Archives for category: Paper

The Kraft process, the chemical procedure used to separate the cellulose in wood from the lignin which binds the cellulose fibers together and provides to structure of a tree, surprisingly (at least to me) was not invented by a German named Kraft. It was actually invented in 1884 by a German named Carl Ferdinand Dahl. The first pulp mill using the process came on line in Sweden in 1890-1. Wikipedia, Encyclopedia Britannica, and Uncle Tom Cobley and all maintain it is called Kraft (strength in German) because it makes strong paper. I wonder. The US Patent for the process makes no reference to Kraft or strength ( — if you do look at this you’ll find an extravagant illustration of the pitfalls of optical character recognition technology). The Oxford English Dictionary tells us that the term kraft paper is derived from the Swedish kraftpapper (which no doubt does mean strong paper) so I suspect we’ve got the cart pulling the horse here, and Mr Dahl’s process picked up its name because it was first used in Sweden to make the strong brown stuff we now call kraft paper. The Kraft process doesn’t have to result in brown paper though: 80% of the pulp produced chemically in the USA uses the Kraft process.

The Kraft process tweaked the earlier soda process, and is sometimes referred to as the sulphate process, after the sodium sulphate it uses.

It certainly takes a deal of craft to follow this diagram, which can be enlarged by clicking on it.

Wood chips, steamed to expand the water cavities in them are mixed with a combination of black liquor and white liquor, and the mixture is then cooked in a digester. After a few hours the chips fall apart into cellulose and lignin plus other byproducts, including turpentine. The black liquor, which is actually produced during this process, was in the past mostly vented into the river which is always to be found next to a paper mill. Eventually we came to realize that this wasn’t exactly good for the fishes, who tended to turn up dead as a consequence.

The cellulose from the digester goes to the blow tank, so called because the cellulose is really blown in there. After that the cellulose fibers are screened, washed, and bleached. Various chemicals, including surfactants, defoamers, dispersing and fixing agents are added to help the pulp perform in production. The pulp delivers from the end of the machine and its driers as a continuous thick blanket. This is cut into sheets and baled for shipment. Most pulp is produced in specialized pulp mills, though there are still a few paper mills which produce their own pulp. Notable among these is Glatfelter — a much appreciated manufacturer of book papers. A visit to their Spring Grove plant in Pennsylvania starts with a visit to their forest! Here’s their video of the pulping process:

If you don’t see a video here, please click on the title of the post so as to view it in your browser.

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Jeff Peachey’s blog tells about splitting paper. Taking a single sheet of paper and dividing it into two sheets each half as thin, sounds insanely difficult. The benefits, if you want to display on your wall both sides of a single printed leaf, are obvious. (One does perhaps have to repeat one’s disapproval of dealers who dismember old books in order to obtain pictures they can sell to intellectual punters.) I don’t imagine paper splitting is as easy as the description suggests though. The things book restorers have to get up to!

Here’s a video from the Morgan Library’s blog showing how it’s done. It all works well, but I think we can assume lots of attempts which don’t work out, resulting in the destruction of a leaf which takes with it whatever information it contained. In other words this is a high-risk activity.

As usual, if you don’t see a video here, please click on the title of the post in order to view it in your browser.

To the book manufacturing operative paper splitting sounds hair-splittingly close to paper slitting. Paper slitting is the cutting of a single roll of paper into two or more ribbons as it races through the rollers at the back end of the press, or in the mill where it has been made in a continuous roll as wide as the Fourdrinier machine it comes from.

 

Ever since linen and cotton rags became too hard to find in sufficient quantities we have been making paper from wood. Lots of other plants have been tried, but wood wins out over all of them. In 1719 René de Réaumur hypothesized that the way wasps chewed up wood to make paper for their binks might be adapted for our stationery purposes. But it wasn’t till 1800 that Matthias Koops, an English papermaker, made a book of which part was printed on “paper made from wood alone”. Friedrich Gottlob Keller’s 1844 patenting of the first practical wood-grinding machine is what made possible the industrial-scale manufacture of paper from trees.  But what is it about wood than makes it suitable for making paper, whether by wasps or men?

