Dark Grey Silicone Sealant These are photographic images of each silicone sealant. Due to the photographic process and limitations of monitors they should only be considered as representative colours. Soudal Silirub Colour is a high quality, neutral cure sealant. It has been specifically developed for colour matched sealing, based on the RAL system. Application is easy as the sealant comes in a standard tube which will fit in a normal mastic gun. Suitable for providing a strong, waterproof and elastic seal for a wide range of applications in buildings, vehicles, water craft and more.