"Cracking and Coatings"

Folded brochures that feature full ink or digital toner coverage often show rough or white cracking along the outside edge of the folds.  Several factors add up to cause this:  [1] coated (glossy) paper stock is the primary reason, followed by [2] digital toner versus liquid ink, and lastly [3] fiber orientation on the paper stock.

[1] Coated Paper

Ink soaks into uncoated paper, while digital toner adheres to its "rough" surface.  Coatings give paper a glossy or satin look and feel, but offer far less adhesion for both inks and toners.  Only non-water-based inks will work on coated papers, and specially formulated coated papers must be used for toner-based printing.

 

Most digital toners are plastic- or wax-like powders that are laid down electrostatically and then fused to the paper by heat.  Home inkjet printers utilize water- or alcohol-based inks that sinks into uncoated papers before drying; glossy printing can only be accomplished using specially coated and generally one-sided "photo" papers.  Commercial press printing utilizes petroleum- or plant-oil-based inks that adhere like paint to coated papers.

 

When coated paper is folded, both layers (coating and ink/toner) tend to crack, exposing white paper fibers underneath.  The same cracking occurs on toner-covered uncoated paper because the paper fibers are exposed, but this is not noticeable with ink-covered uncoated paper because the ink has soaked into the fibers.

 

Most papers have wood and/or cotton fibers, and they tend to be oriented one direction or another to give them tensile strength.  Non-oriented fibers create weak papers like those used in tissues.  Newspaper is a fairly weak paper, but one can still see the fiber orientation by the way it tears:  tearing it "with the grain" produces neat strips, whereas tearing "across the grain" creates ragged and unpredictable pieces. 

 

Newsprint is manufactured "fiber-long" and spooled onto large rolls.  Prepackaged sheet paper is labeled "grain-long" or "grain-short" depending on which dimension follows the fiber orientation of the parent paper stock before cutting. 

 

Most digital (photocopy) paper is sold "grain-long" in standard sizes (8.5 x 11, 8.5 x 14, 11 x 17, 12 x 18) because they cause less curling and less jamming in digital machinery.  Consequently, this means most brochures are going to be creased "against the grain," which causes more fiber-breakage than when creased "with the grain."

 

Prepackaged sheet paper the cracking would not be as noticeable if the paper were oriented "fiber-short" (i.e., parallel to the 8.5 inch dimension).  But 8.5x11 stock, and the 11x17 I used in order to give your brochure color that "bleeds" off the edge after trimming, come "fiber long" because they cause less curling and less jamming in digital machinery.

Picture a piece of thin plywood, which consists of multiple sheets of veneer laminated together with glue.  If one were to "fold" it over the corner of a countertop, you would see splintery fibers on the outside edge, whereas the inside of the fold would look like a neater crease or hinge.  If you were to break a single sheet of veneer, similar splintering would occur when bent across the grain, but not as badly as with the multiple-layered plywood; veneer bent with the grain would snap cleanly without any splintering. 

 

Think of uncoated paper like a single sheet of wood veneer; picture coated paper like a three-layered sheet of plywood.  When papers are folded across the grain versus with the grain, the paper fibers are broken, and this becomes more noticeable on coated papers, since the coating adds a "brittle" quality to the paper surface.

 

There is really no absolute solution to avoid cracking along the folds of toner-covered brochures, especially on coated stock.  It is of course much less noticeable if only plain white paper crosses the fold (as opposed to full color coverage).  On heavier stock (card or cover weight), scoring by hand or by machine is mandatory to avoid a ragged fold regardless of whether toner crosses the crease, but scoring is neither advisable nor cost effective for text-weight papers. 

 

Another possible solution would be to print an 8.5 x 11 brochure 2-up on 11x17 paper (without bleeds) or on 12 x 18 paper (with bleeds), which would allow the piece to be oriented so that folding would follow the paper grain.  However, with toner on coated paper, this will only minimize cracking, not eliminate it.

 

Even on a commercial ink press, cracking will tend to occur on coated stocks, although it can be minimized when larger "press sheets" are used that can be turned to orient the grain with the folds (and this is a common practice for the above stated reasons).  But the only way to avoid cracking altogether, as well as to protect the inked surface from showing fingerprints or scuffs from handling, is to apply a "finish coat", utlizing one of three coatings:

These finish coats are available in matte, satin or gloss, and vary in price and availability. Some form of finish coat is highly recommended for durability and professionalism, especially on brochures, folders, and other pieces that are going to be folded, handled, or otherwise exposed to friction. 

 

Due to higher set-up expense, customers typically do not choose press printing for quantities fewer than 1,000.  While certain steps can be undertaken (at added costs) to minimize cracking for toner-based printing, digital color (and black-and-white) is an increasingly accepted production method in the business community for small-run marketing materials or publications that are frequently revised.

 

©2008 Jonathan R. Anderson / AAP Creative