I made "brown" with reduced coffee and some cornstarch to make it more spreadable and I made "black" with the extra, extra salty liquorice I had lying around the house that nobody liked. Unfortunately I made both a bit too thick so they didn't spread too well and were a bit lumpy on the fabric but since I was going for large sections of colour it was ok
Once I'd "painted" it all on I left it for about 30 minutes and then rinsed it off in a sink full of water and vinegar to set the dye. Then I removed as much water as possible and then ironed it dry.
The white square you see is the starting colour and as you can see the black didn't really take so well and just became a pale grey. The brown is a bit darker but overall for an experiment with something I've never done before this was a decent result.
I will be using this for the 8 colour contest embroidery - I think it will give it just that bit more depth than plain cream fabric would do and will certainly show off the glow in the dark thread I'm planning on using.