Troubleshooting Direct Thermal and Thermal Transfer Labels

 Print is too light and/or patchy

·      Darkness settings may need to be increased. Watch out though - if you set the printer to the highest settings you may actually cause the print to spread, and in the case of barcodes, make the bars too wide.

·      The print speed may need to be reduced.

·      The printhead could be dirty or damaged. Try cleaning and if this doesn’t work, consider replacing.

·      The drive roller could be dirty and need to be cleaned or replaced.

·      The coating on the label material may be defective and need to be replaced.

·      If the print is too light barcode scanning could also be a problem. You need good, sharp bar contrast for a scanner to work properly. Keep in mind, print that is too dark may create unreliable scanning as well.

 Labels are not feeding properly through the printer

·      Check to see if the sensor is dirty or obstructed and clean it if necessary.  

·      The label length may be less the minimum required for your printer. Rather than changing the “height” of your label, labels can be engineered to print in set of 2 or more labels as they run through the printer.

·      Check to see if the printer is set to “continuous” mode. This is for material that is not die-cut so you will need to change the setting to “label” mode.

·      The label sensor may not be set to align with the label gap properly and you will need to adjust it. For instance if you are printing more than one label across the web, and the sensor falls in between the labels it will think it is in continuous mode. You will need to move the sensor so it hits one of the labels. 

·      Unfortunately, some desktop and mini-printers have “fixed” sensors that you can’t move so this means the label may need to be re-engineered. Converters will typically offset the labels on the carrier so that they hit the sensor’s location in the printer.

·      If you are printing on clear materials, you may need to have a black sensing mark printed on the liner or have a sensing slot cut in the liner.

 Printer stops or delays printing

·      Make sure the labels or tags are properly loaded and that they pass under the sensor.

·      The liner of the label may be too opaque for the sensor to work properly. There are often ways to recalibrate your sensor or ask your label supplier for a different liner.

·      Make sure you are using the right printing substrate mode – “continuous” for non-die cut material or “label” for die-cuts.

·      Check the label and/or ribbon sensors to make sure they are unobstructed.

·      If you are printing with thermal transfer ribbons, sometimes the density of the ink may be too light to be seen by the sensor.  Check your printer manual for instructions on recalibrating that sensor.

 Premature Printhead Failure

·      The “rule of thumb” for thermal printing is to set the temperature as low as possible and only to the point where you get acceptable print quality. This helps avoid thermal stress.

·      REGULAR printhead maintenance is also highly necessary. *

·      Try using thinner materials or reducing the printhead pressure

·      Improper media tension can be problematic. Try to keep it down.

·      Look for uneven surface conditions on your media. Raised areas can abrade the printhead more quickly than the rest of the media surface.

·      If printing with thermal transfer ribbons, make sure they are as wide as or slightly wider than the label or tag. Otherwise, the edges of the media can abrade the printhead.

 * Printhead Maintenance

To ensure consistent print quality, and to maximize the printhead life, it is recommended that you clean your printhead after each roll of ribbons or labels. Q-tips dipped in isopropyl alcohol or special “cleaning cards” should be used. It also helps to wiped down the media feed path with a damp cotton cloth to eliminate dust.

 For best adhesion, we suggest following these steps when applying labels:

• Clean surface to which label is to be applied with denatured ethyl alcohol
• Wipe after cleaning with a clean dry cloth to remove any hazy film
• Keep contamination of adhesive by fingers to a minimum
• When applying label, press firmly over entire surface of label to insure adhesive bond
• Allow your labels to set up 24-48 hours before testing the bonding characteristics

Troubleshooting Thermal Transfer Labels

 The key to successful printing is properly matching your printing media (labels & tags), the printing ribbon and printer settings. Poor Print Quality can be the result of many factors:

 Print is too light and/or patchy

·      Darkness settings may need to be increased. Watch out though - if you set the printer to the highest darkness level you may actually cause the print to spread, and in the case of barcodes, make the bars too wide.

·      The print speed may need to be reduced.

·      The printhead could be dirty or damaged. Try cleaning and if this doesn’t work, consider replacing.

·      The drive roller could be dirty and need to be cleaned or replaced.

·      The label coating may be defective and you need to replace the material.

·      If the print is too light barcode scanning could also be a problem. You need good, sharp bar contrast for a scanner to work properly. Keep in mind, print that is too dark may create unreliable scanning as well.

