After lots of looking & reading lately, I plumped for a ready made, water based wash to use over Tamiya acrylic / Future & gave it a blast - lets say it wasn't the cleverest stuff I've ever used, it was exceptionally grainy (think water & sand) no matter how much I mixed it.
Anyway, long story short I gave an enamel wash a try, used white spirits & Humbrol at 10:1 & wow, goes on a dream, & comes off a dream.
The only problem is that it's coming off just a bit too well in areas, leaving some finer panel lines with no wash in them............. I'm using soft paper towel dampened with white spirits for removal, is there anything else I can do to leave more wash in the panel lines (it's only being used to highlight panel lines of a clean aircraft, so I don't want any staining or dirt - just panel lines).
Thanks.