Healthy hair should stretch up to 30% of its length before snapping. But if your hair is heat-damaged and dry, it will break under tension. Khairpep Transforme Masque, £47.50, promises a 120% improvement in elasticity from the first treatment. Ghd Advanced Split End Therapy, £19.95, ghdhair.com, seals splayed ends so hair looks smoother for up to 10 washes. Tresemmé Heat Defence Styling Spray, £5.50, is a must if you love your heated tools, providing protection up to 230°C.