Wet-folding is an origami technique developed by Akira Yoshizawa that employs water to dampen the paper so that it can be manipulated more easily. This process adds an element of sculpture to origami, which is otherwise purely geometric. Wet-folding is used very often by professional folders for non-geometric origami, such as animals. Wet-folders usually employ thicker paper than would usually be used for normal origami, to ensure that the paper does not tear.
One of the most prominent users of the wet-folding technique was Éric Joisel, who specialized in animals, people, and mythological creatures such as fairies. He also created origami masks. Other folders who practice this technique are Robert J. Lang and John Montroll.
The process of wet-folding allows a folder to preserve a curved shape more easily. It also reduces the number of wrinkles substantially. Wet-folding allows for increased rigidity and structure due to a process called sizing. Sizing is a water-soluble adhesive, usually methylcellulose or methyl acetate that may be added during the manufacture of the paper. As the paper dries, the chemical bonds the fibers of the paper tighter together which results in a crisper and stronger sheet. In order to moisten the paper, an artist typically wipes the sheet with a dampened cloth. The amount of moisture added to the paper is crucial, because too little will cause the paper to dry quickly and spring back into its original position before the folding is complete, but too much will fray the edges of the paper or will cause the paper to split at high-stress points.
Click the imageEric JoiselClick the image
Modular Origami
Modular origami or unit origami is a paperfolding technique which uses two or more sheets of paper to create a larger and more complex structure than would be possible using single-piece origami techniques. Each individual sheet of paper is folded into a module, or unit, and then modules are assembled into an integrated flat shape or three-dimensional structure by inserting flaps into pockets created by the folding process. These insertions create tension or friction that holds the model together.
Modular origami can be classified as a sub-set of multi-piece origami, since the rule of restriction to one sheet of paper is abandoned. However, all the other rules of origami still apply, so the use of glue, thread, or any other fastening that is not a part of the sheet of paper is not generally acceptable in modular origami.
The additional restrictions that distinguish modular origami from other forms of multi-piece origami are using many identical copies of any folded unit, and linking them together in a symmetrical or repeating fashion to complete the model. There is a common misconception that treats all multi-piece origami as modular, but this is not the case. More than one type of module can still be used. Typically this means using separate linking units hidden from sight to hold parts of the construction together. Any other usage is generally frowned upon.
Click the imageMathematics of Modular OrigamiClick the image
Action Origami
Action origami is origami that can be animated. The original traditional action model is the flapping bird. Typically models where the final assembly involves some special action, for instance blowing up a waterbomb, are also classed as action origami. More rarely models like paper plane and spinners which have no moving parts are included. Some traditional action origami involved cuts but modern models typically are built with no cuts. Action origami are normally toys built to amuse but some are designed to inspire wonder.
Action toys include birds or butterflies with flapping wings, beaks that peck, and frogs that hop, as well as popular traditional models like the fortune teller. Paper poppers or bangers are models that make a noise when flicked down hard.
Flashers are models with a regular pattern that can be folded up small and rapidly expanded. The Miura Fold is a similar idea that has been used in commercial applications. Versions on a regular pattern can for instance be used to make a human figure when folded up or a maze when opened.
Click the imageMiura Action FoldClick the image
Pureland Origami
Pure Origami is a relatively new invention. Making paper creations with folding and cutting was common in the past. The 200 year old book Senbazuru Orikata shows models where cuts have been made. There's no apology or "oops" involved, it was okay to have cuts. Even today, some Japanese origami books will have models that have cuts.
In the late 1970's, John Smith developed the concept of "Pureland" origami. The rules in Pureland origami are the same as those for pure origami with the added restriction that only mountain and valley folds are allowed. The "land" part of Pureland comes from the fact that mountain and valley are elements of land.
In a zen sort of way, Pureland brings people away from the complexity and back to the simplier times and ways of life.
