Origami Diagramming Conventions: A Historical Perspective

those inevitable circumstances where both edges or both hooking arrows cannot be shown, the push
arrow can still indicate an outside reverse fold. However, the use of all four arrows simultaneously can
get pretty confusing. I would recommend either of the two combinations shown in figure 29, but not all
at the same time:
You’re crimping my style, man…
Figure 29. Two useful methods of indicating
an outside reverse fold.
Crimps and pleats are terms used to describe closely spaced parallel or nearly parallel creases.
Although there is some disagreement about what is a crimp versus what is a pleat, the most widely
accepted definition is: a pleat can be made by successive valley and mountain folds, while a crimp has
some reverse-fold action associated with it. In a pleated flap, all of the layers are folded together as one,
while in a crimp some of the layers go in opposite directions. These differences, and a few examples,
are illustrated below:
Figure 30a. A pleat.
Figure 30b. A crimp.
Figure 30c. More crimps.
Figures 30a and 30b are distinguishable by the arrangement of the layers, visible at the bottom of each
figure. However, when flattened so that the edges all coincide, they look exactly the same. I showed the
difference in my drawings by exaggerating the gaps between the raw edges. Quite often in origami
diagrams, one cannot easily show the raw edges to distinguish between a crimp and a pleat. If there are
more than two exposed edges, it is frequently impractical to show all of them. Fortunately, there is a
widely understood symbol used to indicate the configuration of the edges. We were introduced to it with
inside reverse folds: it is the edge view, which for crimps takes the form of a set of zigzag lines that
show the relative placement of the layers. An edge view clearly indicates the disposition of the edges, and
hence, whether a crimp or pleat is required.
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