Wood is 50% cellulose, 30% lignin, 16% carbohydrates, and 4% proteins, resins and fats. Paper is made from cellulose and that’s what papermakers need, not the rest. Paper makers used to be able to satisfy demand by getting their cellulose from rags, but waste collection limits your supply to the amount of rags people are throwing away, or what you can collect from textile mills as off-cuts and waste. The specialized making of paper from linen rags still goes on however. Cellulose is composed of tiny thin fibers. The fibers in different bits of a tree differ, as do fibers from different types of tree and from trees grown in different climates. Softwood trees (conifers) produce longer fibers than hardwoods, whose fibers are denser. The cellulose fibers are held together in a tree by lignin, a complex organic polymer which also provides the structural support. To make good lasting paper you need to be get rid of lignin.

The structure of wood is illustrated in this video:

Wood burns, it floats in water, and it’s hard enough to bend a nail. The chemical structure of wood is not reproducible by one formula: it consists of too many different constituent parts. It is, however, made up mostly (about 98%) of carbon (c.50%), oxygen (c.42%), and hydrogen (c.6%): Cellulose’s chemical formula is (C6H10O5) and lignin’s C9H10O2,C10H12O3,C11H14O4. Wood also contains small amounts of  nitrogen, calcium, potassium, sodium, magnesium, iron, and manganese.

I was interested to discover from the second video that the cellulose chains in the middle of a tree are aligned in spirals while on the outer layers they are vertically aligned. This allows a young tree to bend, and an older one to stand up against the wind.

Finally, as a lagniappe*, here’s a sort of wood-structure ballet from an Open Culture tweet. 

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Just as I’m finishing this off, here comes a post suggesting we may one day, Dr Doolittle-like, learn to speak to the trees. Maybe once we learn what the trees have to say about us we’ll have to stop making paper books. Is sympathy for plants more of a risk than the ebook?

For the indefatigable, that link includes a link to a TED Talk by Canadian ecologist Suzanne Simard about communication between trees.

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* I had assumed this was a word coming from southern Europe, but no. Apparently it was a Louisiana French word derived from Creole which had picked it up from Quecha. For non-Americans therefore I should perhaps explain that it means a small gift given by a merchant at the time of a purchase; what in Britain we’d call the baker’s dozen.

 

Is it depressing that a Google search for papyrus will return a page filled with links to the chain of stationery stores, Papyrus? Maybe not; after all what right do we have to assume that the internet isn’t all about business and retailing stuff?

Papyrus is of course the precursor of paper (and indeed the word’s origin).  Cyperus papyrus is an aquatic plant native to Africa. Its pith, cut into strips, would be woven into flat flexible sheets by ancient Egyptians (and others more recent) on which one could write. After the woven sheet had dried out under a weight it would be burnished with a stone to make it smoother. As you can see from this video, the stem has a triangular cross section which almost demands this sort of treatment.

Papyrus “books” were formed of several sheets of papyrus, joined together and rolled up to form a book roll. Writing on papyrus, which although its surface is pretty smooth (the lady in the video tells us its derivation is from the word for baby’s skin), demands different techniques than writing on paper — brush rather than pen. The Wikipedia article is comprehensive. Oddly, papyrus was called wadj, tjufy, or djet in the ancient Egyptian language. I guess this means the Greeks named the paper after the plant.

Papyrus is also a rather over-ornamental typeface designed in 1982 by Chris Costello. It’s the typeface, used, as Ryan Gosling’s character in this Saturday Night Live video is unable to get over, for the title sequence of the film Avatar.

(Link thanks to Lois Billig.)

