Regarding part of a previous response to the pink ring discussion, pink ring doesn't necessarily result due to "porous" electroless copper or small voids. I suppose it can but consider this: occurrrence of the dissloution of the oxide takes place in acid copper only when the current is on. Run some tests with and without current. Put a load of boards in an acid copper tank for the full plating cycle (e.g. 1 hr.), without current and there should be little or no pink ring. Put the boards in an acid copper tank with any kind of normal plating current density and the dissolution should occur within the first 5 minutes of plating. The acids that can cause the oxide dissolution can also be present before electroless copper, i.e. microetch, pre-dip, catylyst, and/or accelerator (if one is used). This suggests that the dissolution is electrolytically influenced.