Dried Buddleia Flower Dye - What Not To Do

I only started pruning back the buddleia in December - not entirely through neglect, I wanted enough long branches to make a structure for this year's Christmas Birdarium. The dried up flowerheads had stayed intact, adding considerably to the overall effect.

I was showing off photos of the Birdarium on Ravelry when a friend suggested using the buddleia flowers to make a dye bath. Though it seemed unlikely that these dessicated remains would have much dye in them, I checked out Jenny Dean's results.

Her bright yellows and greens persuaded me to get outdoors and finish pruning all the buddleia, despite pervasive freezing fog. The total weight of cold, damp seedheads came to about 600g. Crammed into a big pot, they were left to simmer while I took the dog out.

When I got back an hour or so later, the kitchen was a smelly sauna. The steaming pot didn't have an awful stink, just a powerfully plant-derived aroma with unfamiliar notes. Flinging open the back door, all those warnings about dyeing in a well-ventilated area came back to me rather too late. We usually live with the back door open and I hadn't even thought to put the extractor fan on. Hey ho, nobody died and when I sieved out the buddleia next day, the remaining bath did have a significant golden brown colour to it. Two 30g skeins of handspun Polwarth yarn, premordanted with 10% alum, had a gentle simmer and an overnight soak. After the wool had dried, the result of this 10 to 1 ratio of buddleia flower to fibre weight was a pale yellowish beige. Checking the pH, I found the bath was quite acid, but soaking a bit of the yarn in an alkaline solution made no difference to its depth or shade. Adding iron to the dyebath and briefly simmering one of the skeins again only modified its colour to pale greenish beige.

As I was downloading photos of these disappointing results, the computer made a strange new buzzing sound. A telephone icon popped up and one click revealed Elinor, waving gaily at me from the screen.
"Hiya, Beaut. Happy New Year!"
"Happy New Year, Elinor. Ooo, this is weird, seeing you just as if you were at home. Where are you really?"
"Still in London. We found this artisan bakery, perfect for all day breakfasts." The image on my computer wheeled round to show her friends, the Blewe Belles, packed round a wooden table, swigging tea and eating buns.
"They look happy."
"You don't. What's the matter, 2017 not treating you well?"
"Oh, I dyed yarn beige again. Overheated the dye bath, that might have destroyed the dye molecules and anyway, it was probably far too late in the season to be harvesting buddleia. Hope it isn't going to be a beige year."
Elinor frowned.

"Beige? Wrong word and wrong attitude, Fran. Get with the times. Beauty is all in the eye and the ear of the hipster." 
Elinor started footling about with the phone and my view was obscured by her hoof. "Call it sepia yarn, Beaut. Call it honest, real and retro. Here in the capital, taupe, tea and biscuit are old school authentic. Hold on, I'm sending you one of the latest shots from our portfolio."