Just a hint about UV viewing light, etc.
What I did at first to make sure I could see the UV ok with the intended light when I first started is mix little bit of dye into some motor oil, just small amount of oil and a drop of dye stir it good and then see if you can see it in daylight, then in a shade, then in a dark place. (using the UV light only, UV light with the special glasses, etc. You will know then if you can actually see the dyed oil and how you need to go about doing the viewing when you get ready to add the dye for the actual leak test.
Most generally I've had to view in the dark to see good dye color.
Another hint:
Sometimes the dye is hard to remove or will not remove even with the dye remover solvent on the surface of where it leaked before and you need to do a re-test after a repair.
I just de-grease the area and then use some flat black Hi-Heat paint and lightly spray over the dye. The new oil with dye will be on top of the paint if it's still leaking.
Then to remove the NEW paint later just wipe with Lacq thinner and a rag and paint brush.