What a stunning yellow! I love that you shared your technique. Natural dyeing is such a wonderful thing and sharing knowledge is important. I've started doing a bit of experimenting with natural dyes recently and have enjoyed the result (just willy nilly stuff...without any mordant). It seems that most people use alum...I'm going to have to try that!I did get a lovely light purple from some purple iris blossoms by just throwing some cotton in the jar! And, frankly, I just kept the jar in the fridge for it to soak.
I was really surprised by the rich yellow hue! I learned to dye from other people who were willing to share the information and I agree with you, we're all in this together! Alum is the safest mordant to use, which I think is why it is so popular. I might have to try that with my irises next year! Haven't tried dyeing with cotton yet, but I would like to try. Good luck!