Joico smooth cure thermal styling protectant is a flat iron or curling iron spray that seals in smooth cure leavein rescue treatment and finishes the smoothing processhydrolyzed keratin forms a durable flexible sacrificial shield of keratin that reacts with sunlight and pollution to protect hair from damage and colour fadingwhile sealing in your smooth style with heat tools hair is protected from thermal damage up to 450f and will remain smooth soft and shiny for up to 72 hours even in high