Thistle BondingCoat backing plaster is first choice for plasterers working with smooth or low suction backgrounds. It's easy to spread and finish thanks to its fine mix and good workability, making it the ideal undercoat on new walls, or for making good old walls before skimming with British Gypsum finishing plasters. Thistle bonding coat is for low suction backgrounds to improve workability. It is easy to spread, rule and darby and takes 1.5 to 2 hours to set.