There are different schools of thought when it comes to this and I thought I'd put it to the group. I've heard people say that if peel ply is used there is no need to key the area up before laminating/painting/glueing. I've also heard the opposite that even if you have peel plyed once the laminate is no longer 'green' use must key up before adhering to it. 

Peel ply is designed primarily as a removable pourous barrier between the laminate and other part of the bagging stack.  Providing a good surface for secondary bonding is a secondary function and in essence a byproduct of the peel ply's surface texture. In most cases, the peel ply finish will be fine, however a good key of the surface may well give slightly better results.  Also be aware that there are some "release-coated" peel ply's on the market which are coated in release agents to aid removal.  These almost always leave a trace/layer of release agent on the finished part and will need a thorough key and clean to ensure all traces are removed to get a good bond.

If in doubt, we always recommend full surface preparation prior to bonding. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant