I don't know if my PM reply got through, so here it is again with apologies for a kind of repetitin on John's comments above

"Yes, you wax the back so that the paper becomes more transparent - The way an oil stain on a bit of paper is brighter - I don't think workers using salted paper had the luxury of special wax, so I would suggest a clean white wax carried in by some solvent that will not lift the emulsion

However, these things can only be tested by you in your situation - I would like to hear your results, as Rae is wanting to stretch her PH photography - See http://www.jbaphoto.com.au/raestarr.html - Using me carrying my 10x8 camera and me still being her darkroom boy!

Have fun, that is the main thing with projects like this, yes it is research in the true meaning of the word, but can still be fun