A place for PUR in the bindery
01 Oct 2012
PUR (Polyurethane Reactive) adhesives have been in bookbinding, primarily since 1989. The first test in North America was run on the west coast using a homemade application system. Since then, the use of PUR has increased dramatically. In 1995, it was reported that there were 28 users of PUR, and by the end of 2010 this number has increased to 100+ users in North America.
Advantages of PUR over standard EVA hotmelts
PUR has been chosen over standard hotmelt adhesives for many reasons—with superior adhesion and layflat, being the most important ones.
- Adhesion: PUR is unique in that it will bond to lacquer coatings, UV cured coatings, films such as mylar, as well as clay coated paper.
- Excellent Layflat: Films of PUR, when applied at the recommended thickness, are considerably more flexible than standard EVA hotmelts. PUR is suggested to be applied at 0.25-0.3 mm because it is twice as strong as standard EVA hotmelts.
While the adhesion and layflat qualities are very important in the use of PUR, there are many other qualities that provide benefits for the bookbinder.
- Heat and Cold Resistance: Once the PUR adhesive has cross-linked, books bound by these adhesives will not fail at extreme temperatures over 1000C and below -400C. These properties were especially important to a binder in the US who sent books to both the Sahara Desert region as well as areas in Siberia. Since turning from hotmelt to PUR, this binder’s adhesive related complaints have been eliminated.
- Less Wrinkling of Backbone: Binding cross-grained paper with standard hotmelt adhesives causes considerable wrinkling in the gutter area of the book. The lower operating temperature of PUR does not drive the moisture in the paper away from the backbone, the way normal hotmelt does. PUR is also somewhat malleable as it cures, allowing the paper fibres to return to their original orientation.
- Less “Chip-out”: Since PUR is applied at a low temperature and since it is applied at half the standard thickness of hotmelt, there is much less chance for the material to build up on the trimmer knives and nick the cover material during trimming.
- Square Backbone: The amount of PUR applied is considerably less than standard hotmelt, therefore less material is available to be squeezed out when the cover station and side nipping attach the cover and form the back.
- Solvent Resistance: According to Werner Rebsamen’s article “Insidious Solvents” (WB Times, Aug-Sept 2005), PUR is the only binding material today that is totally resistant to solvents and oils. Samples of the cured PUR adhesive have been immersed in oils and solvents, such as MEK and alcohol, that are used in the printing industry and these chemicals have had no effect on the PUR film. Standard hotmelt films are softened drastically and even dissolved by some of these chemicals.
Then there are some additional benefits:
- Cost savings vs. Smythe Sewing: For many years the standard of the industry to produce rounded, hard cover books was to use Smythe sewing and glue the sewn books with a flexible liquid adhesive prior to rounding. A study in Europe has shown that savings of 30%-40% in cost can be realised by milling off the backbone of the folded signatures and then gluing them off with PUR.
- Roundability and Round Retention: Many hard cover books are rounded and backed to provide both aesthetics as well as strength to the final book. By gluing off the book block with PUR, followed by in-line rounding and backing, a significantly greater round can be obtained. As the PUR cures with the book in the rounded state, the retention of the round will be maximised. There will be no “memory” as is found when rounding books that have been glued off with standard hotmelts.
Due to the nature of PUR, special precautions must be taken in order to prevent premature cross-linking and to facilitate clean up of the PUR.
Both open pot systems and closed extrusion systems have been developed since 1989 to specifically deal with these special needs.
- Open Pot Systems: Initially, an open pot designed specifically for PUR was produced by commercial printing in Medford, Oregon. It was on a Muller Martini Star Plus binder. In order to take advantage of PUR, some of the binders on the west coast adopted this application technique.
- Closed Extrusion Systems: The initial closed extrusion system consisted of a premelter, a holding tank, and recirculation hoses feeding the application head. This technology had limited success in the US. A number of years were spent attempting to improve this system. The latest extrusion systems from Nordson Corporation and Robatech, Switzerland have made the application of PUR adhesives relatively simpler.
