This illustrated pamphlet describes preservation of the Wasa following its raising in 1961 after 333 years in Stockholm harbour. Some deterioration of the waterlogged wood hull occurred due to soft rot fungi; iron staining caused discoloration. Initially, the shipwreck was sprayed continuously with sea water to prevent shrinkage and warping (and clean the hull) before construction of a protective structure with environmental control. After scientific testing, impregnation and consolidation of the hull proceeded by automatic spraying with polyethylene glycol (PEG) with fungicides (borax, boric acid) and methylpolysiloxane. A resultant commercial product for treatment of underwater archaeological wood, called Modolog Antiqua is produced by Mo och Domsjö of Sweden. The preservative penetrates the degraded oak and birch cell structure well, protects against fungi and insects, and is nontoxic, a rust inhibitor and fire retardant. Single objects (more than 24,000 were found by 1964) are treated over about a year using a continuous method in huge tanks with automatic control over temperature and preservative concentration. Textiles, ceramics, glass, and metal objects were also found; iron corrosion is reduced to iron by hydrogen or carbon oxide in a special furnace. Data are tabulated on the ship, preservation plant and contractors.