When chocolate became affordable

Chocolate's move down the social scale is usually credited to one machine or one bar. It was a compound effect, and the components are separable.

Raw material got cheaper as cultivation expanded, first in the Americas and then dramatically with West African production from the late nineteenth century onwards. Volume at low cost changed what a manufacturer could plan for.

Mechanisation reduced labour per unit. Pressing, grinding, refining, conching and moulding all moved from craft operations to continuous industrial processes over the period.

Recipe did a great deal of quiet work. Sugar and, later, milk solids are cheaper than cocoa solids, so a bar formulated with more of them and less cacao costs less to make. Much of what made chocolate affordable was a change in what chocolate was, and the legal minimum compositions that exist today are a response to exactly that pressure.

Fiscal and distribution changes did the rest. Duties on cacao fell over the nineteenth century in several markets, and railways, wrapped shelf-stable formats, branded packaging and eventually the confectionery counter put a bar within reach of an ordinary wage.

The result by the early twentieth century was a product that a working household could buy routinely, in a form its seventeenth-century equivalent would not have recognised.