Dear Richard
Your interesting use of an razor blade reminded me of the abrasion tone
process perfected by that underrated photographic genius William Mortenson,
I remember trying out this technique in the middle 1950's, the process
took a long time to work and as a photograph was used instead of your gum
print one mistake and it was all over.
I often use a razor blade with my Fotempera process, as this process
employs a laminated properlyne plastic substrate, you can scrub away to
your hearts content. ,
In fact I also use, scalpels ,abrasive scrubbing powder, stiff bristle
brushes, brillo pads. and ink rubbers.you can work on the print in a
subtractive scumbling manner , in a wet or dry sate . As you can imagine
this technique of addition and subtraction allows for a tremendous amount
of corrective control, in fact one seldom loses a print you just keep on
working till it comes right, great stuff no waste.
pete
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