Joseph Aspdin

• 1. Introduction

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  Joseph Aspdin patented something he called an artificial stone, and he named it after a quarry that most of his customers would never see. That quarry produced Portland stone, a pale limestone cut on the Isle of Portland along the Dorset coast, prized as the finest building stone in England. Aspdin said his hardened mortar looked like "the best Portland stone," so he called his invention Portland cement. Yet the patent he actually filed describes a soft, fast-setting stucco mix, nothing like the grey, high-strength material that carries the name today. A Leeds bricklayer's paperwork would eventually matter far beyond Leeds. This documentary asks what Aspdin really invented, why his own household split apart over the business, and what became of the name he borrowed from a Dorset quarry.

• 2. A Bricklayer's Ambition

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  Thomas Aspdin worked as a bricklayer in the Hunslet district of Leeds, Yorkshire, and Joseph was the eldest of his six children. He was baptised on Christmas Day, 1778, and he grew up to enter his father's trade as a bricklayer and stonemason. On the 21st of May 1811, he married Mary Fotherby at Leeds Parish Church, formally the Parish Church of St Peter at Leeds.

  By 1817, Aspdin had set up a business of his own in central Leeds, separate from his father's trade. Over the next several years he experimented with cement manufacture, though no record describes those early trials in detail. On the 21st of October 1824, he was granted British Patent number 5022 for his method of making cement. That document, numbered 5022, would put him into a new partnership and pull his family to another town before the year was out.

• 3. Building The Business

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  In 1825, Aspdin partnered with William Beverley, a neighbour from Leeds, to set up a production plant in Kirkgate, Wakefield. Beverley stayed behind in Leeds, but Aspdin moved his family to Wakefield, roughly nine miles away, to run the new plant. That same year, he obtained a second patent, this one for a method of making lime.

  The Kirkgate plant did not last. In 1838, the Manchester and Leeds Railway Company compulsorily purchased the land, the site was cleared, and Aspdin moved his equipment to a second location nearby, still in Kirkgate. By this stage, his eldest son James was working as an accountant in Leeds, while his younger son William was running the Wakefield plant day to day. William's growing control over the family business was about to end abruptly.

• 4. A Father Cuts Ties

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  In 1841, Joseph Aspdin went into partnership with his son James and posted a public notice about his other son, William. The notice read, "I think it right to give notice that my late agent, William Aspdin, is not now in my employment, and that he is not authorised to receive any money, nor contract any debts on my behalf or on behalf of the new firm."

  William did not stay out of the trade. In 1843, he set up his own plant at Rotherhithe, near London, and introduced a new, substantially stronger cement made with a modified recipe, later described as the first "modern" Portland cement. In 1844, Joseph retired and transferred his own share of the business to James. William's hotter, harder mix used a formula his father had never patented.

• 5. The Chemistry Nobody Expected

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  Nothing in Joseph Aspdin's original patent matches the strong grey powder now called Portland cement. His formula was aimed at stuccos and architectural pre-cast mouldings, a market that wanted a fast-setting, low-strength cement rather than a hard structural one.

  That weakness had a chemical cause. Aspdin's mixture was fired at a low temperature, below 1250 degrees Celsius, so it contained no alite, the tricalcium silicate compound that gives modern cement its strength. His product belongs to a wider category called "artificial cements," developed to compete with James Parker's Roman cement, and it closely resembled an earlier product developed by James Frost. Producing even this milder cement still demanded burning the limestone not once, but twice.

• 6. Burning Stone Twice

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  Making Aspdin's cement meant burning limestone on its own first, then slaking it, mixing it with clay, and burning the mixture a second time. Manufacturers of both artificial and Portland cements commonly used this "double burning" process whenever only hard limestones were available to them.

  The reason came down to available tools. Grinding technology at the time consisted only of flat millstones, so it was cheaper to pulverize limestone by burning and slaking it than by grinding it directly. That approach worked, but it depended on a steady supply of limestone, and supply was about to become Aspdin's biggest headache.

• 7. Stealing The Roads

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  The limestone Aspdin used came from the Pennines, a hard carboniferous stone also laid down for paving in local towns and on the turnpike roads. Because that stone was already crushed underfoot, Aspdin's patents, both for cement and for lime, relied on "road sweepings" gathered from those same roads as a raw material.

  When sweepings ran short, he said, "I obtain the limestone itself." In practice, that meant Joseph Aspdin was twice prosecuted for digging up whole paving blocks from the local roads. In the days before stone could be brought in by rail, limestone supply was a constant problem for his business. His son would soon find a different source of stone that never seemed to run out.

• 8. William's Uncertain Legacy

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  William Aspdin changed his father's formula by using a mix with a higher proportion of limestone, burning it at a higher temperature with more fuel, and grinding the hard clinkered material that earlier processes had simply discarded. He never filed a patent for this modified process, and he sometimes claimed his father's patent as his own.

  In 1848, William moved his operation south to Northfleet, in Kent, where soft chalk was available in what the record calls inexhaustible supply. That same year, James moved the original Wakefield business to a third site at Ings Road, where it continued operating until 1900. A history of "financial missteps" and questionable business arrangements suggests William may have been both inept and dishonest, yet he is still credited with launching the modern Portland cement industry.

  Joseph Aspdin died at home in Wakefield on the 20th of March 1855, several years after the cement business bearing his name had already split between his two sons.