There is a great deal of confusion about whether it is necessary to knockout varnishes, inks, coatings, etc from the cover and text of a book. These questions have persisted throughout my 28 years in the business, and understandably so, considering that we are now dealing with digital inks, toners, new varnishes and glues. A recent discussion on the Binding Industries Association listserv dealt with these issues and there was unanimous agreement on how to treat materials that need to be bound.

The bottom line is that you should knockout all inks, fuser oils, varnishes, and coatings from the spine and hinge score area. The hinge score is generally 1/4" from either side of the spine.

Over the past 10 years, the use of PUR glue has become widespread, and this adhesive seemingly offers greater latitude with the use of coatings and toners. PUR glue does adhere to all of the above materials. However, the side glues commonly in use are not made of PUR, they are pressure sensitive hotmelts. The side glue is the weak link. Our side glue sticks to everything except for some digital fuser oils.

The safest course of action is to, as one binder put it, knockout any area that receives glue.

There are lots of gray areas, such as with light ink coverage, or perhaps the job has been done before with no knockout and it has worked. In these cases, I would say that chances are it will work again, but there are no 100% guarantees. If you change your aqueous coating formulation will that take to the glue? That is an unknown. Again, the best thing to do is knockout any area that receives glue.

Check out this article about this world record folding job. Think these participants can now relate to what we go through in the bindery?

To all our friends in the graphic arts world, we wish you a very happy holiday season and a rewarding, fulfilling 2012.