Origami Heaven

A paperfolding paradise

The website of writer and paperfolding designer David Mitchell

 A Technical Analysis of Origami Design

 This page attempts a broad analysis of origami design, in terms of the factors that distinguish one design from another from a technical viewpoint, in the form of a family tree,The links within the text lead to pages that provide more detailed information about some of the branches.

 1 Fundamental style is about whether the design is folded from a single sheet of paper or from several, perhaps many.Single sheet origami is origami folded using only a single sheet of paper, irrespective of size or shape. Slit sheet origami is origami is origami using a single sheet which has been slit to partly separate it into multiple sheets. Slit sheet origami is a half way house between single and multiple sheet origami. Multiple sheet origami is origami folded using two or more sheets, irrespective of size or shape, which are combined, in any way, to create the finished design. Modular origami is a sub-set of multiple sheet origami in which two or more sheets are first folded into modules, which need not be identical, then integrated to create a stable geometric design without the use of glue or any other form of adhesive. Macromodular origami is a development of modular origami in which complete modular assemblies (macromodules) are combined into integrated second-generation structures either just by themselves or with the addition of extra modules to act as separating or joining pieces. More detailed information about modular and macromodular origami can be found on the Modular and Macromodular Origami - Definitions and Notes page. 2 Origami designs can be folded from any starting shape of paper. Most commonly the starting shape is a square but it can also be any other rectangle, including a long strip, triangle, or any other polygon, whether regular or irregular. Some paperfolders have ethical objections to the use of irregular or concave shapes or an ethical preference for using particular rectangles, notably the square. Primary folding geometry is related to paper shape. 3 There are two fundamentally different types of paper used for origami, homogeneous paper and differentiated paper.By homogeneous paper I mean paper that is the same colour and pattern on its two surfaces. By differentiated paper I mean paper that is a different colour or pattern on its two surfaces. I call differentiated paper that is a plain colour one side and white on the other 'irogami'. Duo paper is paper that is a different plain colour on each surface. It is, of course, possible to have patterned irogami and patterned duo as well. Irogami or duo paper can be used to create contrast patterns on the surface of a design. 4 There are three distinct kinds of folding geometry, primary folding geometry, secondary folding geometry and embedded secondary folding geometry.An explanation of the meaning of these terms together with a discussion of the most used angular systems can be found on the Folding Geometries and Angular Systems page. The secondary folding geometry of origami designs can also be derived from the division of the length, or the length and width, of a paper shape, usually a square or a rectangle, into thirds or fifths. Similarly, designs can be based on the divison of a right angle corner into three or five equal divisions. Examples of designs of this kind can be found on the Designs based on division into thirds and fifths page. A hybrid design is a design that makes use of more than one folding geometry. 5 Folding style is about how the folds within a design are made. A fold is a change of direction in the plane of the paper.Traditionally, paper was always folded dry, and most origami designs are still folded in this way. Dry folded designs are characterised by sharp creases and largely flat surfaces between the creases, although dry folds can also be used to create induced curves and action designs in which one part of the finished design moves in relation to another when parts of the design are stretched or compressed. Dry folds may be either uncreased, softly creased, or sharply creased. If you take a sheet of paper by two opposite edges and bend it into a curve you have made an uncreased fold. If you take a sheet, lay it on a flat surface then push two opposite edges gently together it will rise up into a dome. In doing this you have made three uncreased folds, two in one direction and a third, at thye top, in the other. It is not always easy to count uncreased folds in a complicated structure. A creased fold is made by flattening an uncreased fold so that two, or more, layers of the paper lie on top of each other. A softly creased fold is one where the fold line is flattened but not completely flattened so that the fibres lying across the fold line are not broken. A sharply creased fold is one where the fold line is completely flattened so that the fibres lying across the fold line are broken and a permanent line of weakness is created. Folds of different kinds can be combined within the same design. Some papers lend themselves to the making of one type of crease better than another. Wet folding (a misnomer since the paper is folded slightly damp rather than wet) was an invention of the Japanese paperfolder Akira Yoshizawa who was looking to create folds of natural subjects which were as realistic as possible. Damp paper folds without taking a crease and the resulting soft folds are set in position when the design dries. The paper may stretch during the folding process so that unlike a dry folded design a wet folded one cannot necessarily be unfolded to a flat sheet again. It is possible to combine wet and dry folds within a single design. Crumpling is a dry folding technique in which the paper is repeatedly crumpled up to create a random pattern of small intersecting sharp creases. These creases turn a flat, non-stretchy sheet of paper into a non-flat, stretchy one. The crumpled sheet can then be manipulated into forms which are much more organic than those possible with other dry folding techniques. 6 Ethical considerations are those restrictions which designers and folders choose to impose upon themselves which limit the techniques they are willing to employ to create a design.Examples might be: Only folding from squares Not being willing to use cuts Not being willing to use adhesives to hold disparate parts of the design together Not being willing to use paper which has been decorated in some special way to make disparate areas of the design stand out from each other. Not being willing to decorate, draw details on or glue googly eyes to, the finished design.