I use a few small dots (little finger nail size) of the glow in the dark tape at light switches in my darkroom plus I always put me between the dots and the film when loading thereby shielding the film from any possible fogging. I tested for fogging and the only time I got any was when I put the film or paper directly on the dots. When you are in total darkness even a tiny spot of light is easy to see, you don't need a big piece.