how do i clean the scanner glass on my canon mg3620 all-in-one?

Diagnosis

Smudges, vertical streaks, or persistent white spots on your scanned documents or photocopies are almost always caused by debris on the scanner platen (the glass surface) or the underside of the document cover. Because the Canon PIXMA MG3620 uses a CIS (Contact Image Sensor) that moves along a fixed track, any particle of dust, a fingerprint, or a dried ink droplet on the glass creates a "shadow" or a line that repeats across the entire length of the page. To confirm the issue is physical debris and not a software glitch, perform a "blank scan" or a copy of a plain white piece of paper. If you see a consistent line or dot in the same position on every single page, the contamination is located on the glass at that exact coordinate. If the blurriness is general and not linear, it is likely a film of grease or dust across the entire surface of the platen.

How to Fix It

To thoroughly clean the scanner assembly without damaging the delicate glass coating or the internal sensor, follow these precise steps:

1. Power down the printer and unplug the power cord from the wall outlet to prevent any electrical surges or accidental movement of the scan head during cleaning.
2. Lift the document cover fully. Inspect the glass platen for visible smudges, ink streaks, or hair.
3. Use a dry, lint-free microfiber cloth to gently wipe away loose dust. Do not use paper towels or tissues, as these are abrasive and can leave microscopic scratches on the glass surface over time.
4. Dampen a fresh microfiber cloth with a small amount of distilled water or a 50/50 mixture of isopropyl alcohol and water. Crucial: Never spray liquid directly onto the glass; the liquid can seep into the edges of the platen and damage the internal electronics. Spray the cloth first, then wipe.
5. Wipe the glass in a circular motion, starting from the center and moving outward toward the edges. Apply light pressure to remove stubborn fingerprints or ink stains.
6. Lift the document cover and inspect the underside. Specifically, clean the small piece of white plastic or foam (the underside of the lid) that presses the paper against the glass. If this area is dirty, it will leave "ghost" marks on your scans.
7. Allow the glass to air-dry completely for 2-3 minutes before closing the cover and plugging the unit back in.

If That Didn't Work

• Deep Clean with Glass Cleaner: If ink has dried and bonded to the glass, use a dedicated ammonia-free glass cleaner. Apply a tiny amount to a cotton swab (Q-tip) and rub the specific spot of debris. Avoid using ammonia-based cleaners (like some versions of Windex) as they can strip the anti-reflective coating off the scanner glass.
• Check the Calibration Strip: If you see a persistent vertical line that persists after cleaning the glass, the internal calibration strip (the white bar the sensor reads to set its "white point") may be dirty. While this is internal, you can sometimes clear it by performing a "Power Reset": unplug the unit, hold the power button for 15 seconds, and plug it back in.
• Edge Cleaning: Use a can of compressed air to blow out the crevices between the glass platen and the plastic frame of the printer. Dust often accumulates in these gaps and can be sucked onto the glass during the scanning process.
• Verify Document Quality: If the streaks only appear on certain documents, check the paper for creases or "dog-ears." The MG3620 has a very shallow depth of field; any gap between the paper and the glass will result in a blurry or faded area.

Heads Up

• Avoid using acetone, nail polish remover, or harsh scouring pads, as these will permanently etch the glass and ruin the scanner's ability to focus.
• Always keep the scanner lid closed when not in use to prevent household dust and pet hair from settling on the platen.
• If you are scanning old photographs, wipe the photo first; old photo chemicals can sometimes leave a residue on the glass that requires immediate cleaning.
• Periodically check the underside of the document cover; a single staple or piece of glitter stuck to the lid can cause a recurring scratch or dot on every single copy you make.