Take Ivory black or any dry colour and grind (on a slab with a muller) in japan gold size to the consistency of honey (the proportions cannot be given, as one colour will absorb more size than another colour). Now spread the colour on a piece of stout blotting paper, and let it remain for about an hour; this will extract the grease from the gold size. Collect the colour in a pot and thin with benzine, as the latter evaporates quicker than turps, leaving a better flat.