Hello,
Various fluorescent paints are available in "artists supply shops" and I
suspect the idea is that you place "something" that will fluoresce back
up to the image to allow the lines to show up.
The easiest thing would be to look for a little fluorescent mounting
board or "wrapping paper - (no accounting for taste!) in a colour that
would give a good contrast with your staining procedure, and mount a
tiny bit of that below the stage (If you set it below the condenser and
then put the condenser well off central setting, it should not interfere
with your primary image). This sounds like a really interesting idea.
Never tried it myself but would love to give it a go.
Peter Harris,
AKA <P.J.Harris at reading.ac.uk>