Printed Material Defect
5.Printed Material Defect
| No. | Item | Printing System |
Phenomenon/ Situation |
Explanation | Cause | Counter-measure |
| 501 | Printed Material Defect (Post-press) | All Systems | When switching from oil-based ink to UV ink, various issues occurred such as printing defects, foil stamping defects, film lamination defects, adhesion issues with glue, and adhesion failure of water-based varnish. | Due to the different compositions of UV ink compared to oil-based ink, it is necessary to re-confirm suitability before processing. Additionally, there can be differences depending on the UV ink type. Note: Some ink types contain slipping agents, which can make post-processing difficult. | Incorrect ink selection or Instruction error | A) Confirm suitability and use appropriate materials when applying post processing to UV printed materials. B) For glue issues, foil stamping defects, and printing defects, consider using die-cut shapes. Perforations can also be an effective measure for glue issues. C) Review post-press conditions. D) Reevaluate the type of UV ink. |
| 502 | Printed Material Defect (Post-press) | All Systems | Even same UV-printed job from previously, various post-press issues occurred such as printing defects, foil stamping defects, film lamination defects, gluing issues, and adhesion failure of water-based varnish. | When previous job results in defects suddenly, it is often due to the increased hardness of the UV ink film caused by over-curing or changes by passage of time. Additionally, it is necessary to check if there have been any changes in the processing conditions. |
Over-curing Passage of time Post-press condition |
A) Check the UV lamp settings (cure efficiency improves when lamps are newly replaced). B) Review the processing conditions. C) Shorten the lead time from printing to processing. D) Change the ink type. |
| 503 | Printed Material Defect (Set-off, Blocking) | All Systems | Set-off, blocking occurred. | It's caused by curing failure. Contributing factors include the base paper and humidity. | Curing failure, Storage condition | A) Refer to the section on curing failure and address the causes. B) Change the paper. C) Manage the storage conditions of printed materials. |
| 504 | Printed Material Defect (Curl) | All Systems | Occurred curl | UV printed materials are subject to curing shrinkage, causing all of them to curl inward by default. This is especially common in cases of printing on one-sided coated paper, when printing with heavy ink coverage, or when using coating varnish with heavy coverage. | Characteristic of ink | A) Change to a slow-drying (better adhesion) type to reduce curling. B) Reduce the total amount of ink including varnish. C) Change the type of paper. |
| 505 | Printed Material Defect (Ghost) | All Systems | The phenomenon where the image from the first printed side shows through to the surface of the second printed side is known as (chemical) ghosting. | Though quite rare, chemical ghosting can occur even with solvent-free UV inks under certain conditions. This is caused by the migration of low molecular weight gases released during UV irradiation. It is more likely to happen with non-absorbent substrates like film, and also when curing is insufficient. |
Curing failure, Influence by paper |
A) Refer to the sections on curing failure and address the causes. B) Introduce ventilation to disperse any gases released. C) For the second printed side, pre-print with a medium or similar substances to ensure uniform ink transfer. |
| 506 | Printed Material Defect (Ghost) | Offset | The phenomenon where tints or solid areas on the same side of the print exhibit varying shades corresponding to the underlying image is known as (image) ghosting. | When the ink has poor fluidity by nature or its fluidity worsens due to excessive emulsification, it doesn't spread well on the ink rollers, making (image) ghosting more likely to occur. While this can happen with oil-based inks, it is more prone to occur with UV inks, which have weaker emulsification characteristics. | Characteristic of ink or Excessive emulsification | A) Reduce the amount of dampening solution. B) Change the ink type (with better emulsification resistance and fluidity). C) Adjust the imposition. D) Make ink take-off bars. |
| 507 | Printed Material Defect (Odor) | All Systems | There is a characteristic odor specific to UV inks. | A) The unique odor of each type of UV ink is often caused due to the photo initiator. B) If the curing is insufficient, the odor becomes even stronger. | Curing failure | A) Change the ink type. B) Ensure proper curing (refer to the sections on curing failure and address the causes). C) Introduce ventilation or similar measures. |
| 508 | Printed Material Defect (Lightfastness, Weather resistance) | All Systems | Color fading due to light (mainly indoor displays) is Light Fastness. Color fading due to light (UV) + water" (mainly outdoor displays) is Weather Resistance. |
This depends on the structure of each pigment. Particularly yellow, red, and warm-red inks are prone to fading. Essentially, there's no difference compared to oil-based inks, so it’s important to select colors according to the purpose and usage. It gets worse especially in the highlights of halftone dots or with light-colored specialty inks, so extra caution is needed. | Characteristic of pigments or Incorrect ink selection | A) Check the resistance chart and select inks (ultra-lightfast, SR) that use pigments with strong light fastness and weather resistance. B) When using light-colored specialty inks or less than 5% of complementary colors, use super-lightfastness ink or above. |
| 509 | Printed Material Defect (Rub resistance) | All Systems | Even printed materials with sufficient rub resistance experienced scratching during transportation. | When hard particles like sand grains attach to printed materials and are subjected to vibration, scratching occurs. | Manage printed material | A) Prevent the intrusion of particles like sand dust and spray powders. B) Review the packaging methods of printed materials. C) Depending on the situation, it might be beneficial to increase or decrease the slipping character on the ink surface. |
| 510 | Printed Material Defect (Bleeding) | All Systems | Same as oil-based inks, warm-red, magenta, pink, certain black inks, and fluorescent inks can experience issues like bleeding or color fading. | Bleeding can occur with retort, water-based varnish, against contents, and against soap. These issues are caused by the pigments. | Characteristic of pigments or Incorrect ink selection | Check the resistance chart and switch to inks with good soap resistance and solvent resistance. If the resistance is unknown, consult the ink manufacturer. |
