"With cyanoacrylate, the resultant repair hardly shows after a finish has been applied"
A Brief History Of Glue
The oldest form of glue known to craftsmen is animal glue. Early craftsmen refined the process of extracting gelatine from a variety of animal tissues, such as hooves and hide, by the application of heat, to produce an efficient and strong method for bonding wooden components.
The Egyptians used casein glue, made from milk.
It was a cold cure glue with a good open assembly time and decent water-resistant properties. It never achieved the popularity of hoof and hide glues, probably because milk was relatively scarce before the establishment of a commercial dairy industry, and its value as a nutrient was most important.
When cabinetmaking came of age in the 17th century, the complexity of structures that developed and the treatment of surfaces with veneers, relied upon animal glue. It is versatile stuff. Perhaps its most valuable asset is that the bond can be reversed by heating - a factor that is exploited to the full by antique restorers.
While talking about shelf life one has to take into consideration how long the container may have stood on a shelf at the suppliers. There is usually no way of knowing this, so it is advisable to buy your glue from a major supplier with a high turnover. If the shelf life is not actually stated on the original container, you will know when you have exceeded it if you begin to notice that the glue has become more viscous with a very short open-assembly time.