On wool and blocking

I heart wool.

I do! It’s my favorite thing to knit with. Add a bit a silk and I’ll be drooling like Pavlov’s pooch. I feel really, really sorry for knitters allergic to wool. I know there are many other types of fibers out there to knit with, but really–nothing comes close to wool. Love love love.

I finished my mum’s birthday stole awhile back. Knit, of course, with wool. Blue Moon Fiber Arts Laci, to be exact. Anyway, I finally mailed it to her last week, and I got a very excited phone call last night. She got it. She loves it. She is amazed by it. In fact, she told me she’s going to wear it to work on Monday, which surprised me a bit since it’s kind of dressy. Well, let me show you a picture and let you judge for yourselves.

Okay, this picture is crappy. I had a had time capturing both the color and the lace pattern in the same photo. That one ^up there^ is the color. Here’s the lace pattern.

It never fails to astound me what beauty is contained in lace. And what astounds me even more is what it looked like beforehand. I was a bit worried about the length of this stole as I was knitting it–it was seeming really short, so I knit the required number of repeats, slipped it onto waste yarn, and blocked it. It turned out much longer than I thought it was going to, but it still wasn’t long enough. So I put it back on the needles and knit two and a half more repeats. Before I blocked it again, I snapped a pic.

Can you see the junction? It’s about halfway down. I don’t remember who originally coined the phrase “a big pile of ramen noodles” describing unblocked lace, but dang is that apt. Blocking is the magic wand that makes it all pretty, bippity boppity boo and you’re ready for the ball.

So yeah, we all know that wool does, in fact, block, but have you ever asked yourself why wool blocks? Well, I have. So I looked it up. More or less, here’s the answer.

So, wool is made up of protein fibers, right? Right. Just like our hair. And proteins are made up of strings of amino acids. Amino acids are called the building blocks of life. There are twenty of them. Here is a list, in case you’re interested. So these strings of amino acids are known as the primary structure. Proteins have a secondary structure too, which is how the strings of amino acids interact with each other. The particular secondary structure that wool proteins adopt is called a beta-sheet (not to be confused with a dryer sheet). And it looks like so:

So all of those strings of Ns and Cs and Os running up and down the image are the amino acid chains (the primary structure). They are connected by solid lines–that means chemical bonds. The dotted lines you see going across the page between the Hs and Os are called hydrogen bonds. They are not the same as real bonds–they’re a kind of electrostatic interaction. You can think of it as adjacent molecules kind of holding hands. (Awww! They like each other!) This hand holding between strands makes up the secondary structure, which helps hold the protein together and lets wool keep its shape.

Another thing that helps wool keeps its shape is the tertiary structure. As you can probably imagine by the name, tertiary structure is one step beyond the secondary structure, and is the spatial arrangement of amino acids that are far apart in the chains. Here’s an example.

So the snaking line there is the amino acid chain. S means sulfur, and the S-S things between the chains are known as the disulfide linkages. So if hydrogen bonding is hand holding, disulfide linkages are more like a double arm grasping–you know, like how trapeze artists hang onto each other when they’re swinging around? Disulfide linkages are stronger than just a hand-holding. And these make up the tertiary structure, and again help hold together the proteins.

So what does all this crap have to do with blocking? Well, when you plunge your finished knitting into a basin of water, all of the hand holding and arm grasping lets go. Since there’s so much of it around, the amino acids grab onto water molecules instead of their neighbors and friends. (As an aside, ever wonder why wet wool smells so stinky? It’s those breaking sulfur bonds. Sulfur smells like ass.) As you can imagine, this weakens the structure of the wool, which means you should always be careful when handling wet wool. It can break! But it’s also good, because it means that we can sculpt our finished knitting into the shape that we want it to take. And as the wet wool dries, the water molecules evaporate into the atmosphere, taking away their hands. So then the amino acids in the wool have to grab onto their friends and neighbors again, locking the new shape in. And hence we get beautiful knitted lace, instead of ramen noodles.

Pretty amazing, really.

Okay so, I presume you want to know the details of the stole. Here ya go.

Pattern: Japanese Feather Stole, by Anne Hanson of knitspot
Yarn: Blue Moon Fiber Arts Laci in Tlingit, a bit less than one half skein (appox 800 yds)
Needle: KP Options, US 6
Started: March 17
Finished:April 19 (the day after mum’s birthday–oh well)
Mods: Knit with smaller yarn (laceweight instead of fingering) on smaller needles, did 13.5 repeats instead of 11.
For: mumsie, on her 60th birthday. With love from chemgrrl.

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And like a good scientist, I must cite my sources. I had help from:

Stryer, Lubert. Biochemistry; Fourth edition; W.H. Freeman and Company: New York, NY, 1998.
Bradbury, J.H. Pure & Appl. Chem. Vol 46. pp. 247-253. Pergamon Press, 1976.
Lindley, H. Chem. of Nat. Protein Fibers. pp. 147-191. Plenum Press, 1977. (images came from this paper)