A Hollander is a machine used to beat bits of fiber (here probably cotton rags) into a pulp, breaking the fibers down into small enough pieces to form a sheet of paper.

gif from Paperslurry

The name implies a Dutch origin, and indeed the machine was developed in the Netherlands in the late seventeenth century to replace the stamping mills which had previously performed this function, much more slowly.

Rotating metal blades within that black housing rotate like a mill wheel in the flow of slurry (just water and fiber) which circulates in the race, getting broken down more and more as time passes.

Here’s an unusually gigantic Hollander in operation at Papeterie Saint-Armand in Montreal.

Bear in mind that the materials used in paper making in the seventeenth and eighteenth centuries were primarily cotton and linen rags, so don’t think of a Hollander as chomping up bits of trees! The earliest recorded use of wood for paper making (apart from the action of wasps, which Réaumur hypothesized in 1719 might be adapted for our purposes) was in 1800 when Matthias Koops, an English papermaker, published a book part of which was printed on “paper made from wood alone”. It wasn’t till 1844 that Friedrich Gottlob Keller patented the first practical wood-grinding machine, thus enabling the development of the groundwood paper industry.

Adriaen van de Velde:
A Farm with a Dead Tree
1658
https://www.nationalgallery.org.uk/paintings/NG867

We don’t hear this slur any more do we? In the early days of ebooks the enthusiasts promoting digital access used to use the term to try to persuade even more people of the wickedness of print publishers, initially newspaper and magazine publishers, but subsequently book publishers too. Defiantly the blog Dead Tree Edition, a blog focussed on the periodical business, celebrated its seventh anniversary a couple of years ago with a discussion of the term “dead tree edition” pointing out that things haven’t worked out as the skeptics expected.

Who knows where we are going, but where we are seems pretty unambiguous: ebook sales have settled around 20-25% of total book sales —yes, yes, you who are always so quick to object, I refer to book sales from traditional publishing. Sales figures for self-published books, which we assume are mainly ebook sales, are unsurprisingly rather hard to come by. We know they are large (or we think we know this) but what implication that’d have for the overall total of books sold is hard to know for sure. After all the value of sales of print books remains immense whatever the picture. Emphasising once again that these sales numbers are not really available by anything other than extrapolation, one suspects that they are not as large as the total sales of traditional publishers. I showed suggestions in a post last year that in 2015 self-publishing sales at $1.25 billion were in fact less than 5% of traditional publishing sales, in other words only about 20% of traditional publishing ebook sales. Now I am perfectly willing to be proved wrong on these detailed numbers — I suggest however that whatever the numbers the discussion is irrelevant. Who cares whether the source of people’s reading is Messrs Indie Publisher or Random House? That they read is the important bit. Certainly nowadays many people seem content to continue reading on paper. Maybe they won’t in the future. Maybe they will. It doesn’t matter — publishers (self or trad) will still be there to provide materials whatever the preferred format may be.

The dead tree slur of course refers to the need to chop down trees to make paper. US paper makers are energetic in their commitment to sustainability. You may dislike managed forests, but the industry aims to plant one tree for every tree cut down. Printing overseas may expose you to more ambiguous fiber sources, as I suggested a few years ago.

Paper artist Ray Tomasso from Denver tells you in this YouTube video all about the history of paper making while making several sheets of paper in front of you.

This video is almost an hour long, but well worth watching. (If you don’t see the video above this paragraph, please click on the title of this post in order to view it in your browser.)

When I was reviewing Mark Kurlansky’s Paper, I suggested that there might be an interesting story behind wallpaper — one of the many topics he fails to enlarge upon. There is.

Wallpaper isn’t something you are careful to preserve. When you redo your house, you tend to rip off the old paper, little recking the needs of paper historians 500 years in the future. This means that solid evidence is rather thin on the ground.

