Madder Root Dye with Alum, Rhubarb and Iron as Mordants on Wool

"Perhaps I could mordant six small skeins of yarn, two of each with alum, iron and rhubarb, dissolve the calcium carbonate a day in advance, get hold of some real bran instead of using porridge oats, give the madder roots a boiling water rinse before chopping them up, then divide them into two dye baths and process one by heating to 80 degrees Centigrade and keep the other at room temperature for a week. Then I could compare the results and find out which works best, hot or cold madder dyeing. Only the cold bath would ferment over time and get more acidic than the hot one and that would affect the dye colours. I could keep adjusting it every day - what pH do you think I should aim for?"
I looked at my companion, Elinor Gotland, who got up from her chair.
"Madder, madder, bloody madder. It's all you think about."
"Exactly. I mean, I'd love bloody madder." I called after her retreating back. "You might be a bit more supportive. You'll see, when I've decided how best to optimise all the variables, I will get blood red out of these madder roots."
Elinor turned and blew me a theatrical kiss.
"Why not keep it simple, sweetie?"

Three 50g skeins of wool yarn were mordanted, one with 10% alum, one with 2% iron and the third was simmered with three rhubarb leaves to soak up some oxalic acid.
An equal weight of 150g dried madder root was chopped up in the kitchen blender, boiling water was poured over it and the pot was left to steep overnight. 


Next day, I added the three skeins, heated the pot until it was properly hot but not boiling, kept it hot for an hour and allowed it to cool overnight. No rinsing the roots beforehand and no additives at all, not even soda ash to raise the pH of the dye, which proved to be naturally mildly acidic when tested with indicator paper. 

Here are the results, fresh from the dye pot. The alum mordanted yarn, which was Blue Faced Leicester wool, had turned the truest red I have achieved with madder in ages. The rhubarb mordanted yarn was far more orange and the iron mordanted yarn was milk chocolate brown. I've read that alkaline modification can turn that brown to aubergine, so the iron mordanted skein had a soak in warm water with a teaspoon of soda ash before being hung up to dry.

"The brown one hasn't really gone quite purple enough to be called aubergine, but I'm astonished and so pleased with these colours. Particularly the red. Wish I'd used ordinary old alum mordant on all three skeins. I'd never have believed that you could get a good red from just madder roots and water."
I turned to my companion and to do her credit, detected no trace of smugness in her expression. She shrugged.
"Less is more, Beaut."

I put 100g of my finest alum mordanted Falklands Merino and Tussah silk blend 4ply yarn into the madder root bath and heated it up again next day. Even the afterbath gave a truer red than I have become accustomed to. Maybe I'll find I can't replicate the conditions and do as well every time, but it's tremendously heartening to get a win when you least expect it.