BRUNSWICK BLACK, a useful black varnish used in Great Britain for painting stoves, grates, fenders, and all inside iron work. It possesses excellent anti-corrosive and preservative properties, and thus effectively prevents the rusting of all metal surfaces on which it is applied, while at the same time imparting to them a highly lustrous black finish.
The process of manufacture consists in melting asphaltum in large iron pans set in brickwork over a fire. When the fusion is complete and the molten mass is in a thin fluid condition, the fires are withdrawn and sufficient turpentine or turpentine substi tute is added to thin the mass to a consistency which renders it easily applicable.
A proportion of common rosin is frequently added to the asphal tum in order to increase the lustre of the Brunswick black, but if too much is added the denseness of the black is impaired. The best varieties of Brunswick black contain a proportion of boiled linseed oil which is incorporated with the asphaltum during the melting process and serves to toughen the black, and thus prevent it chipping or powdering off.
The following are two representative formulae for the manufac ture of Brunswick black : (I) (2) Asphaltum II21b. Gilsonite II 21b.
Dark Rosin 5olb. Boiled Linseed Oil 2gal.
Turpentine 22gal. Turpentine 25ga1.
Brunswick black dries in about 2-3 hours. It is only suitable for inside use and should not be used on exterior work, as owing to its composition it lacks durability and if exposed to weather ing influences would rapidly deteriorate and powder off. In painting exterior ironwork only black varnishes specially manu factured for outside use should be used.