One of the major concerns for the use of PUR is the price of the material. While the price of PUR is about 3-4 times that of standard hotmelts, the application amount is generally half or less than the amount of hotmelt normally applied. (Welbound has developed a price comparison calculator for PUR v/s Conventional EVA HMA. Please send a mail to email@example.com, for a free copy). As one plant manager put it “a small increase in cost, more than justifies the use of PUR and I can sleep at night, knowing that the job will not be rejected.”
Many users of PUR have found that switching back and forth from PUR to hotmelt is not justified because of this small difference in cost. In addition, operators become much more familiar with the machine settings and are able to maintain the low application levels when PUR is used exclusively.
Another concern involves the emission of MDI, one of the ingredients used to make PUR. The MDI is present in very small concentrations (parts per billion) and newer generations have cut the levels in half.
Then there is the length of time it takes the PUR to cure so the books can be trimmed and shipped. PUR was first introduced into the United States bookbinding industry by the erstwhile National Adhesives (now a part of Henkel International) in 1989. The first generation of PUR, while it could be trimmed inline, needed almost 24 hours before enough strength developed so the books could be shipped. This delay in shipping was found to be completely unsatisfactory for most of the industry.
The second generation PUR was developed in 1994 that allowed inline trimming and sufficient strength within four hours of binding, if enough moisture was present in the paper and the relative humidity of the binding area was high enough.
The third generation PUR was developed in 1997. This generation’s page pull development was achieved within an hour of production and only required the moisture of the paper to achieve final cure. However, since the green strength was very high at an early time, especially in humid areas, it was found that the PUR was becoming very heavy in the glue pot.
Finally, the fourth generation of PUR was developed. This was a lower viscosity version of the third generation and maintained the high green strength, but extended the pot life. This generation has replaced most of the third and second generation PUR, and is especially successful in the new extrusion systems and continues to be used in many systems today
The future of PUR
PUR began its usefulness in binding highly coated and cross-grained paper and this market will continue to be the highest user. More and more printers and publishers are aware of the benefits of PUR and this in turn is driving the demand.
Another emerging market for PUR usage is that of photo albums. These books typically have very high quality paper stock and the purchasers require durability, flexibility, and strength only obtained by using PUR.
The next large increase for PUR will be in the hard cover binding area. Because of the cost advantage of PUR binding over Smythe sewing, and the ability of the fourth generation of PUR to be rounded in line, many hard cover book manufacturers have been investigating PUR.
Another critical application is that of soft cover textbooks in countries that have hot summers. In order to prevent the books from falling apart, the publishers take the precaution of thread sewing or side stitching the book blocks, prior to pasting on a perfect binder. This bottleneck can be removed with the introduction off PUR.
Chuck Cline is a chemistry graduate who worked with the erstwhile National Adhesives for 30 years. He was part of the field trials of most of the 'path breaking inventions' in the adhesives industry including COOLBIND, ULTRACASE and PUR, in the North America. In 2001, he founded 'Binding Solutions LLC', an independent consulting firm.
