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Nuts and Bolts

Topics:

Prepping Artwork for Embossing | Determining Grain Direction | Metric Paper Sizes | Glues
More on Stringing


Prepping Artwork for Embossing
Q: As a designer I found the information about embossing and foil-stamping in two recent editions of Post-Press Solutions to be extremely informative. And I totally agree with the advice you quoted from Graphic Arts Monthly-"The designer, the embosser and the engraver should get together at the start of the job." But I wish you would have given specific instructions on how we designers should mark up our artwork to show the embosser what we have in mind. Talking about it is good, but I want to provide specifics with my camera-ready art. Are there any "embosser's symbols"- comparable to proofreader's-to indicate, for example, a gradually-rising embossed surface?

A: Yes, Here are the engraver's symbols that Universal Engraving, Inc., Overland Park, KS, recommends designers use:

-Brian Gebhart
Stamping, Embossing & Die-Cutting Supervisor

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Determining Grain Direction
Q: From time to time you have touched on some of the implications of folding and/or scoring paper either with the grain or against the grain. But how do I tell the grain direction of a sheet?

A: Here are four commonly-used texts (in the following illustrations, the arrow shows grain direction):

  • Moisture test: Moisten one side of a sheet with a damp cloth. The paper will curl parallel to the grain.
  • Tear text: Tear a sheet both longitudinally and latitudinally. Tearing with the grain will be relatively easy and the tear will be relatively straight. Against the grain, you'll feel more resistance and the tear will be more ragged.
  • Folding test: Fold a sheet both longitudinally and latitudinally. Folding with the grain will be relatively easy and the crease will be sharp. Against the grain, the paper won't fold as easily and the crease will be less sharp.
  • Fingernail test: Grip one edge of the sheet between your thumbnail and middle-fingernail and pull a few inches. Then do the same thing with an adjacent edge. The edge that's parallel to the grain won't be affected, but the cross-grain edge will be wavy.

    If all else fails, ask your paper supplier.

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  • Metric Paper Sizes
    Q: I don't know whether it's NAFTA, or GATT, or some other alphabet soup I'm drowning in, but more and more bids are requiring me to deliver sheets in metric sizes, and I don't know a centimeter from a centipede. Can you provide a guide to those "A" sizes in inches?

    A: Maybe it's ISO you're drowning in (turn back a page to my column). In any case, here's your guide:

    A1 23-3/8" x 33-1/8"
    A2 16-1/2" x 23-3/8"
    A3 11-3/4" x 16-1/2"
    A4 8-1/4" x 11-2/3"
    A5 5-7/8" x 8-1/4"
    -Marty Anson

    Glues
    Q: I thought glue was glue, but now some prospects are specifying "cold emulsions" and on occasional bids I'm seeing a requirement for "PUR adhesives." Since I use Bindagraphics to cover the bindery requirements on my bids, I need to know what kind of glue you use.

    A: There are three "families" of adhesives in use in binderies these days. At Bindagraphics we currently see a need to use only two of them.

    "Hot-melt" adhesive has been around the longest and is still the most widely used-it's the norm in perfect binding. Hot-melt glue comes in a solid state and must be heated to liquidity before it's applied. The advantages of hot-melt are that it's relatively inexpensive, applies easily, cures quickly, and makes a very strong bond. Disadvantage: when it cools down, hot-melt glue stiffens, so books bound with it are hard to hold open and tend to snap shut. Readers have a tendency to crack the spine to overcome this "mouse trap" effect, which of course weakens the binding.

    Cold emulsions-or PVA's (polyvinyl acetate adhesives)-are liquid from the get-go and are applied unheated, then gradually "cure" to a flexible, semi-soft state, so they address some of the problems of hot melts. Also, PVAs don't suffer from extremes of heat and cold, as hot melt glues do. On the other hand, PVAs are somewhat more expensive and complicated in application than hot melts. At Bindagraphics, we use PVAs in combination with hot melts in the Otabind® process to bind books that will lay flat and stay open.

    The new kid on the bindery block is PUR (polyurethane) adhesive. A hot-melt process is used with PURs, but as they cure they react with the moisture in the paper and the surrounding air to form a chemical bond with the paper. Once this curing process is completed, the PUR-bond is quite flexible even in extremely cold conditions but won't melt even at temperatures that would re-liquefy conventional hot melts. And PUR works well with all kinds of stock, even coated stocks where other hot-melts and PVAs don't perform well. So PUR-binding is very versatile, very strong and very flexible; is this the new "miracle glue"?

    Maybe. But we aren't using it-yet-at Bindagraphics, for several reasons:

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  • -Howard Corner
    Folding Supervisor

  • PURs are much more expensive that other bindery adhesives, and the systems used to apply them are also more expensive-so PUR-bound books are much more expensive than most of the market will bear.
  • PURs are toxic and difficult to work with. When heated, they release vapors which demand certain costly in-plant precautions-one of the reasons the systems are so expensive. What's more since PURs react with moisture in the air, an unsealed container will start to cure, so costly control systems are required to minimize waste.
  • PURs cure much more slowly than conventional hot melts or PVAs, so total turn-around time is much longer-another addition to cost. And attempting to alter the environment (temperature and mositure) to speed up curing makes the resultant PUR binding much stiffer, thus undercutting one of its main advantages.

    We at Bindagraphics are carefully watching developments in PUR technology, but at present we believe its disadvantages limit its suitability to a narrow market niche where cost is no object.


    More on Stringing
    Q: In a recent Nuts 'n' Bolts column, the writer asked the difference between "stringed" or "looped". As you can see from the enclosed diagrams, the explanation is not correct.

    Looping is accomplished by pushing the middle of a piece of string through a tag hole, forming a loop on the opposite side. Both loose ends of the string are then fed through this loop. This leaves two loose strands extending from the tag (the string is not tied as your explanation described). Strings attached by inserting one end through a hole in the tag and then tying both ends of the string together are considered "knotted" strings or simply "PT & K" (that is, Pulled Through and Knotted). Both looping and knotting are considered "stringing". And both of these stringing methods are accomplished automatically by our automatic stringing machines. In addition, automatic machines attach various lengths of wires to tags.

    Please feel free to contact me regarding tag and label terminology and specifications. I enjoy your newsletter and appreciate being included on your mailing list.

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  • -George E. Phelps
    VP Sales & Marketing
    Allen-Baily Tag & Label Inc.
    Caledonia, NY

  • -Bob Anderson
    Perfect Binding Supervisor

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  • Bindagraphics, Inc.  2701 Wilmarco Ave, Baltimore, MD 21223-3352 USA
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    Site last revised:4/4/2011
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