Chinese walls had been being papered since at least 200BC, but European wallpaper got started in the Middle Ages, as a cheaper substitute for tapestries or brocade-lined walls. According to the Wallpaper History Society, “The earliest papers are often called ‘black-and-white’ papers because they were printed in carbon ink and often used to line the inside of wooden boxes, or chests. A fragmentary design that includes the arms of England surrounded by Tudor roses, masks and vases of flowers has been found at Besford Court in Worcestershire; c.1550-70 in date.” And wallpaper had become popular enough in the 16th and 17th centuries for the Protectorate under Oliver Cromwell to ban its manufacture, encouraged by the Puritan government which saw wallpapering your wall, like so much else, as irredeemably frivolous. Later governments however saw wallpapers as revenue enhancers — they were taxed in Britain from 1712 to 1836.

Early wallpapers had of course to be manufactured as sheets of fairly small dimension — limited by the size of mould which a vatman could handle. It wasn’t till the invention of the Fourdrinier machine that rolls could be produced and these would be printed by rotary letterpress machines bringing wallpaper to the masses (well, the middle classes anyway). If the advertisement above is realistic it shows a deliberately anachronistic printing scene: the hand press, if used on a roll of paper, had to be being used as a sort of de luxe harking-back to the olden days.

Printing of early wallpapers would be by wood block. Today you can see people in India stamping cloth with inked wood blocks in almost exactly the way in which early wallpapers would be done.

Next Cole & Son show similar block printing, on a slightly more industrialized scale, plus hand screen printing and also the use of a large web press of indeterminate type.

As this next Laura Ashley video shows (expensive) wallpaper is one of the applications for which rotogravure is still used. This is hardly surprising, as color fidelity across long runs is perhaps even more important in wallpapers than it is for green pea can labels.

(If you don’t see videos here, please click on the title of this post so as to view it in your browser.)

Texture can be added to wallpapers, either by flocking, originally done by adding woollen fluff to the ink, or by embossing the paper. Anaglypta (a word featured twice in The Blackhouse by Peter May: surely once is enough for any mystery novel) is not a word I’d ever come across before, though I was, it turns out, brought up with anaglypta wallpaper in our bathroom. The house had been built in 1874, (and divided into flats after World War II) so this bit of decoration couldn’t have been original since Anaglypta wasn’t invented till 1887. Frederick Walton developed Lincrusta wallpaper as a substitute for pressed plasterwork in 1877. A mixture of linseed oil, sawdust, resin, chalk, zinc oxide is spread onto a paper base. Rollers embossed a relief design into the coated paper. Anaglypta was created by Thomas Palmer 10 years later as a cheaper alternative: it omits the coating, and is thus less durable, but clearly survived long enough for me to be able to push in the little raised bubbles in the design. But maybe it was Lincrusta I was destroying after all: the timing would be a little better.

The Victoria and Albert Museum has A Short History of Wallpaper, which focuses rather on the development of the literary trope of wallpaper as metaphorical cover-up. We still talk of papering over our differences.

We are used to wallpaper being printed with a repeating design, but the real top-of-the-market stuff features scenic tableaus. Panoramic landscapes first became popular in France. To cover the walls of a large room without repeating a scene, 20 to 30 lengths were printed, with each length about 10 feet high and 20 inches wide (300cm by 50cm). To print such scenes, using thousands of hand-carved blocks and hundreds of colors called for precision. Printing on multiple sheets which would then be glued together, color and pattern matching had to be spot on. The Zuber company in Rixheim and Dufour in Mâcon and Paris were the main producers. The Zuber wallpaper in the Diplomatic Reception Room in the White House is a famous example. It was salvaged from a house in Maryland, and was only installed in the White House in 1961. See History Magazine for more on this.

The Zuber wallpaper in the Diplomatic Reception Room, circa 2009. White House Historical Association. See WhiteHouseHistory.org

The Zuber company still exists, producing the same sort of meticulously painted scenic wallpapers. They have a fantastic video at their website. Although the website is all in French (there is an English option), there is no commentary on the video. The only sound is a somewhat frantic music track: just turn off your sound, I’d suggest. This is the video to watch: it shows a medieval-looking plant in production. The number of wood blocks for each panel is mind-boggling, and their storage almost unbelievable. The website, which is well worth ranging through, tells us their wood blocks are listed as historic monuments!

