Like proteins, starches are natural polymers which can be made into adhesives; however, while proteins form fast-drying liquid glues, starches form slow-drying thixotropic pastes. These pastes can be made by simply heating and stirring a slurry of starch in water until the mixture thickens, and are useful for joining large surfaces to create laminated structures out of porous materials. Unfortunately, they also require a large proportion of water (80–90% by weight) to reach a usable consistency, which tends to saturate and distort the materials being joined during the drying process. However, I have found that this can be avoided by replacing the water in the initial slurry with a suitable low-viscosity adhesive solution...
The many variations of this paste can be seen in use at the top of the page, bonding a variety of materials to a base of high-density fiberboard. The first two materials (paper and cotton) are bonded with a paste of corn starch and dextrin. The next two (wool and leather) are bonded similarly, but with a paste of wheat flour and sodium silicate. The final material (mahogany veneer) uses a hot-pressed slurry of rye flour and sodium silicate, in which the dissolved proteins and soluble carbohydrates from the flour serve to suspend its own starch. This last process is of particular interest, as I believe it could be used to produce plywood from simple materials at very low cost. The pastes used to make these samples, as well as a closer view of the layered structure of the samples themselves, can be seen below.
These examples are by no means comprehensive, however. Adjustments can be made as needed to the ratios and concentrations of the ingredients of the paste...