This Ronseal RSLGPBWH15 is a 15ml Pen with re-sealable lid Need to touch up painted or discoloured grout? The Ronseal One Coat Grout Pen quickly and easily transforms the surface giving a durable and waterproof finish in one coat. So now there's no need to re-grout. Colour: Brilliant White. Available in Two Sizes (ml). Areas of use: Interior tiles. Approx. number of coats: 1. Application: Pen. Drying time Approx.: 24 hours. Protection level: Medium.