Chemical formulations go so far back in time that we must turn to the archaeologist for examples. As long ago as Mesolithic times when people were hunter-gatherers they attached worked flint arrow heads to shafts by means of a blend of resin extracted from birch bark and made plastic with beeswax to produce a substance that had the best properties for the job.

Resin alone, once set, produces a brittle mass but when blended with just the right amount of beeswax it provides not only a strong adhesive but also has sufficient flexibility to withstand the mechanical forces imposed on a weapon such as an arrow.

Found only in certain limestone deposits flint was scarce and often was brought from far and wide. And so it seems reasonable to assume that a great deal of care went into any experiments of which it formed a part. Quite simply, a lost arrow point demanded a replacement that took a skilled person some time to make and required a fairly large chunk of that valuable material.

One can imagine that the process would follow the lines: theory, experiment, result, interpretation, new theory, new experiment, new result and so on until performance was optimized. Those stone-age experiments were in fact an early application of plasticizing a polymer the beeswax was the plasticizer. The product must have been used as a hot melt adhesive which, on cooling, left the flint arrowhead firmly, but flexibly, bonded to its pine shaft.

The very same principle...