PIXMA MG6120 Faint print when using duplex

[Mr_Bear]

Hello everyone,

I have just noticed that when I print using duplex printing, then print is slightly fainter or lighter than when I print the same document without duplex.

I tested this several times.  If I print a muti-page document choosing "print on both sides", the print is now coming out slightly but noticeably lighter on both sides of the paper  - as opposed to when I print the same document printing on only one side of each sheet.

I have a Pixma MG6120 connected via USB to a Dell Inspiron running Win10.

I can't say for sure when this started happening, but it is very recent.  All my ink levels (including both Blacks -CLI226BK, PGI225PGBK) are adequate.

To the best of my knowledge, nothing has been changed as far as the printer configuration goes.  I have been and still am using "Standard" print quality and have not selected "grayscale".

If anyone can give me some advice or opinion as to what might be causing this - or what I can do to troubleshoot it, it would be much appreciated.

Thank you.

[Darius · Accepted solution]

Hi Mr_Bear.

When the MG6120 prints duplex, it uses ink differently than for single-sided so as to minimize bleed-through.  Part of this is to use less PGBK ink (from the PGI ink tank) and rely more on mixing the thinner CLI dye-based inks.

If the duplex printing is noticibly lighter, this may be a side-effect of the paper in use, or it may be due to some of the CLI inks, such as the CLI-BK or CLI-GY, not flowing correctly.  You may confirm this by performing a nozzle check.  If any colors are faint, ensure the bright orange packaging was removed properly, and that the vent near the label is unobstructed.

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[Mr_Bear]

Thank you Darius for you explanation - that would definitely account for what I'm seeing.

I have confirmed through the nozzle check that there is no problem there.

As a follow-up test, I manually printed to both sides of the same sheet of paper and did not see any signs of bleed-through, smearing, or smudging.  Therefore I'm wondering if Canon provides any option (through settings or a different driver) to let the printer use the same "ink preferences" for duplex that it uses for single-sided.

After posting my question to this forum, I continued later last night to Google this subject and did find an article from 2006 that exactly details this issue and confirms your explanation (the printer was the MP830).  Back then there was no option to change things, but I'm wondering if such an option has since become available.

Thank you again for replying back to me and helping me to understand what is happening and why.

Your help is very much appreciated.