Printing Defects
Printing defects can significantly impact the readability and aesthetic quality of a book. As professionals who have worked extensively with heat set offset printing, we understand what causes these issues and how to identify them. Below are the most common printing defects you may encounter in manufactured books.
Banding
Visible repeating density stripes appear, often in large flat areas or gradients.
Barcode/QR scan failure
Codes don't scan reliably due to blur, low contrast, dot gain, misregister, or print damage.
Blistering
Small bubbles/ruptures form (often in coated stock from heatset drying), leaving pits or bumps.
Blocking
Pages stick together (often from ink/coating not fully set). Pulling them apart can tear paper or lift ink, leaving damaged patches.
Broken type
Letters fail to print fully, appearing cracked, chipped, or missing strokes.
Chill roll marking
Repetitive marks or gloss bands appear from cooling/chill roll contact, repeating at regular intervals.
Color cast
Colors look "off" (too red/green/blue) compared to expected; neutrals may not look neutral.
Color-to-color misregister
Process colors aren't aligned, creating halos/shadows around text or images and making edges look blurry.
Crawling
Ink "pulls away" into droplets instead of forming a smooth film, leaving tiny gaps/patches—often tied to poor trapping or surface contamination.
Dirty background
Non-image areas look gray/dirty instead of clean paper-white.
Dot loss
Small dots or fine elements fail to print; highlights look speckled or washed.
Doubling
A faint second image appears next to the main image, making type or edges look shadowed.
Excessive dot gain
Images print darker than intended; highlight detail is lost and midtones look heavy.
Fill-in
Fine details close up; small type, lines, or highlights lose definition.
Fold cracking
Cracks appear along folds where ink/coating breaks, showing white lines (often near the spine or fold).
Ghosting
A faint phantom image appears where it shouldn't, often from mechanical or chemical transfer on press.
Gloss variation
Some areas look shinier or duller than others, especially in large solids.
Gray balance shift
Grays or black-and-white images look tinted (warm/cool) instead of neutral.
Gussets
Wrinkles or folded-in creases that form in the moving paper web, creating a small "tucked" fold that prints through as a repeating crease/wrinkle defect.
Hickeys
Random small circles/voids/spots appear where debris interrupts ink transfer.
Image placement error
The printed image sits too close to an edge or margins look uneven because the image is positioned incorrectly on the page.
Impression marking
You can see/feel the image impressed on the reverse side due to press pressure.
Ink density too dark
Print looks too heavy/dark; shadow detail plugs and text may appear bold or muddy.
Ink density too light
Print looks washed out or weak because ink film/density is below target.
Misregister
CMYK colors don't align perfectly, creating colored halos or fringes that make images look blurry or out of focus.
Moiré pattern
Unwanted wavy/rippling patterns appear in screened images or certain textures.
Mottling
Solid areas or tints look uneven and blotchy, especially in midtones and large flat areas.
Picking
The paper surface (or coating) pulls up during printing, leaving rough white "pick" spots where the image should be smooth and solid.
Piling
Loose fibers/coating build up on the press surfaces and start causing missing ink spots/voids, repeated defects, or gradual print degradation during the run.
Poor trapping
One color doesn't print cleanly on top of another; overprinted areas can look patchy, thin, or unstable (sometimes rubbing off more easily).
Rub-off
Ink transfers by dry rubbing, leaving marks on facing pages or hands.
Scuffing
Rub marks appear where the ink film is physically worn off (often on covers or heavy solids).
Scumming
Non-image areas accept ink, creating dirty, greasy, or streaky tints in margins and backgrounds.
Set-off
Ink transfers onto the back of another page, leaving a faint mirrored image or smudge.
Show-through
The printed image is visible from the reverse side due to low paper opacity or heavy ink coverage.
Slur
Text/images look stretched or smeared in the press direction; circles may look oval.
Smearing
Ink smudges or rubs because it wasn't fully set/dry when handled or stacked.
Spray powder marking
Powder used to prevent set-off can leave visible specks/lines, rough texture, or interfere with ink in spots—especially noticeable on dark solids.
Streaking
Long linear marks run through solids or images, often in the direction of press travel.
Surface scratches
Non-ink scratches or pressure marks appear on the printed surface from conveying or handling.
Tinting
A faint, uniform color wash appears over the entire page when ink bleeds into the press water.
Toning
A light gray haze appears in non-image areas, making the page look slightly foggy or tinted.
Web wrinkling
Creases or wrinkles run through the print, distorting text and images.