my canon pixma mg3620 is smudging the back of pages when i print double-sided, how do i clean it?

Diagnosis

The smudging on the reverse side of your pages during duplex printing is caused by an accumulation of excess ink and paper dust on the "bottom plate" (the platen) inside the MG3620's internal duplexing mechanism. When the printer flips the page to print on the second side, the paper is pressed against this plate. If the plate is contaminated, it transfers ink back onto the clean side of the page, creating streaks or "ghosting" marks. This typically happens after printing a high volume of documents with heavy ink saturation or when using lower-quality paper that sheds more lint. Because the MG3620 uses a compact internal reversal unit, the plate cannot be reached by standard print head cleaning cycles. You can confirm this is the issue if the smudges appear in the same physical location on every second page, regardless of the content being printed.

How to Fix It

To resolve this, you must perform a physical Bottom Plate Cleaning. This is not a software-only process; it uses a specifically folded piece of paper to mechanically scrub the plate.

1. On your Windows PC, open the Devices and Printers folder. Right-click your Canon PIXMA MG3620 and select Printing Preferences. Navigate to the Maintenance tab and click Bottom Plate Cleaning.
2. When the prompt appears, prepare a single sheet of plain A4 or Letter-sized paper.
3. Fold the paper in half horizontally (width-wise), then unfold it to create a center crease.
4. Fold one side of the paper in half again, creating a "Z-fold" or a thick edge on one side. This creates the necessary thickness to apply pressure to the internal plate.
5. Load this folded paper into the rear tray. Ensure the folded edge is facing down and is aligned perfectly with the paper guides to avoid a jam.
6. Click OK or Execute on your computer screen. The printer will pull the paper through the duplexing path several times. This action wipes the excess ink from the bottom plate.
7. Remove the cleaning sheet. If the sheet is heavily stained with ink, repeat the process with a fresh piece of folded paper until the cleaning sheet comes out relatively clean.

If That Didn't Work

• Manual Roller Cleaning: If smudging persists, the pickup rollers may be slipping, causing the paper to shift and touch the plate at an angle. Use a lint-free cloth dampened with a tiny amount of distilled water to wipe the rubber rollers in the rear feed tray. Rotate them manually to clean the entire circumference.
• Paper Weight Adjustment: If you are using heavy cardstock or photo paper, the MG3620's automatic duplexer may struggle. Switch to a higher-quality 20lb or 24lb bond paper. Lower-grade paper releases more "paper dust" which mixes with ink to create a sticky residue on the bottom plate.
• Disable Automatic Duplex: If the smudging is unacceptable for a specific project, disable Two-sided Printing in the Print dialog box. Instead, print the "Odd" pages first, then manually flip the stack and print the "Even" pages. This bypasses the internal reversal unit entirely.
• Check for Ink Leaks: Remove the ink cartridges (PG-245 and CL-246) and inspect the print head carriage. If there is a pool of ink sitting on the carriage, it may be dripping onto the platen. Gently blot excess ink with a coffee filter—do not rub.

Heads Up

• Never use rubbing alcohol or harsh chemical solvents on the internal rollers or the bottom plate, as this can degrade the rubber and plastic, leading to permanent paper jams.
• Avoid using "Eco-friendly" recycled papers with high lint content for duplex printing, as these contribute significantly more buildup on the internal plates.
• Perform the Bottom Plate Cleaning every 500-1,000 pages of duplex printing to prevent ink buildup from becoming permanent.
• Always ensure your paper guides are snug; if the paper enters the duplexer skewed, it will leave diagonal streaks that cannot be fixed by cleaning alone.