pre polymer to solidify the solid phase comprising nylon 6 pre polymer is then separated from the aqueous phase the following non limiting examples demonstrate the invention 27 8 gm of 6 2 rv relative viscosity nylon 6 pre polymer containing 6 8 wt caprolactam and 0 7 wt cyclic dimer was charged to a reactor along with 2 2 gm water and 0 3 gm nitrogen the mixture was heated to 240 u00b0 c mixed and forced through a 0 0762 cm diameter hole with 600 psi upstream pressure the resulting nylon 6 powder had an rv of 4 4 a caprolactam content of 9 8 wt and cyclic dimer content of 0 8 wt this powder was contacted with cold water 20 u00b0 c for 15 s in a beaker the contents of the beaker were filtered to separate the powder from the water resulting in an additional contact time of the powder and water of approximately 30 s through this process the caprolactam content of the powder was reduced to 1 8 wt and the cyclic dimer content to 0 2 wt the pressure drop was 600 psig this example demonstrates that a pressure drop alone did not result in significant reduction of extractables the process required subsequent contact with water to result in reduction of extractable impurities pressure drop repressurization followed by contact with water to soldify caprolactam pre polymer a 75 wt solution of caprolactam in water was heated in an autoclave to 272 u00b0 c and held.