Confirm that the label is completely blank
Stop sending copies and look at the output under good light. A very faint line of text or a missing band across the label gives you a print quality problem to investigate. If every label has no visible image at all, start with the stock, its orientation and the printer’s built-in test. If the printer never moves the stock, check the queue, connection and any warning on the printer first.
| What happens | Check first | What the result tells you |
|---|---|---|
| Every label feeds through blank | Media type and loading direction | Whether the printer can make an image on that stock |
| The printer’s own test is clear | Original PDF, printer choice and page selection | Whether the fault is specific to the job or its settings |
| One blank appears only on loading | Model’s normal loading procedure | Whether the printer is locating the next label |
| Good labels alternate with blanks | Page range and media feed | Whether the job sends extra pages or the printer skips stock |
| There is a pale image or white band | File quality, settings and print path | Whether to move to print quality troubleshooting |
Check how your printer makes an image
Direct thermal printing uses a heat-sensitive coating on the label. The coated face needs to meet the printhead. Check the pack for the words direct thermal and the printer’s loading diagram for the feed orientation. The way a roll is wound or a stack is unfolded can change which face enters the machine.
On the MUNBYN RW403B, MUNBYN shows stock loaded with the printable face up and its branded backing face down. On an unused label, a quick fingernail scratch can sometimes leave a dark mark on the coated face. Use the label’s description to confirm the material. A scratch mark cannot tell you whether the stock has the correct width, backing, gap or other dimensions for the printer.
Thermal transfer uses a ribbon to put the image onto compatible stock. If the exact model and print mode call for a ribbon, check the ribbon is installed, routed and facing as its manual shows. Some printer families include both direct thermal and transfer versions. Read the full model on the case and check the selected print method before replacing stock.
Try a small amount of stock that you know works
Use the sample that came with the printer, or a few labels left from a roll or stack that previously printed clearly. Keep the file and settings the same. If the previously working stock prints and the suspect stock stays blank, check the new pack’s label material and loading orientation before changing the driver.
For the RW403B and similar compatible open-format setups, MUNBYN’s nominal 4×6-inch fanfold stock is a direct thermal option for a controlled test. Use existing compatible stock first if you have it. A Brother QL needs a listed DK roll and a LabelWriter Series 5 needs the supported Authentic DYMO LabelWriter stock, so choose the control sample for the exact printer.
Open-format fanfold supply
MUNBYN 4 × 6 inch fanfold shipping labels
A 500-label fanfold pack for compatible direct thermal shipping printers. The folded stack sits behind the printer and feeds without putting a large roll inside the machine.
Keep in mind. Check the actual printer’s width, gap sensing and feed instructions. These open-format labels are a different system from Brother DK holders and DYMO’s Series 5 authenticated rolls.
- 4 × 6 inch format
- 500 fanfold labels
- Direct thermal media
Run the printer’s self-test with the right stock loaded
Use the manufacturer’s self-test or configuration label procedure if the model offers one. With the RW403B, MUNBYN’s blank-print instructions describe a quick double press of Feed for a self-test. The procedure differs from holding Feed for media identification. MUNBYN also asks owners to check the original power adapter and cord for this model.
If the built-in test prints clearly, the printer can produce an image on that stock. Use the same media for a single page from the computer or phone. If the test is blank on known compatible stock loaded in the right direction, check the model’s instructions for media, print mode and power before seeking help.
Inspect the original postage job if the self-test works
Reopen the PDF from the carrier or marketplace. Select the page with the postage and choose the physical printer in the dialogue or app. Match the paper size and check the preview. If the label is outside the selected print area, return to the carrier’s output options and choose the format intended for the stock.
Send one sample page from another known-working file through the same queue or app. If both jobs are blank while the built-in test prints, recheck the selected queue, manufacturer driver and print mode. If only one file fails, compare the page selection, orientation and layout with the file that worked. Use the original download when testing to avoid adding a cropped screenshot or a re-saved copy to the comparison.
Record the test result before seeking a repair
If the built-in test stays blank after you confirm stock, loading and the documented settings, record the model, media code and light or error message. Note whether there was any image on the test or whether the printer did not complete it. Take a picture of the output or loading path if the manufacturer requests it. You can do this with a sample label that contains no customer details.
Follow the exact maintenance instructions if the manufacturer points you to the printhead or paper path. A completely blank test on known compatible stock is enough information to contact support, especially when the printer was recently working with the same media.
Manufacturer blank-print and media guidance
Checked in November 2026.
Common questions
Why does the printer move normally but print nothing?
Check whether the stock is direct thermal or needs a ribbon, and check which side faces the printhead. After loading supported stock, run the manufacturer’s self-test to separate a media or printer problem from the original job.
How can I tell which side of a direct thermal label prints?
Look at the loading diagram for the printer and check the stock packaging. A quick fingernail scratch on an unused part of the label face can leave a dark line on heat-sensitive material. Use that as a clue and confirm the exact stock before buying more.
How do I run a MUNBYN RW403B self-test?
With the correct stock loaded, MUNBYN’s RW403B blank-print guide describes a quick double press of Feed to print the self-test. Use the button procedure documented for your own model if it is different.
What if the self-test works but my postage PDF is blank?
Check that you chose the correct printer and the intended page. Reopen the original carrier file, match the selected paper size to the loaded stock and look for the full postage area in the print preview.
Why does an extra blank appear after each printed label?
Check the number of pages sent and whether the printer advances one label on a normal idle feed. Repeated blank gaps between otherwise printed labels point you towards the job length, media sensing or calibration.