ADF leaves vertical streaks — clean CIS glass & dust lines

Joe B.

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Specialities: Windows 11/10, macOS (Sonoma/Ventura/Monterey), Printers, Networking, Office Equipment

Vertical streaks on scans/copies from ADF — HP, Brother, Canon, Epson

Technician

Hi! Do your ADF scans show vertical lines, faint dust lines, or a repeating black/white stripe down the page? Tell me the brand (HP, Brother, Canon, Epson) and whether the issue appears from the ADF (document feeder) only or also from the flatbed. This helps us decide if we must clean the CIS glass strip, the narrow scanner glass, or the ADF rollers.

Customer

HP OfficeJet. Lines only appear when scanning through the ADF. If I put the page on the flatbed, it’s clean. The streak is a thin grey vertical line.

Technician

Classic ADF symptom. The CIS (Contact Image Sensor) slit glass — the tiny strip next to the main glass — has dust, correction‑fluid, toner, or adhesive on it. As paper moves past, that speck is read as a continuous vertical line. We’ll clean the narrow glass strip, the white reference strip, and the feed path. If you also see multiple sheets pulling, we’ll clean or replace the ADF rollers/separation pad.

Customer

I only see one narrow window. What should I use to clean it? I’ve got microfiber cloths and some alcohol.

Technician

Perfect. Here’s a safe, ADF vertical streaks fix:
1) Power off. Lift the lid to expose the narrow CIS glass strip and the white calibration strip opposite it.
2) Wipe the slit glass with a lint‑free cloth lightly dampened with isopropyl alcohol (≥90%). Clean from end to end; a speck anywhere causes a full‑length line.
3) Clean the white reference strip (no scratches). If stained, use a tiny dab of alcohol and dry fully.
4) Open the ADF cover. Clean feed rollers and the separation pad with water (not alcohol if rubber is soft); remove paper dust, adhesive, and clips.
5) Run a test scan from the ADF at 300 DPI. If the dust line on scan remains in the same spot, re‑clean that section slowly under bright light.

Customer

That helped, but I still get a very faint line on light backgrounds. Could this be software?

Technician

If the vertical line appears from the ADF but not the flatbed, it’s almost always physical contamination. Still, try this to rule out settings:
• Switch between Color/Grayscale and change DPI (200 → 300/600).
• Disable aggressive sharpen/contrast in the scan app; over‑processing can exaggerate faint streaks.
• On Windows, test with Windows Fax and Scan or HP Smart / Brother iPrint&Scan. On macOS, try Image Capture.
If the line’s position never moves, go back and polish the CIS slit glass under a flashlight — look for a pin‑head dot of glue, Wite‑Out, or toner.

Customer

I can see a tiny nick on the strip. Is replacement required or can I mask it?

Technician

A scratch on the narrow glass can also cause a constant streak. Temporary workaround: place a thin translucent tape (e.g., Scotch Magic) smoothly over the scratch to diffuse light — many users get acceptable results. For a permanent fix, replace the ADF slit glass / scanner glass sub‑assembly (often inexpensive for HP/Brother) or use the flatbed for critical scans until parts arrive.

Customer

We scan a lot. Any tips to prevent streaks and those dust lines from coming back?

Technician

Preventive routine for ADF streaks:
• Keep a cleaning sheet or scanner cleaning cloth handy; wipe the CIS glass strip weekly.
• Avoid feeding pages with labels, tape, glue, or fresh marker/White‑Out — residue transfers to the slit glass.
• Every 5–10k pages, clean ADF rollers and check the separation pad. Replace when glossy or hard; this also prevents double‑feed and new lines on scanned documents from paper dust.

Customer

Do different brands place the slit glass in different spots? We have HP and Brother MFPs, plus a Canon.

Technician

Yes — quick reference:
• HP OfficeJet/LaserJet: slit glass is the narrow strip at the left edge of the flatbed; some models hide a second tiny window under the ADF hinge.
• Brother laser MFPs: narrow glass sits to the left of the main glass; the white reference is on the underside of the lid.
• Canon imageCLASS/PIXMA: similar placement; some units have a removable plastic rail to expose the CIS.
• Epson WorkForce: the strip is close to the front rail; open the ADF to access rollers and the separation pad.

Customer

After cleaning, the first scan is perfect, but later the line returns faintly. Could rollers be shedding?

Technician

Exactly. Aging retard/separation rollers and the ADF pad can shed rubber dust that re‑contaminates the CIS strip. If rollers look shiny or leave residue on a cloth, install the ADF roller kit for your model. It improves feed reliability and dramatically reduces returning dust lines on ADF scans.

Customer

Great. After the second cleaning and wiping the rollers, the vertical streak is gone. Thanks!

Technician

Summary: Vertical streaks from the ADF almost always mean a dirty or scratched CIS slit glass. Clean the narrow glass strip and the white reference strip, then wipe ADF rollers and the separation pad. Replace worn rollers to prevent re‑contamination. Need hands‑on help for HP/Brother/Canon/Epson? Open the chat.

Quick answer: the accepted fix

Accepted fix when ADF leaves vertical streaks: Clean the CIS slit glass (narrow scanner glass) and the white reference strip with a lint‑free cloth and isopropyl alcohol; remove residue from ADF rollers and the separation pad. If a scratch exists, use temporary tape masking or replace the slit‑glass assembly.

FAQ

Step‑by‑step cleaning

1. Power off and open the lid. Locate the narrow CIS glass strip beside the main glass and the white reference strip on the underside of the lid.
2. Wipe both with a lint‑free cloth and a small amount of isopropyl alcohol. Dry completely.
3. Open the ADF cover. Clean the feed rollers and separation pad. Remove any adhesive or paper dust.
4. Run a 300 DPI test from the ADF. If a line remains in the same place, re‑inspect for a speck or scratch and repeat.

When software matters

1. Test with a different scan app (HP Smart, Brother iPrint&Scan, Image Capture on macOS, Windows Fax and Scan).
2. Adjust DPI, disable extra sharpening/contrast to avoid exaggerating faint artifacts.
3. If lines appear on the flatbed too, the main glass may need cleaning under the rails.

Sources

• HP — Clean the scanner glass and ADF
• Brother — Cleaning the scanner and ADF
• Canon — Lines or streaks in scanned images
• Epson — Cleaning the ADF and rollers

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