Tung oil was used to waterproof Chinese ships as long ago as the 14th century. The thin, transparent oil penetrates deep into wood pores, forming an almost permanent seal against moisture because it never loses its elasticity.
The oil is obtained from the seeds of a tropical tree, the tung tree (Aleurites fordii) of the spurge family - it is known also as China Wood oil.
The seeds found in the heart of the tung fruit (which is the size of a small apple) contain more than 50% tung oil, readily obtained when the seeds are heated, ground, and pressed. The oil is amber-coloured and contains a high proportion of eleostearic acid.
Tung oil is an ideal "binder" or "vehicle", carrying the resins and driers deep into the pores of the wood so that sealer and finish coats practically become part of the wood - drying into an armour-like yet beautiful surface. Uses of Tung Oil
It is widely used as a dryer in varnishes and paints as tung oil polymerizes to a hard, waterproof gel that is highly resistant to acids and alkalies. It is also used as a component of insulating compounds and in the manufacture of linoleum and oilcloth. Although in recent years Tung Oil has been replaced by cheaper alternatives its wide range of uses still allows a great commercial importance.