 Print looks smeared - aka is “bleeding” or “feathering”

·      Attempt reducing the heat / energy settings as they may be too high

·      Try reducing your print speed

·      The image orientation may need to be changed. For instance, barcodes tend to print better in “picket fence” format across the label rather than in “ladder style” that runs up and down the label. 

·      A feathering effect or bleeding effect can also make barcode scanning difficult. Besides doing all of the above, you may need to either enlarge the barcode and/or change the label material.

·      Test another printing ribbon that may work better in your printer and bond better to the material

Print is easily scratching off

·      Make sure you are using the right ribbon for the material being printed

·      See if adjusting the temperature will help. Unfortunately, desktop printers only have a few heat settings and this may limit the amount of adjustment you can make. This leads you back to trying another ribbon.

Print is not crisp and clean – aka it has poor edge definition

·      Slow the printer down.

·      If barcode bars in a barcode are not the right width, try adjusting the heat/energy settings AND print speed.

·      Bars too wide –  overburn is occurring so you need to reduce the heat

·      Bars too narrow – underburn means you need to increase the heat

·      Try a different material with lower or higher sensitivity.

·      Try a different printing ribbon. The label and ribbon may not be totally compatible.

·      If the print is OK but looks grayish or translucent, you are heating the material up too much. Try lowering the heat settings and/or the print head pressure.

Print leaves unwanted marks, streaks or “Dead Spots”

·      This is a common problem of ribbon wrinkles and tension. 

o      Reduce the printhead temperature and pressure

o      Adjust the print head for proper alignment

o      Make sure the guide-bar / strike bar is properly aligned

o      Adjust the rewind tension on the take-up roll and make sure it is properly aligned

o      Adjust the unwind tension on the supply roll. Sometimes it also helps to take the roll off and reload it to make sure the film is feeding straight.

o      Look to be sure the label roll is not migrating side-to-side and out of the feed path. The labels should be flush against the label guide bars.

o      Make sure the ribbon is at least as wide as the label. It can be just as troublesome if the ribbon is too wide.

o      There is the chance the media vendor applied an uneven coating and the media may need to be replaced.

·      Look for “hard” wrinkles in the roll of ribbon. Occasional manufacturing issues lead to poor winding of ribbon from the manufacturer.

 Print has pits and/or voids with imperfect print quality

·      Dust on the label must be removed. If static is attracting dust, try adding some tinsel across the material before it passes under the printhead.

·      If the label surface is uneven or has coating streaks, replace it.

·      The print head may be dirty and need cleaning.

·      There may be burnt out elements (missing dots) in the print head. Try offsetting the print area across the printhead to get your job done and then order a new printhead

 Print has streaks or dead spots

·      This can be caused by poor coating on the label and the material will need to be replaced.

·      The printhead may be dirty and need cleaning

·      A label that is printed with a tint or flexo print may cause problems afterwards when adding thermal transfer information. You may need to ask that heat-resistant / thermal transfer inks be used on your preprints.

·      Elements or pins in the printhead may not be working and thus creating white lines. This can create real problems with barcodes as it can change the width of bars and may them unreadable. Start by cleaning the printhead but if this doesn’t help, you will probably need to replace it

Printing ribbon snaps and breaks

·      Make sure the ribbon is properly loaded in the printer

·      Tweak the unwind tension of the supply roll.

·      Look to see if the printhead is dirty thus creating a heat build-up

·      Check to see printhead heat and pressure may be too high

·      Inspect to make sure the ribbon feed area is clear

·      Verify that the printer is not set on “thermal” mode that doesn’t use ribbon.

Printing has developed excessive noise

·      The printhead heat may need to be reduced.

·      The stripping plate may need to be lowered.

·      Certain material and ribbon combinations are more prone to static and making noise as they peel off each other. You may want to consider using different materials.

Labels stick to the ribbon

·      The ribbon sensor may be on the wrong setting

·      The printhead pressure may need to be lowered

·      The angle that the label leaves the print may be too steep and needs to be changed.

Printing ribbon seems to be slipping

·      Cleaning the printhead will stop the ribbon from sticking to it

·      If the label is too smooth and slick, try testing different ribbons or consider switching to a matte-finished label material.

·      Reduce the unwind tension of the supply roll

·       Increase the rewind tension of the take-up roll