Phosphors come in a handful of colours, each with its own afterglow. We built three tubes and lived with each for three weeks.

Night vision

Amber is kind to dark-adapted eyes but reads poorly at small sizes. The long-afterglow green, P39, gave the radar a beautiful trail but smeared the countdown. P31 was the balance: a crisp green with a short, soft tail.

One colour, everywhere

Once the tube was green, everything else became quiet around it: an eggshell shell, chrome, brushed aluminium and one red for the needle and the lamp. The site you are reading uses the same four.