Natural Dyes - Weight of Fibre

by - Thursday, November 25, 2010

The Maiwa Guide to Natural Dyes
What they are and how to use them

Weight of Fibre.
This straightforward concept is important enough to deserve its own post.

All measures in dyeing are based on the dry 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 (450 g) we would need a half-pound (225 g) of madder.

Weight of Fibre x % = Weight of Dyestuff

(imperial) 1lb x .5 = .5lb (8 oz)
(metric) 450g x .5 = 225 g

Alternatively, cochineal only requires 6% WOF for a medium shade.
Hence, to dye the same amount of fibre we would need:

Weight of Fibre x % = Weight of Dyestuff
(imperial) 1lb x .06 = .06lb (1 oz)
(metric) 450g x .06 = 27 g

Yarns, fibres, and fabrics are always weighed dry before washing. But everything is wetted before being placed in the dyepot.

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. This is one portion of dyeing that we love. Making books with notes, samples, and recipes is a creative act in itself. Of course, if someone discovers your books one hundred years from now, thats also very exciting.

The Maiwa Guide to Natural Dyes

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  1. Should fibers be weighed for dyeing before scouring? I am hoping to scour a large amount of fibers in one day so they are ready for mordanting and dyeing throughout a season. I imagine the weight will change from pre to post scouring, and I'm not sure which weight I should use for my WOF. (I would be drying the scoured fibers before weighing, as I know the WOF is for dry fiber.) Thanks so much for your help!


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