Chromated Copper Arsenate (CCA)
CCA was developed in the 1930’s, and is one of the most popular methods of wood preservation around the world since the 1970’s.5 It is commonly used in the treatment of outdoor decking, fencing, playgrounds, marine facilities, utility poles, commercial and agricultural construction, highway structures and other infrastructure.
It is a solution of chromium, copper and arsenic oxides, with copper acting as the primary fungicide, arsenic acting as a secondary fungicide and insecticide, and chromium acting as a fixative agent responsible for the binding into wood. Being a water soluble compound, it is applied to wood using pressure impregnation, and provides a long lasting protection from fungi, bacteria and insects as well as resistance to UV degradation.
Studies have shown that leaching of CCA into soil is minimal to zero, and although some countries have placed restrictions on its use, further studies have failed to show any adverse effects or significant leaching, and CCA continues to be used for many wood preserving applications all over the world. Water repellent properties of CCA can be increased by the addition of wax emulsions.