On Sat, 9 Mar 2019 22:26:13 +0000, John Rumm
wrote:

What type, and where would be a good place to get it (the dye that is, I
have the torch!)?

"fluorescein dye" in eBay... coupla quid, it's a orangey yellow.

A very very little goes a very long way! Found on eBay: "Typically 1 gram of
fluorescein LTC powder will successfully colour change 1 ton of water."


Thomas Prufer