Many people have developed wet-folding techniques. These are some that I’ve found useful.
The paper is the first consideration. Most paper contains a material called sizing, a water-soluble adhesive that binds the fibers of the paper together and adds stiffness. Sizing is the secret of wet-folding. When the paper is wet, the sizing dissolves and releases the fibers, making the paper soft and floppy. When it dries, the sizing holds the fibers in the shape they were in when they dried.
Thus, a good wet-folding paper contains a lot of sizing. One of the best is “calligraphy parchment,” which contains so much that your hands become sticky while folding it. Almost any paper will work, however, and watercolor paper, because of the range of colors and weight and its availability, is a good all-around paper.
The paper must not be glazed, however, or water will stand on the surface and/or soak in unevenly, resulting in rippling. It also must not be too thin or there won’t be enough fiber for the paper to support itself. A good paper to use for larger models (e.g., 50 cm square) is 160 gm/m2 watercolor paper; thinner papers work better for smaller models.
You should dampen the paper before you cut your square from it. It is easy to do this evenly with an atomizer that can spray a fine mist, but simply wiping the paper with a damp cloth will work too. Both sides should be dampened equally. The trickiest part of wet-folding is getting (and keeping) the paper at the right consistency; it should be neither stiff nor soaked, but of a leathery texture. if there are shiny patches of wetness it is too wet and you should leave it to dry a bit. The same applies if the creases begin to get “fuzzy”.
With the paper thoroughly and evenly damp, you may cut your square and begin folding. Naturally, the paper will begin to dry almost immediately. You deal with this by (1) folding swiftly, and (2) periodically wiping the paper with a damp cloth to re-moisten it, paying particular attention to the corners, which dry faster.
As you begin to fold, you will find that damp paper is a recalcitrant medium reluctant to hold its shape. You should avoid making unnecessary creases, as they will show on the finished model and weaken the paper, making it susceptible to tearing. At this point, drafting tape (which looks like masking tape but peels off more easily) can be invaluable. You can use it to reinforce weak areas of paper and to hold layers together until they dry. You can also use it to reinforce areas that several creases run through, like the the center of the paper, but you should put the tape there before you make all the creases. Otherwise, the tape may stick to the fuzz on the crease.
The beauty of wet-folded models lies in their three-dimensionality, so you should not press everything flat. In fact, major features of the body (like the back) look good if you just round the folds, rather than creasing them. Again, you can use strips of drafting tape to hold the shape until the model dries. If the model is to stand on its own, you should tape the feet to a flat surface to ensure that the legs are all the right length.
As you are folding, don’t be afraid to crimp, stretch, or bodge. The thicker paper and softer creases are much less likely to form a jumbled mass of wrinkles where thinner papers might. On the other hand, complicated models with many layers should be avoided because if you try to squeeze too many layers too much, the model will burst.
When you are finished, set the model aside to dry, When it is thoroughly dry you can easily strip off the drafting tape. Minor changes can still be made by bending (but not creasing). Finally the model, beautiful and sturdy, is ready for long-term display.