[Malcolm T]

Looks like citric acid is on the menu then as well. Yes warming the solution does speed up the process or so i,m led to believe.
Initially this all started out as a way of etching a pcb on the cheap without ferric oxide, however it kind of went in another direction !
I looked at some you tubes on etching and plating metal components with electrolysis and car battery and they are very interesting and i take your point about difficult to plate areas where the solution seems to work less effectively.
Perhaps a small plastic aggitator fan in the solution would solve this i dont know? it would seem so thinking about it because it would wash away old solution and introduce new to that area like in a photographic development tray when processing film or paper. Worth a try i think.