That's interesting regarding the media comment Andy. Here in Aus, the guys who do the Hydroblasting (and there aren't a lot) tell me that it is water / vapour but does contain a media. Perhaps the Vapour blasting process is a different beast? The guy I have been talking to assures me that the Hydroblasting won't affect machined surface tolerances / bearing tolerances etc but will definitely mess up seals and bearings.

Really appreciate everyone's assistance.

Cheers
Jim