Power Word Fold

Obsessive folders are renowned for folding any laminar material they can get their hands on – cloth, metal, icing sugar, and so on. Each of these materials has its own set of difficulties, as well as its own set of techniques for successful handling.

Plastics though, are one class of material that is notoriously hard to work with. Soft plastics don’t hold creases (that’s why they’re used as synthetic fabrics), while hard plastics tend to crack under stress (such as those produced when reversing a crease).

Cellulose acetate – the clear stuff used for overhead projector transparencies – is an interesting case. It’s capable of holding a crease without cracking, unless you try to reverse it, but it’s also extremely springy and smooth. Tension locking doesn’t work well as the smooth layers will tend to slide, causing your half-finished model to explode back into the original sheet.

Still, there are various tricks one can do to tame this beast. The first is one borrowed from sheet metal folding – since reversing creases is practically impossible, what one needs to do is to imprint the sense of the crease straight onto the sheet. This is easily done on plastic simply by scoring it – one side for the valley folds, the other side for the mountain folds. To do this, we’ll need a crease pattern showing the valley and mountain folds:


Guess what well-known design this is!

Solving the second problem – that of springiness – requires this little fact: cellulose acetate is a thermoplastic. Heat it up and it’ll become soft; let it cool and it’ll harden again. So, if we were to mechanically secure a bit of folded acetate (by means of clips, say), then heat it up in this folded configuration, we’d expect the folded acetate to be frozen in place once it cools down again. Which is what actually happens when you try it out – provided your heat source is just enough to cause the acetate to melt, but not burn. Sort of like wet folding really, but with a flame instead of water.



Gelatinous cube. Yum.