Billco proactively addresses the changing needs of the glass industry through on-going education, Industry analysis, and hands-on innovation.

Interpreting Marks Found on Glass After Washing

Tips for operating and maintaining your glass washer

Written by: Billco Manufacturing Service Department

If there are marks on the glass, one must carefully examine the marks for clues as to what actually caused them. Determining the exact location of the mark helps to speed-up the process of eliminating the marks.

Identifying and interpreting the most common marks:

  • Scratches can be caused by glass chips in rollers or brushes, or by sagging spray pipes. Scratches can also be caused by processes prior to the washer, like seaming tables.
  • Smudges can be from finger prints, glue from stickers left on the glass, or dirty marks on rollers…especially on rollers in the drying area.
  • Streaks are generally caused by minerals in the rinse water being dried on the glass in the drying area.
  • Defects in glass generally cannot be removed by the brushes in the washer.
  • Stains are usually caused by condensation forming on the glass during shipping or storage. In most cases, these stains have changed the surface of the glass and cannot be removed by brushes and/or chemicals.
  • Random Marks can be glass defects, debris falling on the glass in the drying section or offload conveyor, or droplets of algae dropping on the glass in the rinse section.
  • Repeating marks are usually caused by dirt or an oily mark on a roller in the drying or off-load section. The distance between the marks typically corresponds to one revolution of a roller. The marks are generally in a parallel line.

When investigating a mark on the glass, it is important to determine what surface the mark is on, and the direction of the mark, as it relates to the conveying direction. This information will help to tell you where in the washer to look for the source of the mark. One final thing to remember…if it is necessary to remove a mark by scraping it with your fingernail, or vigorous rubbing with a rag, then it is unlikely that the glass washer brushes will remove it.

If you have any questions, please contact the Billco Service Department at 724.452.7390 or

Download as PDF