Hi all,
I have been etching, photo-etching and engraving copper, brass and
bronze for 30+ years now so those processes hold very few surprises for
me.
Until now I have always had stainless steel etched by subcontrators,
mainly because the mordants usually recommended seem much more hazardous
than the ferric chloride I normally use on the copper based alloys.
My recent experiments using just ferric chloride alone to etch stainless
steel have revealed a puzzling phenomenon on which I would welcome
comment. The material was prepared as for non-ferrous etching and a
commercial dry-film 'resist' applied in the usual was. On exposure to
the ferric chloride nothing seems to happen for hours but then it becomes
apparent that the resist has lifted to reveal that the resist protected
areas have etched quite deeply whereas the areas exposed to the mordant
all along are untouched and 'as new' i.e. the reverse of what should have
happened. The areas which should have etched away are left as shiny
plateaux and the areas which should have been untouched have been
attacked.
The experiment was repeated using stopping out varnish as a resist but
the same thing happened. It seems to defy logic but I have to believe
the evidence of my own eyes.
What is going wrong here?
Tony Moss
Lindisfarne Sundials
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