Here's an interesting post on this subject from pba.com!

Enjoy!

There seems to be a popular misconception that plasticizers in a ball are inherently required to get the ball response (hook)that bowlers expect. This is a half truth. Certain plasticizers may be added to the coverstock resin to control hardness and/or the coefficient of friction, but these are chemically reacted into the polymer network. For all practical purposes, they do not migrate in or out of the ball.  They are locked in place.
 
However, to make the balls porous, the ball manufacturer adds a non-reactive plasticizer into the mix as well.  This plasticizer cannot and does not get locked in place.  Its sole purpose is to worm its way out of the ball as the coverstock solidifies during the curing process leaving behind micropores in the cover that the non-reactive plasticizer left behind as it migrated to the surface. It is these pores that soak up lane oil and promote more hook by sucking up oil from the ball surface that is in contact with the lane surface.  This is the reason why a never used new ball can be baked and oil will come to the surface.  That oil is really non-reactive plasticizer that never quite made it out of the ball at the plant.  This type of plasticizer is not a hook enhancer by its presence, but rather by its absence.
The situation posed in this thread where an old retired ball suddenly seems to have new life is most probably due to the fact that the lane oil that had been lodged in the pores of the ball has had sufficient time to: 1)evaporate, 2)evironmentally degrade, or 3)to slowly be absorbed into the core of the ball leaving the pores once again open to absorb more oil.
If you want to keep your ball in good performance condition, clean it after every use and occasionally give it a light resurfacing to open up the pores that had become clogged with lane grim.

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I've upped my average, so up yours!

Edited on 4/24/2008 7:08 AM