Hand craft and its bottleneck
Until the early nineteenth century, European paper was made one sheet at a time. A vatman dipped a mold into a vat of pulp, a coucher turned the sheet out onto felt, and the process was repeated. The pulp came mainly from linen and cotton rags. A skilled team could produce a good deal of paper in a day, but output was limited by labor, and supply was limited by how many rags could be collected, sorted and cleaned. As printing and literacy grew, pressure on both fronts increased.
The continuous machine
In 1799, a French mill worker named Nicolas-Louis Robert received a patent for a machine that made paper as a continuous sheet on a moving wire screen. His own business plans struggled, but the idea passed to England. There, the Fourdrinier brothers, stationers and investors, financed further development, and the engineer Bryan Donkin built workable machines in the first years of the nineteenth century. The Fourdrinier name stuck to the design, even though the brothers were backers rather than inventors in the strict sense, and they reportedly lost money on the venture. Contributions are credited differently depending on the source.
The principle is still the basis of the modern industry. A dilute slurry of fiber in water is poured onto a moving, fine mesh belt. Water drains through, and the fibers settle into a mat. The mat is then pressed between rollers, dried over heated cylinders and wound into a roll, all in one continuous run. Another design, the cylinder machine, associated with John Dickinson from about 1809, formed the sheet on a rotating drum rather than a flat wire, and was useful for certain boards and papers.
These machines were driven by steam engines in many mills, which tied paper into the wider story of steam power and the factory system. A mill could produce a sheet of paper that was miles long in a day, rather than counting sheets.
The raw material problem
Machines made paper faster than rag supply could keep up with. Papermakers tried straw, esparto grass, hemp waste and other fibers. The long-term answer proved to be wood.
Wood is mostly cellulose fibers bound together by lignin, a natural glue. Two broad methods were developed to turn it into pulp:
- Mechanical pulping. Logs were pressed against a rotating grindstone to tear the fibers apart. In the 1840s, the German Friedrich Gottlob Keller developed a practical grinder for this, and the pulp is called groundwood. It was cheap but retained the lignin, which makes paper yellow and weak with time.
- Chemical pulping. Wood chips are cooked with chemicals that dissolve most of the lignin and leave longer fibers. Variants include the soda process in the 1850s, the sulfite process in the 1860s and the sulfate or kraft process in the late 1870s. The names of several inventors are attached to these methods, and credit is shared among them. The growth of chemical pulping belongs to the wider rise of industrial chemistry.
Together, these methods meant that paper no longer depended on rags. Forests, rather than ragpickers, became the source, and large mills sprang up near rivers and timber.
What changed for readers and printers
By the second half of the nineteenth century, paper prices had fallen sharply. Newspapers could print on large rolls and reach mass audiences, and cheap books, magazines, wrapping paper, school notebooks and later paper bags and cardboard cartons became everyday items. The ability to print on cheap paper with fast presses supported the growth of print shops and, along with other social factors, the spread of literacy. The effect on the cost of administration, schooling and commerce was large, though no one factor alone explains these changes.
The acid problem
Cheap wood pulp paper had a hidden flaw. Groundwood paper contains lignin, and papers made with certain sizing methods, particularly alum with rosin, become acidic over time. This acid slowly breaks down the cellulose, so many books and newspapers printed between the late nineteenth and the mid twentieth centuries have become yellow and brittle. Rag paper from earlier centuries often survives in better shape than a mass-market book from a hundred years ago.
Libraries and archives have responded with deacidification treatments, microfilming and, more recently, digitization. Since the later twentieth century, many publishers have switched to acid-free or alkaline-buffered papers for books intended to last. The history of paper thus runs from scarcity, to abundance, to a new concern for durability.