Willesden waterproof canvas is often used for waggon covers. Or No. 8 canvas may be dressed with a coat of raw oil 8parts,and turps 1 parti when dry, paint with ochre or one of the earth pigments mixed as usual with boiled oil, turps, and a little patent driers. Hatch covers are made of a wider and cheaper canvas called tarpaulin canvas, and are dressed with Stockholm tar alone, which is applied warm with a brush. Coal bags are dressed with a mixture of Stockholm tar and linseed oil, applied while warm.