The Basics of Saddle Stitching
01 Feb 2013
Saddle-stitching is the easiest way to secure a book, together. The process is simple and the machinery involved is less complicated and compact. The process involves bending a fixed length of wire and forcing it through the pages and clinching the legs to form a stitch. It is a cheaper process compared to other forms of binding. You can do approx. 12,000 stitches with 1 kg of wire. Also the machine consumes less space. Saddle stitching basics Saddle stitching is done to print jobs in which the spine thickness does not exceed 1 cm. The wire used for stitching is available in various thicknesses (gauge). The choice of wire is made according to the type of job (the thickness of spine and sheets). For thicker jobs thicker wire may be used since the wire has to penetrate the sheets. The stitcher head is made to handle wire within certain range of thickness. The stitcher head consists of the following components: Wire Straightener: The wire which is drawn out of the spool is straightened Cutter: This cuts the wire to a fixed length to form a stitch Stitcher Head: It bends the wire to form the crown and legs Clincher: It bends the legs of the bent wire from the bottom to form a stitch Basics for a good quality stitch Stitching head Good wire: Wires are normally galvanized. Some-times poor galvanizing creates problems with wire draw. The metal plating on the wire can come off in the straightener. his creates a jam and offers resistance which in turn affects the wire draw and life of the stitcher head. When wire is manufactured it is wound on a large spool; only to be rewound and supplied in smaller spool to fit in the machine. Wire in the smaller spool, if stored for many days, (gets aged ) starts to remember its shape in the spool. Such a wire would offer a lot of resistance to straightening and wire draw. To check the suitability of the wire, draw and cut about a metre length. The wire should coil back to form the size of a football (i.e. larger then the spool from which it has been drawn). Nearly half the problems associated to stitching would disappear when you replace an old stock of wire with a fresh spool. Consistent wire draw: The stitcher head should be able to draw fixed length of wire consistently. You should check the length of wire by drawing them through the stitcher and taking it out after cut. Take about 15 pieces and check if all are equal in length. If it is unequal the quality of stitch will be affected. You can also check the wire after bending, but before clinching, to see if both the legs have equal length. If the legs are unequal, they would either overlap or have significant gap between them. Both these conditions are not acceptable. Good cut: There should not be any burr at the edge of the wire when the cut is made. Ensure that you change the cutter when it starts to give burr at the cut. Centered wire: All stitcher head parts should be properly set according to wire gauge so that the wire is centered correctly in the stitcher head. Clinching: Finally the clinching should be accurate with the correct amount of pressure. The clincher should be clean and devoid of any paper dust. John Finn is the Managing Director, Deluxe Bostich Stitcher Int, Ireland
“Deckle” and Uneven Book Edges
09 Feb 2013
Greeting cards and rare books often feature Deckle edges Shown here is a colored deckle edge “We own a few books where the side (fore-edge) of the text block is not even. The 1st set amount of the pages are about 1/16” out farther than the 2nd set. The 3rd set is about 1/16” out farther than the 2nd set but equal to the 1st set. The 4th set is the same as the 2nd, and so on. It is as if each small binding section of pages was cut at 2 different widths. Is there a name for this type of edge, or is it an error in binding?” Sometimes we receive questions from not only book printers, but from individuals interested in bookbinding. If it gets “technical,” this former teacher has the privilege and pleasure of answering them. Here is one such question I received earlier this month: “We own a few books where the side (fore-edge) of the text block is not even. The 1st set amount of the pages are about 1/16” out farther than the 2nd set. The 3rd set is about 1/16” out farther than the 2nd set but equal to the 1st set. The 4th set is the same as the 2nd, and so on. It is as if each small binding section of pages was cut at 2 different widths. Is there a name for this type of edge, or is it an error in binding?” Let us try to understand this phenomenon. Deckle Edges As we are all aware, earlier papers were made by hand. In this operation, the paper pulp is flowing between the frame and the deckle of the mould. This hand casting operation created unusual, beautiful edges. When papers were made by machine, the paper manufacturers tried to imitate that feature by means of a jet of water or air. Other deckle edges can be formed on dry sheets by means of tearing, cutting with a special type of knife, sand blasting or sawing. In earlier book manufacturing, there were no machines available for trimming the edges. As a result, the folded signatures (sections) were left untrimmed—a tradition carried on until a few decades ago. As a hand bookbinder, I have bound many French books with untrimmed signatures or deckle edges. Such untrimmed edges became popular