Valley fold

(This page is part of the origami tech tree. Currently, this page is a first try at text instructions for making the origami valley fold. This page needs pictures (and maybe an animation).)

Most origami folds can be broken down into simpler steps. Even the valley fold -- which most people do as "just fold the paper in half" -- is really made of substeps. These steps help fold the paper very precisely, which is important in complicated models. Here is one way to make the valley fold very precisely:

1. Loosely fold, without making a crease.
2. Line up edges.
3. Line up a corner (by lining up the edges on one side, and lining up the edges on the other side).
4. Hold (a loosely folded, uncreased) paper down to prevent slipping.
5. While holding the paper down so it does not slip, spread out a flat area on the paper. This is often done by holding the paper down at two edges with your index fingers. Also hold down the paper with one (or both) thumbs. Gradually move your thumb(s) away from your finger(s), pushing your thumb into the paper, but pulling the paper taut between your thumb(s) and your fingers.
6. Pinch a crease. While holding the paper down so it does not slip, spread your thumb(s) far enough from the edge that they reach the intended crease line.
7. Resolve a crease. Without letting up on the paper, continue the spreading motion until the crease is sharp. The crease should be exactly where you intended it to be, without any wayiness in the edge, without any "bubbles" in the layers of paper, and without any slipping of the paper at the edge(s) or corner(s).