Derek
You'll find a reference to dichromate in salt printing on p156-7 of 'The
Keepers of Light' which I suspect you have - if not it is worth getting. The
solution here is 2 grams to 28ml - and he suggests adding it as necessary to
the salting solution - starting from 3 drops per 28ml it will show some
effect.
You should keep the paper away from light after slating and sensitise and use
as soon as possible.
Personally I found the best results were from getting the negs right. It is
some time since I made salt prints, but I seem to remember experimenting with
a very small amount of dichromate in the silver solution to give a _faint_
colour that made it easier to see where I had brushed the solution on.
You are supposed to get less contrast printing using fast light sources such
as sunlight, and more with slower printing. Working here in the UK I found
that on dull winter days I could put the printing frame out in the back garden
when I left for work and bring it in when I arrived home to get a perfectly
exposed result!
Peter Marshall
On Fixing Shadows, Dragonfire and elsewhere:
http://faraday.clas.virginia.edu/~ds8s/
Family Pictures & Gay Pride: http://www.dragonfire.net/~gallery/
and: http://www.speltlib.demon.co.uk/