The difference between acrylic and wool

I just learnt how to tell the difference between acrylic and natural fibres like wool. This is important because you don't want to mix them together in one project, especially because they have different washing instructions.

my stash of 4 ply cotton

After finishing a rush of projects I had to finish by birthday deadlines, I did a stock take of all my yarns to decide what I would make next. I realised I still hadn't sorted all of my yarns into acrylic and wool, although my cotton is all separate. I've already made a couple of scrap rugs out of unidentified yarns, now I know that wasn't a good idea because some of it could be wool, while most is probably acrylic. I will have to wash those rugs as if it is all wool. I still had left a big bag of yarns that I assumed was acrylic, but I wasn't sure. How could I tell what was wool, and what wasn't?

I asked Google, and found on a site called Yarn Yak that one way to tell is to burn a small section of yarn. Here is the direct quote from that site "take a tiny snip of yarn, light it with a match. If it smells like burning hair, it's wool. If it smells like plastic, it's acrylic"

the reclaimed wool from a big pile of unidentified yarns

David and I couldn't tell the difference by just the smell of the yarn burning. We burnt lots of tiny sections of yarns that I knew were either acrylic or wool to learn the difference. What we found was the acrylics will melt, the ends becoming hard like melted plastic. The wools and cottons will ash, the burnt part falling away when you touched it. We blew on the burnt yarn to cool it then felt the end.

Burn a tiny section of unidentified yarn.

If the burnt end is hard and melted like plastic, it is acrylic. 

If the ash falls away, it is a natural fibre like wool.

Hoorah! I have now properly sorted my stash of yarns! Now ... what shall I make next???