Shortly after learning to weave, I became interested in weaving with Tencel. Tencel (the generic name is lyocell) is a man-made fibre made from wood pulp cellulose in a process considered environmentally friendly because plantation or sustainable managed timber is used along with a non-toxic solvent that is fully recycled. It is stronger than cotton and has a much nicer feel to it than Rayon (another man-made cellulose fibre). The fibre is fully biodegradable.
Obtaining undyed Tencel is much cheaper than mill-dyed Tencel, so it became attractive for me to try dyeing some of it myself. I had previously dyed wool, but as wool is a protein fibre, it used different dye chemicals to cellulose. I went in search of instructions on the internet and found information – some of it on cellulose fibre dyeing in general and some of it on Tencel dyeing specifically. The best choice of dye was fairly clear – Procion MX type dyes. But I had difficulty working out just how much dye to use, not helped by having to convert from pounds to grams of fibre (as most information is American), and just how much dye is in a teaspoon?
One of the biggest problems I’ve had in dyeing Tencel has been in achieving the desired colour and depth of shade. What I didn’t really comprehend until I actually tried it was that Tencel requires much less dye than cotton (compare the cotton tie on the Tencel warp in the picture on the right – the cotton is more pink than the Tencel’s red). To compound the problem, the patent on “Procion MX” has expired, so each supplier now has its own generic version (hence “Procion MX type” dye). And colour ranges seem to vary greatly depending on the supplier. So even with a guide to how much dye to use, it’s still a guessing game as one supplier’s dye might not behave exactly the same way as another’s.
The other thing that bothered me was that I could not get dye bath exhaustion – something that was normal in wool dyeing, and lots of dye appeared to come out in rinsing. When I’d bought my dye the shop assistant even said “it exhausts really well”. Not for me it wouldn’t, at least not on Tencel. After much research I found that this is actually normal reactive dyeing behaviour of Tencel (for the technical minded: Taylor, J. (1999). The reactive dyeing behaviour of Tencel [link removed - broken] . JDSC Vol. 115 pp. 294-296. See particularly Figure 1.). At the end of dyeing, about 80% of the dye used will be fixed to the fibre, 10% will be in the fibre but not fixed (and needs rinsing out) and 10% will remain in the dye bath.
Mixing colours has also been quite unpredictable. I quickly found my “black” appears to be blue at low concentrations and more greenish at middle concentrations. So I won’t be using that dye any time soon to get grey yarn! I mixed blue and red and ended up with a murky greyish purple. I finally got a very nice purple from mixing violet and blue. So far I suspect my blue dye is very dominating and has to be used in very small proportions, and maybe something in the red is reacting with other colours to create muddiness. Only more experimentation will reveal the answer!
And the most important thing is – keep records! – or you’ll never be able to reproduce colours or adjust dye concentrations to get what you want.
Here are my dyeing methods, generalised for all cellulose fibres, but with some suggested dye amounts for Tencel:
Introduction – Safety, equipment, yarn preparation and auxiliary chemical sourcing notes. Please do read this first.