Yesterday while choosing yarn for the Mystery Stole, I attempted the bleach test (mentioned in the Yarn Harlot’s Knitting Rules on page 42) to verify the fiber content of some mystery yarn:
coned yarns
the pink is the 2-ply wool I’m using for the stole, the grey is a 4-ply dk/sport weight ??? and the white is a 3-ply fingering weight acrylic.

I wanted to be sure that the pink was indeed wool, for blocking reasons. (and I’m not sure if I want a pink stole, so dyeablility was also a concern). The grey. well, there’s a lot of it (compared to the rest of the cones that were in the box. thrift shop score from last year. these are the three fullest cones). The white, well, you never know if somehow the wrong label got attached or if they reused a cone or something, so I figured I’d verify it.

I dropped a small snippet of each of these, as well as another yarn that is known to be wool into a bit of bleach to see what would happen. when I came back an hour or so later, only one strand remained. the white acrylic. I did poke at the grey a bit before it disappeared - it seems the process is that the bleach attacks the color, and then it attacks the fiber. (the known wool also seemed to follow that process.)

I was bored (and entertained. my new guilty secret? I like torturing yarn.) so thought I’d document the process to save other knitters from any terrible accidents in the laundry room.

yarn torture part 1
I dropped a bit of the pink wool in around 1:50pm. this was taken at 1:51pm. the wool is the strand with all the bubbles around it. the other strand is the white acrylic that’d been sitting in the bleach for quite a while (before noon, I think) by this point.

2938.jpg
1:57:20 pm - I had poked at the yarn to see how things were progressing and it bunched up. it’s in the collection of bubbles at the bottom.

2940.jpg
1:57:44 pm - well, it would have been in that mass of bubbles. I pulled out the acrylic (you can see it hanging on the edge) and gave it a swirl. nothing left.

so there you have it. 2-ply laceweight wool in bleach = no yarn left after 8 minutes. lesson learned: keep the wool far far away from the bleach (unless you want to torture it.)

I suppose if you have a truly hideous piece of FUG made from natural fibers (the Harlot says this happens to silk and other animal fibers too), bleach would be a good way to destroy all evidence of it.