WOF - Weight of fibre
All measures in dyeing are based on the weight of material to be dyed. This is known as the Weight Of Fibre (WOF). WOF gives a convenient way to state how much dyestuff is needed for a given shade, regardless of whether the dyer wants to colour a few yarns or several metres of fabric. The weight of dyestuff is expressed as a percentage of WOF.
For example:
To dye a medium-red with madder, we would use 50% WOF. Hence, if we had a pound of cotton, we would need a half-pound of madder.
Weight of Fibre (dry) x % = Weight of Dyestuff (dry).
50% WOF madder — (metric) 450g x .5 = 225g. Use 225g of dyestuff to dye 450g of fibre.
50% WOF madder — (imperial) 1lb x .5 = .5lb. Use half a pound of dyestuff to dye a pound of fibre.
Alternatively, cochineal bugs only require 5% WOF for a deep shade. Hence, to dye the same amount of fibre we would need:
5% WOF cochineal — (metric) 450g x .05 = 22.5g. Use 22.5g of dyestuff to dye 450g of fibre.
5% WOF cochineal — (imperial) 1lb x .05 = .05lb. Use .05lb of dyestuff to dye a pound of fibre.
Yarns, fibres, and fabrics are always
weighed dry before scouring.
Tip: Keeping notes of the weight of fibre and how much dyestuff was used will help plan future projects - clipping a sample of dyed yarn beside the notes makes for a wonderful record.
See our free lesson on Weight of Fibre (WOF) at the Maiwa School of Textiles