in the late 19th century and lasted to almost the 1990s. For publishers, we had to imitate such rough deckle fore-edges on common machine made papers for many best-selling books. On folding machines and web-printing presses, we used special, dull knives to create such an effect, with the results, that virtually every single sheet varied in its dimension on the fore edge. Librarians did not appreciate that trend as such bindings collected dust, were unsightly (to some) and difficult to turn. Having explained you the process where we tried to create the deckle edges as an ornamental feature, now let us look at a case where these are developed unintentionally. Web-Printed Variables Book and catalogue offset printing is done in sections of 16, 24, and 32 page configurations. One of the largest printing companies on this continent printed a thick Gun Catalogue. A few days after trimming a smooth edge, the Q.C. Manager sent samples to the RIT book testing laboratory and stated that they are unable to figure out this “phenomenon.” Their client rightfully objected to that “saw-toothed” fore-edge and threatened to reject the entire 100,000+ order. Older books often feature untrimmed, rough edges What was going-on? The answer is simple. When using heat-set web offset printing, printers use one large mill-roll of paper after the other. Each section is printed individually and then stored in a warehouse. It often takes days, and even weeks to print such a large order. Most often, printers operate their expensive web presses around the clock, which mean each crew may have a different idea of how to dry the ink, especially large, solid areas. The crews may use different heat settings. Such fluctuations in the paper and in the printing processes will have some consequences. After trimming, the paper is picking up moisture and then wants to grow back into its final “resting” position. Different heat settings, storage conditions and moisture content in each individual section then results in uneven growths. This description is an experience from an actual consulting assignment where, as is most often the case, the binder gets blamed! Older books often feature untrimmed, rough edges. One large German law-book printing and hardcover binding company I visited solved this problem with trimming the book blocks twice. First they trimmed open the folds. Then they let the book blocks rest for 72 hours, giving the paper a chance to adjust to its environment. A three-knife trimmer in front of their hardcover binding line then did the final trims. Those were the smoothest book edges I have ever had the pleasure to observe. Communications in regards to Trimming As we now know, a book with genuine deckle edges is one a bibliophile will always treasure. Some time ago, a library binder in the Midwest (no longer in business) received such a valuable book from a rare book library with the instructions “Save the Deckle Edges.” When the rebound book came back to the library, the librarian noticed that contrary to their instructions, all three sides were trimmed smoothly. When the librarian lifted the cover, she noticed an envelope. It contained the “saved” deckle edges!
Will education drive print in India?
05 Dec 2018
India has made substantial gains in education. This is a country where 250 million children attend schools. Yet one of its most stubborn development challenges is the fact that 33 million children of primary school age still are not enrolled in school. Right to education is enshrined in the Constitution. The central government launched an ambitious scheme for education. The Sarva Shiksha Abhiyan is an effort to universalise elementary education by community-ownership of the school system. The SSA hopes to provide useful and relevant elementary education for all children in the 6 to 14 age group by 2010. There is also another goal to bridge social, regional and gender gaps, with the active participation of the community in the management of schools. India may boast the record for producing and selling the cheapest textbooks in the world Education is one of the key demand drivers for the growth of print world over. The sheer size of the education market in India ensures that this would probably be the largest factor. However, there are challenges in turning this into a value proposition. Free education – free books Innumerable interventions have been planned for the growth of enrollment. One of it includes: Free textbooks to all girls and socially backward children at primary & upper primary level within an upper ceiling of Rs. 150/- per child (less than $4). The state will continue to fund free textbooks being currently provided from the state plans. As a result, the state government textbook boards form the largest segment of publishers – in terms of quantity of books, produced. All such boards put together are estimated to produce anywhere between 1.5 to 1.7 billion textbooks per annum. That’s not all. The government is laying tremendous thrust on innovative activities for girls’ education, early childhood care and education, interventions for children belonging to backward and needy section of the society. There is a thrust on computer education especially for upper primary level. There is a big opportunity for the book printing industry in India; since the preliminary requirements of the SSA include