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7 Steps to Verify Your Brush Height is Correct

Tips for operating and maintaining your glass washer

Written by: Billco Manufacturing Service Department

In order for the brushes in your glass washer to be the most effective, they have to be operated at the proper height. For the best results, we recommend that only the tips of the bristles should have contact with the glass. A common mistake is lowering the brushes too much and creating too much surface agitation and force. The agitation swath width may result in 5-10 times the suggested width, and generate a greater load on the drive mechanics, resulting in less effective brush contact. Tests created by process engineers and maintenance teams such as the China Marker, Grease Pen, and Sharpie Test are subjective, and often misinterpreted.

In some applications that require greater surface agitation, we suggest a few options including; reducing conveying speed, installing brushes with a greater bristle diameter, increasing the brush RPM, and/or installing a larger brush diameter. Always follow the manufacturer’s guidelines on speed and operation.

Here are 7 steps to verify your brush height is correct

  • Before Starting: Internal brushes and rolls should be reasonably dry. Spray lines should be empty so as to not drip during the test. You will need a large glass lite, or multiple glass lites, so they can span the width of the washer.
  1. Prepare the Washer – Open the washer top and allow the inside to dry. Ensure appropriate safety mechanisms have been used and make sure it is in a safe state before proceeding. The washer must be powered off, locked out and unable to start. Be sure to wear all recommended glass PPE.
  2. Prepare the Solution – Mix a solution of talcum powder (i.e. baby powder) and isopropyl alcohol in a spray bottle. Mixture should be in a low concentration so the bottle still sprays; minimal volume of talcum; i.e. 20:1. To check the mixture, spray it onto a piece of test glass, and allow it to dry.  The ideal coating is a light and uniform white chalky residue left behind after the water dries.   This residue will easily show brush marks on stationary glass.
  3. Prepare the Glass – Carefully, manually place the glass lite(s) onto the conveyor rolls of the brush zones being tested.  The location is typically above the bottom brushes.  Mist the water/talc solution onto the top surface of the glass and allow it to dry. Note:  The top surface of the glass is the most important, as it is the surface being printed upon.  Allow the water/talc to dry, leaving the white residue left behind.  It is important to have the glass spanning a good length of the brushes being tested to check for interference problems.
  4. Position the Washer Top – After the talc is dried onto the surface, lower the top of the washer into the working height.  If  ¼” or less plate glass is being used for the test, this will be the “down” position, or zero position.
  5. Manually Operate the Brushes – With power on and the washer top in the “down” position, start the brushes in manual mode and run for a few seconds. Only the brushes should be started and only for a few seconds.
  6. Check Your Results – Once the brushes are off, raise the washer top to view the glass. The swath width of the brushes should be observed on the top surface. The talcum powder will be removed where the brushes made contact with the surface of the glass. The swath width should be about 3/8” to 1/2” in width, and should run uniformly across the complete width of the washer.
  7. Interpret Your Results – If you need assistance interpreting the results of the test, please contact the Billco Service Team at 724.452.7390.

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

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