Peter wrote
"The standard mix is of course used without the pigment included for the
size, and the average exposure was found to be 10 to 15 secs, although I
watch my students like a hawk, we got from time to time exposures of 10 to
15 mins, giving us a nice chocolate brown colour, this things are
inevitable in a college situation, and gives us all a giggle ;-).
You can only use this sizing method once,
otherwise an unpleasant Dichromate stain builds up, resulting in a
degradation of the image."
Why would you want to do it more than once ?
"I am still testing my dulux delight sizing method and am in the process of
trying out other brand names , I believe our emulsion paint is called
latex across the pond the term latex in England is usually applied to
rubber goods,how exciting ! .;-)"
I think that you will find that mat polyurethane will do the job quite well. But
is it archival ?
Terry King