I can’t even bear to think what papering a room in Zuber paper would cost. No wonder the White House used a salvaged set.

Louis-Nicholas Robert (also known as Nicholas-Louis) was the first to make a paper-making machine, which he patented in Paris in 1799. It made a continuous roll of paper by using a paddle-wheel to scoop pulp up onto a wire mesh where it was drained and then compacted by rollers in the press section. But Robert was unable to develop the machine, and the scene of action moved from France to England, where two London stationers, Henry and Sealy Fourdrinier invested £31,830/16/4 in a vain attempt to commercialize the concept. After they went bankrupt the idea was taken up by Bryan Donkin who in 1804 built the world’s first practical paper machine at Two Waters Mill in Hertford.

The Fourdrinier’s return on their huge investment was the immortality of having the machine named after them. After development the Fourdrinier machine, which is still the workhorse of the paper industry, operates as shown in this exploded diagram.

(Both illustrations are taken from J. H. Ainsworth’s quaint Paper: The Fifth Wonder*, Thomas Printing & Publishing Co. Ltd, 1959.)

The pulp in the head box is in a solution of 97% water, and flows out through the Slice, an adjustable opening allowing thicker or thinner paper to be made. Fibers released onto the Wire will want to align themselves in the direction of the flow so the whole unit is shaken a bit from side to side so that some of the fibers end up overlapping one another thus increasing the strength of the bonds. The Wire extends from the Breast roll to the Couch roll (pronounced “cooch” in the paper world) with Table rolls and Suction boxes between them promoting drainage. When the paper leaves the Wire it is still 80% water and the Presses compact it and force out more water, getting it down to 60% or 70% water when it jumps over to the Dryers where heated felts evaporate off more water. In the Calendar stacks the paper is ironed by slippage between rollers, then wound up on the Reel and rewound to desired lengths and widths by the Winder.

Here’s a 4 minute video of Kraft paper (brown paper) being made on a huge Fourdrinier.

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For what came before, please see  four earlier posts “Paper making by hand”, the first of which can be found here.

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* For those who want to know, the other four wonders are motor vehicles, meat, steel, and petroleum. Mr Ainsworth has ranked his wonders in U.S. sales volume at 1959’s values.

Foxing — those brownish yellowy spots you often see in old books — appears mainly to occur in machine-made papers from the 19th century. Surprisingly the cause seems to be unknown. The contenders are either impurities in the pulp or size leading to fungal growth, or the presence of iron leading to what in effect would be rusting, or some problems with the bleaching process. Such testing as has been done has unfortunately found no evidence of fungi. It does show acid and iron relatively higher in relation to the rest of the sheet, but nobody seems sure whether the iron is a result of the foxing rather than the cause. The process does seem to be accelerated by humidity. Foxing doesn’t affect the integrity of the paper, and methods of “curing” the problem seem likely to damage the paper (e.g. spot bleaching), so it’s better just to accept the splodges as merely an aesthetic problem.

The fact that we don’t make papers nowadays that fox seems to suggest a manufacturing problem. The paper industry makes constant process and cleanliness improvement, and even if we don’t know what the cause of foxing is it seems to be something we are no longer up to. The Oxford English Dictionary‘s earliest reference to foxed paper is from 1848, but they do have one from the previous year referring to foxing in timber. To me that rather tilts the likelihood of causation towards an “impurities in the pulp” explanation. It seems odd that nobody has done the research though: I guess there’s no financial incentive to find out now that we don’t seem to do it any more.

Among other uses of the verb to fox are the following: to delude (as we’d use it in school, where we’d also use the same word to mean to unearth wrong-doing — it all depended on context); to have your nose turn red by excessive drinking; to turn sour in fermenting (of beer); to repair boots or shoes by renewing the upper leather; to trim a horse’s ears!