huge quantities of publishing: school wise/EGS centre wise incentives of free textbooks and notebooks, teaching materials and information system etc. The state government textbooks are printed by empanelled printers selected through a tendering process. Often such tenders see unhealthy compe-tition leading to unrealistically low rates for printing. Huge compromises are then made in the production process, in terms of machines, consumables and quality control. This, in turn, leads to poor quality in production as well as delays in supplies. At times, one has to educate the state board government authorities that one three-side trimmer is the equivalent of three or four automatic cutting machines in productivity of trimming books. And similarly, four automatic pinning machines is equivalent to one online saddle stitching machine. Make and age of machines, special attachments, capacities – these are often not given much importance. In most cases there are no gradations for vendors. The ignorance among government authorities and the unhealthy competition deter highly successful printers who can produce books with better presentation quality. The rate card of NCERT, the premier national textbooks publishing body is a good example. For binding 1,000 signatures of A4 size book, the rate is about Rs 40 (about $1). That means a book of 10 signatures will fetch 40 paise – this is less than the cost of adhesive used in binding the book. Ironically, their tenders have always seen more and more new printers joining the bandwagon. Private education Private publishing The other side of the spectrum is the enormous growth seen in Investment in Private education. With growing income, the huge Indian middle class queue up to send their children to private schools. Today this is a significant part of their annual spend. There are the private publishers who produce textbooks and guides based on the various national (ICSE, CBSE) and state syllabus. Every such segment has a few national players; many more at the state levels. One can estimate about 700-800 million books per annum from this segment. Even in this segment we’ve witnessed a high level of fragmentation and competition. This ensures that the cover prices are very low. In fact India may boast the record for producing and selling the ‘cheapest’ textbooks in the world. “When a textbook on physics reaches a teacher for evaluation and recomme-ndation, there are 30 plus options on the table. The books maybe in different sizes, varying in presentations and in price; but how can the teacher evaluate so many books and decide which is the best for his / her students? Even if your teaching is based on a new book, it will take months before realising if the product (read content) is good. So, then, content is no more the king. It is price and relationship with teacher and school that sells the book. The low entry barrier in publishing ensures that the pressure on pricing is huge,” says Vivek Govil, President and CEO of Pearson Education India. (At the GLOBALOCAL Conference in New Delhi). Also, this makes the value chain unbalanced. Because the student at the top of the pyramid is willing to pay the right price, which is much higher than what the publisher is staking his claim to. (It is only the books on specialisation or super-specialisation subjects that command a premium). The cost of books, as a part of the school education budget in India is a humble 5%. We are not talking about the subsidised books published by the government. For example, a student studying in a private school in Mumbai, following the state board syllabus, would spend anywhere between Rs 20,000-40,000 per annum (about $450-900) on school fees alone. As against this he or she will spend a maximum of Rs 800-1000 ($22) on textbooks, guides and workbooks - all put together. This is an example where the consumer can afford and is willing - but the supplier is not in a position to ask. As there is no value realised, huge levels of compromises are made on both presentation and content quality. Content is often “cut and paste”. Poor quality of paper (50 gsm cream wove white printing paper from a b-grade paper mill is the norm), compromises on design to reduce cost, mono-colour printing, shabby binding and so on. This has made companies like Pearson to focus on complete solutions - including training sessions for teachers, educational aids, question banks, workshops etc; where the book becomes one part of the package and its value is realised in relation to the solution. The academic publisher will forward integrate and invest in educational institutions, thereby realising the full potential of the content. Issues in distribution India is a large country and the rural India still has places that cannot be reached by motors. The free books seldom reach there. The private publishers stay away due to logistical issues. Unless the infrastructure develops in such areas, this will remain a major deterrent. We may need to think out of the box to provide solutions in the short term. For instance in 2009 during a heavy monsoon spell, thousands of school-going children in Bagalkot, Raichur, Bijapur, Koppal, Gulbarga and Gadag districts were distraught that their textbooks and notebooks were washed away in the monsoon floods. If their parents were worried about rebuilding their damaged houses, the