Madder on wool/cotton

I've been looking forward to trying madder for a long time, for a few reasons. I love reds, pinks and burgundies. I like that the root doesn't look remotely red before extraction, so it's one of those magical dyes that doesn't do what you expect. I love its name, because it means 'more mad', and because it reminds me of Madder Rose, an alternative rock band who played Reading in 1993, when I was at the peak of my festival-attendin', NME-readin', grunge-lovin' ways. And I like that it's one of two dyes - alongside indigo - of which people might have heard, or at least might understand when you tell them that it's used to dye the 'pink' (i.e. red) hunting jackets.

I bought four skeins of Rowan wool/cotton (50% of each), which is a lovely, soft, warm yarn. My intention is to dye each skein a different shade of red/pink and then to knit a pair of striped armwarmers using the four shades. In this dyeing session, I attempted two of the four skeins, using iron on one of them to vary the results.

I'd heard that madder works best if you grind it finely, soak it for up to a week before use and extract it several times. I ignored all of this advice because I am (a) lazy and (b) happy to end up with subtle shades.

Fabric: 100g wool/cotton (50% wool, 50% cotton)
Dyestuff: 50g (50%) madder chips
Mordant: 2g (2%) copper (copper sulphate) with 10ml white wine vinegar (10ml vinegar is approximately equal to 2ml acetic acid. You can use less copper sulphate - 2% rather than 20% - if you use 2% acetic acid as well. I only read about this recently, otherwise I'd have done it last time)
Colour modifier: 3g (6%) iron (ferrous sulphate) used on only one of the hanks

I tied my hanks with green cotton. The acidic mordant bath made the white yarn slightly green, and turned the green yarn orange. How peculiar.



After five minutes in the bath, the yarn's colour was disappointingly subtle.



But the colour deepened and developed, just very slowly. After two hours in the bath, it was much more pronounced.



Curiously, sprinkling the iron in didn't plunge the bath into blackness as it usually does. Instead, the bath went from a clear red to a cloudy orange/brown. I gave one hank 20 minutes in the iron-modified bath and then rinsed the hanks. Very little extra dye came out of the yarn.



I think these colours are rather lovely. I would describe the copper-only ball (on the right) as a dusky rose; the copper/iron ball (left) is beige with a touch of lavender. They're very subtle, though, which I'm sure is to do with my failure to prepare the madder properly before dyeing.

What isn't subtle at all is what the acidic mordant bath did to my ties:



I'm very surprised by this. The yarn was boiled up in about three litres of water with just two teaspoons of vinegar and this was the result. True, there was copper sulphate present too, but I've never seen a mordant do this kind of thing before, so it seems likely that the vinegar is responsible. I didn't know that vinegar had amazing colour-changing powers! It's like those felt-tips you had at school that came with a magical white pen to change all the colours. It makes me want to start boiling all of my clothes up with vinegar to see what happens.

I think I will dye the remaining two hanks with madder again, but next time I'll prepare the dyestuff more thoroughly and I'll use alum as mordant. With a bit of luck, I'll get more intense red/pink shades, which should give me four lovely stripes for my armwarmers.