I dye yarns and fibres with indigo. This ancient process produces fabulously varied shades of blue and I like to exploit these by tie dyeing and dip dyeing the yarns as well as producing semi-solid shades.
While indigo produces wondrous shade variations, I realise not everyone wants to dress from head to toe in blue. So I dye or overdye some of the yarns with acid dyes which increases the colour range; more interestingly, underlying indigo gives a depth and range of effects to each skein.
WHAT IS INDIGO?
Indigo is an ancient dye; it has been used since at least 2500 BC. Most continents have native plants that produce indigo. It is a sustainable dye; after the pigment has been extracted the plant residue is composted and the water reused to irrigate crops.
Most natural indigo dye for sale comes from the leaves of Indigofera tinctoria which grows best in the tropics, thriving in heat and humidity.
Indigo is light-fast and, unlike most natural dyes, does not need mordanted first.
Synthetic indigo is widely used nowadays, not only by huge denim mills but by many artisans worldwide in order to produce reliable results. It is chemically identical to natural indigo and bonds in the same manner.
Indigo does not chemically bond to fibre, but creates a physical bond, expanding when exposed to oxygen and getting trapped within the fibre.
Blue hands are a normal feature of using indigo. All my yarns and fibres are well rinsed and dried but when you manipulate the indigo-dyed yarn (winding it and knitting with it) the last loose particles of dye are released. As the fibres are being handled they rub off on your hands. This is not a flaw. These large indigo particles cannot bond to lighter coloured fibres as you work - they are too large and will simply wash away.
Any excess blue on your hands or clothing can be removed with water and soap but it can stain bamboo and wooden needles indelibly.