Willesden Fabrics1 are vegetable substances which have been treated with certain compounds of copper and ammonia, the effect of which is to coat and impregnate them with cupro-cellulose, a varnish-like substance which not only protects the surfaces but adds strength to the fibres by cementing them together.
This enables the fibre to resist the weather, and renders it less liable to catch fire. Ropes, cordage, and netting are treated in this way, but the fabrics most useful to the builder are the Willesden paper and canvas.
Willesden Paper is of three classes.
Unwelded (marked WPG 1), or "one ply" paper, is made 54 inches wide, of indefinite length, and is chiefly used for packing.
Willesden 4 ply (WPG 4) is weatherproof and strong, a bad conductor of heat, free from condensation, does not easily catch fire, does not require painting, and is said to be proof against the white ant; it is useful for roofing, sides of huts, etc.
The relative covering powers of this and good galvanised iron are stated by the manufacturers as follows: -
Willesden paper. WPG 4
Weight of one square in lbs. ....
. 15 to 18
103 to 2S0
Area covered by one ton in squares . Willesden 8 ply may be used as panel board.....
. 125 to 150
8 to 22
Willesden Canvas is prepared in a similar way to the paper, and can be used with advantage for most purposes to which canvas is applied, including making hose.
1 Patentees' Circulars.
Wire Wove Roofing consists of a semi-transparent substance, apparently some preparation of linseed oil upon a basis of very fine wire mesh. It is said to be waterproof, tough, elastic, strong, and not affected by atmospheric changes, and is made in sheets of 10 feet by 4 feet and of 10 feet by 2 feet
Emery Paper is not much used for builder's work.
Silicate Cottonl or Slag Wood is a glasslike fibre blown from blast furnace slag. It is incombustible, vermin-proof, and very light, one ton covering 1800 square feet 1 inch thick, and is therefore useful for making floors and ceilings sound and fireproof.