| 511 | Printed Material Defect (cracking) | All Systems | During die-cutting, folding, shrink processing, etc., the ink film may crack or chip. In some cases, it may even crack from the original substrate. | UV inks tend to be harder, and more brittle compared to other inks, making them more prone to cracking. Additionally, even among UV ink types, there are variations in crack resistance. | Characteristic of ink or Incorrect ink selection or Incorrect processing selection | A) Reduce the ink volume. B) Switch to a type with better flexibility type (good adhesion). C) Be cautious of excessive curing. D) Optimize processing conditions (adjust cutting blades, folding blades, etc.). E) Consider the image and grain direction. F) Season the base material and printed items (humidification). |
| 512 | Printed Material Defect (Rub resistance) | Offset | Week rub resistance and scratch resistance. |
Case A) UV HY-BD inks and UV inks for non-absorbent substrates are generally weaker in terms of rub resistance compared to quick-drying paper inks. Case B) In other cases, insufficient curing is often the cause of weak rub resistance. Refer to the sections on curing failure. Also, pay attention to lamp systems such as energy-saving systems. |
Characteristic of ink or Curing failure | A) Due to the characteristics of the ink, it is difficult to address this from the ink side. B) Use OP varnish. C) Increase the amount of UV irradiation. |
| 513 | Printed Material Defect (Lines) | Offset | Small lines are appearing from the line towards the tail-end in the printing direction. | The phenomenon of stringing occurs when ink separates from the blanket. It is more likely to happen when there is a high amount of ink or excessive emulsification. Due to differences in ink character and emulsification properties, this is more prone to occur with UV inks. | Characteristic of ink or Excessive emulsification | A) Change the ink type. B) Select concentrated type inks. C) Reduce the supply of ink and dampening water. |
| 514 | Printed Material Defect (poor slippiness) | Coating unit | Due to the poor slippiness of the coater varnish, issues such as scratch the printed materials. | The causes are A) Incorrect varnish selection (slip varies by varnish type). B) Curing failure of the varnish. C) high amount of varnish. D) Higher humidity during printing affects the surface curing of the varnish, leading to changing the slippiness. | Incorrect varnish selection or Curing failure or Printing circumstances | A) Select suitable varnish. B) Refer to the sections on “Curing failure” and address the causes. C) Maintain a consistent coverage amount. D) Implement humidity control. |
| 515 | Printed Material Defect (Lightfastness, yellowing) | Coat varnish | Printed material which using coat varnish including optical brighteners as one of raw material has yellowed while on display. | Due to the fading of the optical brightener. (Optical brighteners have weak lightfastness and need to be cautious. | Incorrect varnish selection | Switch to a varnish type which does not use optical brighteners. |
| 516 | Printed Material Defect (blocking) | Coater unit | Blocking occurred while storing the varnished printed materials. | Common issue is blocking between the base coating layer and the varnish surface on paper with coating layers on both sides, leading to the coating layer sticking to the varnish surface. (Occasionally, this can also occur with UV inks.) This issue is affected by the paper, varnish type, temperature and humidity, and load pressure, as well as by curing failure. | Incorrect varnish selection or Incorrect paper selection or Curing failure | A) Switch to a type considering slip and anti-blocking characteristics. B) Select a substrate with strong surface strength. C) Manage temperature, humidity, and load pressure, both before and after printing. D) Refer to the sections on curing failure and address the causes. |
| 517 | Printed Material Defect (Non carbon paper discoloration) | Business form printing | Discoloration (Yellowing) occurred in no-carbon paper printing. | Reaction occurs between a specific initiator (sensitizer) and the no-carbon paper agent, resulting in discoloration. | Incorrect ink selection | Use Business Form ink. |
| 518 | Printed Material Defect (desensitizing ink) | Business form printing | Inks in contact with desensitizing ink printed areas discolored and bled. | It occurred by using inks formulated that lack of resistance to desensitizing ink. | Incorrect ink selection | Choose inks that are resistant to desensitizing ink. |
| 519 | Printed Material Defect (Reading failure) | Business form printing | OCR or OMR reading failure. | Non-conforming colors were utilized in the creation of special colors, and density control as well as reading checks were not conducted during the printing process. | Incorrect ink selection or Mismanagement of printing | Color matching and printing management are conducted using a PCS value measurement device. |
| 520 | Printed Material Defect (Thermal paper) | Business form printing, Label printing | During the printing process of thermal paper with UV prints, thermal head contamination occurred, leading to printing defects. | This phenomenon occurs from the use of inks with low heat resistance and inadequate head runnability. A similar issue can also occur due to curing failure, even when proper ink is used. | Incorrect ink selection or Curing failure | A) Select UV ink suitable for thermal paper printing. B) Refer to the section of “Curing failure” and correct the cause. |
| 521 | Printed Material Defect (Thermal paper) | Business form printing, Label printing | During thermal printing, the color quality of areas printed by UV ink or areas in contact with UV ink is substandard. | This issue prone to be caused by curing failure of UV ink, as uncured components tend to interfere with and alter the color layer. | Incorrect ink selection or Curing failure | A) Select UV ink suitable for thermal paper printing. B) Refer to the section of “Curing failure” and correct the cause. |
| 522 | Printed Material Defect (Fluorescent ink ghosting) | Fluorescent P Series | When printing with fluorescent P series ink or ink containing fluorescent P series, a ghosting issue was observed on the reverse side. | This phenomenon is prone to occur due to the following reasons: A) Use of an oil-based fluorescent base. B) Excessive ink amount. C) Curing failure. |
Curing failure or Characteristic of pigments. | A) Refer to each section of “Curing failure” and correct the cause. B) Introduce air to the printhead to prevent the dispersion of generated gases. C) To print trans white or similar material to uniform inking. |