Luminous paint needs the energy to glow, so you should let the paint absorb sunlight or lamp light and bring it into the darkness to see. The first light will glow strongly then weaken. If you want to see more glowing, turn on the light for a few minutes to provide some energy for the paint.
Here is the glow time: Aqua, Neon: 6 – 10 hours; Purple, white, red: 3-5 hours; the remaining colors: 2 – 4 hours. The time is calculated when the paint has absorbed enough energy by sun drying for 15 minutes, or under the light for 1 hour.