> > > They suggest that I need to use a there "Universal Developer"
> > > 690-849. Is this really needed as it is expensive.
> >
> > They suggest in one of their etching pdfs (232-3686) that sodium
> > hydroxide can be used instead


Caustic soda / sodium hydroxide / lye is a common developer for some etch
resists. It attacks the unexposed resist but works much more slowly on the
exposed resist. Google has lots on this. You can buy caustic soda from
grocery stores or "chemists".

Typically people seem to be using 7 gm/litre (a bit under 1% solution).
One of many refs

    http://www.xs4all.nl/~pquanjer/spectechn/photogravure.htm

The exposed developer can often be removed after etching with acetone - or a
scouring pad.



        RM

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.