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Hello Richard,
If you can't get rottenstone, tripoli (from fine
wood finishing supplies, violin makers, etc) or just plain powdered whiting (for
blanking-out greenhouse windows) will do. French chalk suffices at a
pinch.
Drop a small amount on the plate (size of a small
pea for quarter plate) and drop a few drops of distilled water on it to make it
into a slurry. I use ammonia instead of water for wetplates, some use
acetic acid, but these might affect your chemistry. Rub the whole surface
of the plate in different directions using a small 'rubber' or soft cloth or
tissue. Wipe of the residue with another cloth. Finally, buff with a
chamois leather reserved for that purpose, and store. A test is to 'huff'
on the plate to mist it with your breath - if the layer left by your breath is
totally even, all residues are gone. Not infallible, but a good
guide.
Before coating the plate, a quick, light brush with
a very soft brush (be aware that some brushes or over-enthusiastic brushing may
leave brush marks in the coating, even if you don't see them on the plate before
coating) or an air-puffer will do.
Regards,
Neil.
----- Original Message -----
I'm searching for glass cleaning concoctions for preparing dry-plates,
any suggestions? Up till now, I've been using Sodium Carbonate 1tbsp
in hot tap water and kitchen towel. This seems to work quite well, 'till
the plate dries and I'm left with very faint marks caused by residual
carbonate. No matter how much I rinse, I still get these marks.
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