Weight of Fibre: The One Number Every Dye Recipe Is Built On

Weigh the fibre bone dry before it goes anywhere near water, and use that one number for the whole day: the scour, the mordant, the dye, and any modifier afterwards. A kitchen scale reading to a gram is enough for a 100 g skein. For samples under about 20 g, a jeweller's scale reading to 0.1 g is worth having, because a gram of error on a 10 g sample is a tenth of the recipe. Tie a tag on with the weight written on it. That sounds fussy until the third skein of the day goes into the wrong pot — and it is also the first line of the dye record, which is its own rung. If the fibre has been sitting in a damp room, it is worth drying it in a warm place for an hour first. Wool at 80% relative humidity can carry 15% of its own weight in water without feeling damp at all.

The fibre, the mordant and the water are all easy to weigh. The dyestuff is not, because the same plant is sold in forms that carry very different amounts of colour. **Fresh versus dried.** Fresh plant material is mostly water. Fresh weld or marigold is typically used at three to four times the dried weight for the same depth, and the exact factor depends on the season and on how it was dried. **Whole versus ground.** Ground madder root gives up its colour far faster than chopped root, so the same weight gives a stronger first bath and a weaker second. It is not more dye, it is sooner. **Extract versus raw.** A commercial extract may be five to twenty times the strength of the raw material, and the multiplier is the supplier's, not a constant. A recipe calling for 100% WOF of madder root means perhaps 10% WOF of madder extract, and that is a number to read off the packet rather than guess. Write down which form you used. A recipe that says only "madder 100%" cannot be repeated.

A dye day on 500 g of yarn is expensive in dyestuff, in fuel and in time. A dye day on five 10 g samples costs almost nothing and answers the same question. Work in jars standing in one pot of hot water. Each jar holds one sample at one concentration, all at the same temperature, all for the same time — so the only variable is the one being tested. Scale by WOF and the result transfers: a 10 g sample at 50% madder and a 500 g skein at 50% madder are the same recipe, provided the liquor ratio is kept roughly the same too. What does not transfer is evenness. A big pot heats and stirs differently from a jar, so a sample proves the colour and not the levelness. That is the dyebath rung's problem.