children were disappointed at losing their books, with half the academic year over. Responding swiftly to their plight the textbook society, which was established by the State Government, had issued circulars to the Deputy Directors of Public Instruction (DDPIs) in the flood-hit districts to distribute textbooks stored in the block-level textbook godowns (in each taluk) for sale, free so that the children did not lag behind in the studies. The above incident underscores the disparity between India’s haves and have-nots. Even though publishing – and particularly educational publishing forms a large pie of the print market, most of the ‘better’ printers stay away from this for obvious reasons. Lessons to learn Today, a pricing battle is transpiring in other countries, as well. In December 2010, the US Supreme Court affirmed a lower court decision on “the pricing of products made outside the United States.” This has implications for textbook pricing because it effectively prevents the new introduction of low-priced academic books. That’s because internationally sold goods usually work like this: the manufacturer produces two types of the same product. One is expensive and lavish, intended to be sold in the developed world. The other version is cheap and basic, intended for sales in Third World countries. Textbooks work like this too. The real barrier that many students have to accessing inexpensive textbooks is that publishers will only sell them the expensive, lavish version. Publishers make the cheap version, which is really all the students need, but the economic version is available in the developing world. The case came down to this: if the producer makes something intended for foreign sales, can American companies buy the product abroad and sell it cheaply back in America? A victory would have meant yes, and might have allowed Americans to buy textbooks for less money. That would greatly cut into publishers’ profits. This is a victory for American printer-publishers. Perhaps a cue for Indian book printers to tread a similar path, soon...
Gandhiji and Experiments in Printing
05 Dec 2018
I came across this quote: "Contributors should have some pity for the editor and poor compositors. We should take pride in writing a clear and beautiful hand in our own language ... Especially when writing for a publication, everyone should regard it as his sacred duty to be doubly careful." The author is not a compositor or typesetter. It is Mahatma Gandhi and going by his advise, it seems nothing has changed since 1919. Statesman, author, printer Very few know that Mahatma Gandhi was an astute printer, publisher and journalist. Gandhi edited Indian Opinion, Young India, Navjivan and Harijan. On 7 Sept 1919, Gandhi bought out the Navjivan weekly. However, the British government was threatened by the critical writings of Gandhi. Since no printing press owner was willing to risk its business by publishing reports against the government, Navjivan felt the need to acquire its own printing press. Gandhi counted bad printing an act of himsa (violence). He insisted on clear types, durable paper and neat simple jackets Today, Navjivan's annual sales turnover is Rs 1 crore. These are mostly from highly subsidised in-house publications. Add-itional revenue is generated through the copyright of Gandhi's collected works which adds up to 1,000 books. This includes his autobiography, My Experiments With Truth published in 24 foreign lang-uages, including Braille. A glance through Gandhi's body of work is impressive. Gandhi counted bad printing an act of himsa (violence). He insisted on clear types, durable paper and neat simple jackets. He knew costly books in attractive jackets were out of the reach of readers of a poor country like India. During his lifetime, the Navajivan Press printed many books at a low price. His autobiography in Gujarati was priced 12 annas. There was also a cheap edition of this book printed in Devanagari. Gandhi had simple, practical suggestions. He felt children's books should be printed in bold types, attractive paper, and each item should be illustrated with a sketch. He preferred thin booklets. They do not tire out the children and are easy to handle. Curiously, Gandhi was not obsessed with saving money while printing. Once the Navjivan Press decided to publish a Gujarati translation of Gokhale's writings and speeches. The translation was done by an educationist. When the book was printed, Gandhi was requested to write the foreword. He found the translation poor and stiff and asked it to be destroyed. When he was told that Rs 700 had been spent, he said: "Do you think it desirable to place this rubbish before the public after spending more on binding and cover? I do not want to ruin people's taste by distributing bad literature." Gandhi stopped printing his journals when a Government order restricted him. His press was confiscated, his files were destroyed, his co-workers were jailed. He was never discouraged and remarked: "The press has a role to play. It has to become the people's Bible, Koran and Gita rolled in one. A newspaper predicts that riots are coming and all that sticks and knives have been sold out. It is the duty of the press to teach people to be brave, not to instill fear into them." In today's times, the print industry has a lot to learn from the Father of the Nation.