by Jason Darrah
What Is Banding?
Banding is a defect in inkjet printing that will appear as horizontal or vertical lines, streaks or bands in the printed output. Everyone will eventually experience some type of banding with their inkjet printer. To resolve the issue, it is important to quickly identify the type of banding that is occurring.
Banding Due To Media Advancement
Distance Banding (Step banding)
- Appearance: Uniform light or dark horizontal lines
- Cause: Media advancing too fast or too slow
- General solution: Recalculate or adjust the media advance
Skew Banding
- Appearance: Uniform light or dark horizontal lines on either side of media
- Cause: Non-uniform media advancement
- General solution: Better media loading
Banding Due To Ink Jetting
Blocked Nozzle (Missing nozzles)
- Appearance: Light, horizontal lines
- Cause: Complete printhead nozzle blockage
- General solution: Purge and/or clean printheads
Deflected Nozzle (Deflection)
- Appearance: Light or dark horizontal streaks.
- Cause: Ink that jets at incorrect angle and lands in an incorrect position on the media typically due to a partial nozzle blockage
- General solution: Purge and/or clean printheads
Chromatic Banding (Directional Banding)
- Appearance: Horizontal bands of alternating color
- Cause: Inverting of the ink order being laid down (CMYK to KYMC) from one pass to the next when printing in bidirectional modes using solvent inks
- General solution: Perform a printhead alignment
Banding Due To Dot Characteristics
Gloss Banding (UV Curing Banding, Bi-directional banding, Lawnmower Effect)
- Appearance: Horizontal bands that are similar to seeing a mowed lawn and seeing the directional passes of the lawnmower
- Cause: Difference in light reflectance characteristics between passes when printing bi-directionally using uv-curable inks. The effect will vary depending upon viewing angle and distance and is more pronounced in darker images.
- General solutions: Print in unidirectional mode or higher print quality
Vertical Banding (Dot Gain Banding)
- Appearance: Darker vertical or horizontal bands
- Cause: Ink drops that do not maintain the correct size or position due to substrate surface energy, heat settings or change in distance between media and printheads
- General solutions: Adjust heat and/or vacuum settings
Comb Banding
- Appearance: Horizontal streaks due to light reflections o the peaks and valleys of ink on the substrate
- Cause: A media with low surface energy that prevents the ink drops from flattening properly
- General solutions: Reduce ink restrictions, print at a higher quality or change media
Banding Due To Limitations In Image Rasterization
Gradient Banding
- Appearance: Bands that are seen in large gradients.
- Cause: e mathematical limitation in the number of halftone levels available in 8-bit images.
- General solutions: Add a small amount of distortion, such as a Gaussian blur and/or render at the RIP with 16-bit processing.
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