Sandite is a substance used on railways in the UK, Ireland, US and the Netherlands to combat leaves on the line, which can cause train wheels to slip and become damaged with flat spots. Sandite consists of a mixture of sand, aluminium and a unique type of adhesive. Leaf build up on the railhead can also cause signalling issues and 'disappearing trains' on the rail control systems (because of the electrically insulating effect of the leaves, which can prevent operation of track circuits).