Just had an idea for a test patch. Get a stencil set and stencil your street address on the door in GITD paint. This will be a good test of contrast as well as glow time.
A piece of 4X8 plywood would be good for testing this.
Relatively cheap.
The inside of the garage where the headlights shine on the wall when you pull in would be a good place to try it too.
When your headlights are turned off, there will be a nice patch of glowing paint
on the wall where your headlights were shining before you turned them off. :rock: