Spiral binding: coil through punched holes

• One continuous coil, an unbroken strand of plastic or metal, threads through every punched hole along the edge.
• Hole shape varies by manufacturer's die: both round and oval punches show up in commercial spiral binding.
• There's no limit on how far it opens: the two covers can keep rotating past flat until they land back to back around the coil.
• Next to comb or Wire-O, look for the coil: one strand runs through the whole row at once, unlike comb's separate molded ring or the paired loops Wire-O closes hole by hole.

Can a spiral-bound notebook really fold all the way back on itself?

Yes. Every page rotates independently around the same continuous coil, so there's nothing stopping the front and back covers from meeting behind the book, unlike a bound spine that has to flex as one piece. Walsworth's guide describes this as 360 degrees of mobility, and it holds regardless of hole shape or coil pitch, since the coil itself is what lets each page spin freely rather than any one manufacturer's specific hardware.

Does the coil come loose over time?

It isn't supposed to. The same mybinding guide says the coil is cut and crimped at both ends specifically so it can't unwind, and that crimped closure, not glue or tape, is what holds a spiral-bound book together at the spine.

Does spiral binding lay flat?

Yes. Every page threads onto the same continuous coil and rotates freely around it, so nothing holds the book back from lying flat once it's open. That same rotation lets the two covers keep going past flat until they meet back to back around the coil, which is why a spiral notebook folds all the way over instead of settling at a fixed angle the way a glued spine does. See which bindings open flat.

Is spiral binding the same as coil binding?

Yes. Mybinding's own guide opens by calling coil binding 'also known as spiral binding,' describing one method: a single continuous strand of plastic or metal threaded through a row of punched holes along one edge. Plastic coil is a third name for the same thing, and neither name points to different hardware or a different way the pages rotate around it once it's threaded through.

What is the difference between Wire-O and spiral binding?

The two use different hardware for a similar-looking job. Spiral binding threads one continuous coil through every punched hole in a single unbroken helix, while Wire-O closes a pair of C-shaped loops through each hole individually, so the spine reads as a row of tight double loops instead of one strand. Both let pages rotate fully and let the book fold flat, but Wire-O closes its paired loops hole by hole, while spiral runs as one continuous piece from end to end.

Who invented spiral (coil) binding?

No single inventor is named in the sources here. Wikipedia's account of coil binding names the earliest company instead: the Spiral Binding Company, founded in 1932 and described there as the first mechanical binding company in the United States. That's a history of the coil hardware itself, a continuous strand threaded through punched holes, not of the word 'spiral,' which just describes the shape the strand takes once it's threaded through.