I recently dyed a range of yarns, some cotton, and my recently completed knitted socks, with turmeric.
In preparation, I tied the loops of yarns in a number of places, and then soaked the yarn, fabric and socks in cold water so that they would take the dye better.
I made a paste with a full jar of ground turmeric from the supermarket (approx 45g), and placed this and my yarn and cotton in a large stainless steel pot with enough water to cover everything.
I heated the pan on the hob on a low temperature for one hour. As I was more cautious about my socks I added these for the last 30 minutes only.
I did stir the pan occasionally to try and ensure the colour would be even, but didn’t stir excessively as I was wary about the wool items felting.
After an hour I turned off the heat, but left the items in the pan for another couple of hours, after which I rinsed the items with a mild wool wash, and left them to dry.
The yarns I started with were all white or off-white. The yarns used (shown from left to right below) were:
♥ 40% Polyester, 33% Acrylic, 27% Cotton, containing glitter and sequins (Sirdar Soukie DK, in Gold Dust)
♥ 100% cotton (Rowan handknit cotton)
♥ 75% merino / 20% silk / 5% cashmere DK (Sublime)
♥ 100% wool DK (TOFT Alpaca, in Oatmeal)
♥ 100% merino wool chunky (Rowan Big Wool)
You can see the range of yellows I achieved below. The cotton fabric and yarn (on the left) are the lightest, the synthetic yarn (top) and merino/silk/cashmere blend (centre) are a medium shade, and the 100% wool yarns and socks achieved the darkest shades.
Turmeric is a substantive dye, so I dyed these without mordanting my yarn / fabric. However, turmeric is reported to fade easily, so if you’re dyeing something that you plan to wash, it would be best to mordant. I wasn’t concerned because I’m planning to use the yarn in a weaving, and if the colour of the socks fades I’ll redye them.