Mr Moss
Many thanks for your useful opinion and you are probably correct about my lack of experience, as I've only been in this business for 20, odd years, so I'm still learning.
However, in that time, I have trialled many products including citrus gels and solvents, for gum removal, with varying results.
I really don't quite understand your point about wick back, as the black marks being dicussed, are from gum removal efforts.
But, as you say, I'm probably not as experienced as you and am missing something !
DP
You don't need thehigh pressure you're using and Mikes comment is absolutely correct.........I just like to give an additional wipe with an impegnated cloth.