My paper investigates “durability” as a central but little-explored concept in the history of technical expertise and capitalist development in nineteenth and early twentieth century Egypt. It examines durability as a normative techno-fiscal paradigm through which civil engineers and financiers spoke a common language of accounting and surplus maximisation. Through this analysis of durability, my paper aims to answer two questions. First, is it possible to think of capitalist development without essentialising the productivity thesis? Second, are there forms of economic extraction not oriented toward the goal of increasing productivity? Standard accounts of capitalist development generally concur that surplus accrues from a systematic organisation of productive forces and recruitment of advanced technologies. Other accounts focus on the institutions of capitalism, primarily joint-stock companies as the archetype of this organisation. I interrogate these accounts at the level of technique, allowing for an alternative history of capitalist development to emerge. Financiers normatively demanded that engineers use their technical knowledge to produce durable infrastructures which guaranteed an uninterrupted flow of capital and minimum maintenance costs. Yet, my paper shows that engineers and colonial officials manipulated this paradigm in Egypt, where foreign joint-stock companies were denied ownership of the railroad. British colonial officials collaborated with civil engineers to maximise surplus not by employing durable tracks, but by deliberately using inferior materials which called for British firms to step in to deploy their expertise to repair and reconstruct them. I then link this paradigmatic manipulation to the pivotal moment of 1876, when Egypt plunged into a debt crisis leading to its financial takeover by the European Debt Commission and eventual occupation by Britain in 1882. I argue that the formation of the Debt Commission as a preliminary political institution for the foreign management of the Egyptian treasury was precipitated by paradigmatic manipulations of standard technical and economic practices adopted in Britain. In short, I investigate how various relationships to future surplus were construed in places where foreign political power was involved but joint-stock companies did not operate. I also examine how colonial political institutions emerged from the deliberate manipulation of technical practices and non-standard implementation of technical expertise.