I've been veeeeery gradually getting back to spinning, and noticed the other day that I had a fine example of what pre-drafting is, why you do it, and what it's good for.
For our discussion right now, I'm going to call pre-drafting everything you do between taking the fiber out of the sales bag when you get it home, and actually drawing it out into a ply at the spinning wheel or spindle. In a way it covers a lot of ground, but in a way it's all the same thing. For anyone who's curious, my entire (usual) spinning process is described in more depth, HERE.
In discussions around the 'net and in classes and elsewhere, it seems like pre-drafting is THE mythical skill, like heel-turning or steek-cutting is in knitting. People who aren't experienced are intimidated by it, people who HAVE done it are blase and dismiss it as a non-skill.
In short, what pre-drafting does is this: Whatever it takes to get the fiber loose enough to be drafted easily at the wheel. You want to fight and curse and get sore hands and shoulders, you don't have to pre-draft at all. But for a nice smooth spin (and I think since we're hobby spinners, enjoyment should be a goal), the fiber needs fluffed a bit, or unstuck. How you do it doesn't really matter, so long as there's no destruction of property.
Here, have a photo of what I'm talking about.
What I did was divided the pencil roving lengthwise. (It was so easy, I think the roving was doubled for the dye process, to begin with.) Then, the ball on the left, I went through and every four inches or so, gripped the roving and lightly pulled it apart. It's sort of like a half-draft: It's exactly the same pull-to-make-thinner that I do at the wheel, but not as drastically, and without any twist being added. The other popular way to fluff the fibers is to pull laterally and spread the fibers out that way - basically the opposite direction of this method. Dividing top lengthwise repeatedly is often enough to fluff out the the fibers all on its own, and it is the other method I use for this.
You can see, even if you don't spin, that this loosened the fibers quite a lot. I have since started spinning the pre-drafted fiber and it's drafting smoothly. Awesome.
Here's a more extreme example:
That's what pre-drafting is for. That's the only point. However you do it doesn't matter. There's no wrong way.
Now, for my next trick, I'm gonna turn a sock heel. Or maybe steek the cat. (Not really. Still knitting the third half-a-washcloth shawl.)