My apologies - it was the spin cycle on my washing machine. For yes, the felting experiment continues.
After the interesting felting experiment with my little bag kit - now a repository for an unfinished pompom giraffe and monkey kit - I was left with three questions:
(a) what made that funny colour change half way through the second side of my bag;
(b) what gauge gives me the kind of felt that I want (ie not rock solid); and
(c) what temperature and program is best for felting in my washing machine given that I'm in the UK which means it's a front loading washing machine.
Happily there were some sizeable odds and ends left over from the felted bag kit with which to play.
Anna suggested the first option to explain the colour change - given that the purple was a single ply yarn was it possible that I had knit one ball with the twist going one way, and the other with the twist in the opposite direction which had given different colour reflections, and that distinct change when the light hit?
It's a good idea and certainly something to remember to check if I ever knit a garment from single plied yarn because the balls, even within the same dye lot aren't necessarily wound with the twist the same way.
I knit one square from the outside of the remaining ball and another from the inside. And the result?
No discernible difference at all.
These squares were both knit on 12mm needles which gives a much more open and loose pre-felting fabric; far more like what I was expecting for a pre-felting fabric than the solid bulk of four strands of yarn over 12mm.
However, all was not lost - although the real answer was mostly serendipitous.
I swatched the Paris with the pale pink Freedom Spirit. And before my eyes, the answer appeared; Paris Mohair Sparkle is variegated. Not sufficiently variegated to be obvious from the outside of the ball in my kit, and when I was knitting with it, the ball was on the floor where I couldn't see the second colour emerge. The colour repeats are long and it was just coincidence (and a cracking red herring) that the colour shift happened at the start of my second ball.
If you look here that's a Ravelry stash photo of the same yarn in which the two colour variation is much more pronounced.
I'm pleased that I've found the reason for the colour shift, what I really don't understand is why Twilley's put that yarn in the kit when the repeats are too short to do stripy or subtly variegated (both of which would be cool) - it's a mystery!
Stage 2 involved far more technical analysis: 1 washing machine, 3 swatches.
The first load of laundry that I needed to do was a 40 degree 'Acrylics' wash - slightly longer program than my 60 degree fast wash, but obviously a lower temperature and I was starting with what I considered to be a more reasonable pre-wash gauge.
The result is a more flexible finished felt, although still with sufficient thickness that H asked whether I was planning on knitting 21st century chain mail.
Actually H's latest theory is that a dart would bounce off it - maybe I should put that one to the test? It has certainly shrunk considerably compared to the 'control' swatch.
Most of the stitch definition is gone and as you can see from the little loose strand, the yarn has gone from a very smooth soft singles yarn to being distinctly nubbly - the felt definitely has texture and I think it could make a good bag fabric, possibly when knit at a looser gauge originally.
The control swatch and the mohair went through the machine in the next load of laundry - my socks on a 40 degree wool wash. The temperature is the same, the program length is roughly the same, the result:
No felting at all on either - if anything the red swatch grew a bit. All hail the power of my wool wash cycle!
So I still have two unfelted samples so I think I'm going to try the 40 degree wash again with very restricted spinning and possibly the 30 degree wash on my usual spin setting and as H has a sports match this weekend there'll be no shortage of laundry!