Glass cleaning using the osmosis process: The ultimate guide to flawless pure water work

Cleaning with pure water, often referred to as osmosis cleaning, has become a standard in modern building cleaning. But despite its apparent simplicity, there are sources of error lurking in practice that can ruin the result. This guide is based on expert knowledge and explains step by step what really matters.

1 What is pure water and why does it work?

Pure water is water from which almost all minerals have been removed, so that under the microscope it consists almost exclusively of H2O molecules. It offers two decisive advantages:

• Residue-free drying: as it contains no limescale or minerals, surfaces can be left wet and will dry without staining.
• Physical cleaning power: pure water is "greedy" for reabsorbing minerals. It has a surface-relaxing effect, similar to a surfactant, and aggressively washes away organic and mineral soiling (e.g. bird droppings).

2. the golden rule of water quality (PPM value)

The quality of the water is measured via the conductance value in ppm (parts per million). This describes the number of foreign particles per million water molecules.

• Target range: For a brilliant result, the value should be between 0 and 15 ppm.
• Fault diagnosis: If stains appear in a net-like pattern over the entire surface, the water quality is usually to blame. However, if the stains are uneven or visible as runners, the fault is almost always due to the brush guidance or external factors, not the water.

3. step-by-step: the right working technique

To avoid errors, a structured process should be followed:

1. Checking at the beginning: first clean a test window and wait for the drying image (approx. 5-10 minutes) before working on the entire object.
2. Getting started: Guide the brush to the window in such a way that no water shoots uncontrollably into the slat boxes or sun protection systems. Old dirt loosened there can otherwise drip onto the clean window pane later.
3. Frame cleaning: Clean the frames thoroughly first. The cleaning water can already have an effect on the pane.
4. Mechanical cleaning: Scrub the glass surface. If the glass is very dirty, you will feel a sliding resistance ("scratching") over the Pole, which will subside as soon as the pane is clean.
5. Rinsing: This is the most important step. Start at the top and use the brush (or an overspray system) to form a curtain of water that transports the loosened dirt downwards. The last thing that touches the windshield must always be clean water.

4 Avoid common mistakes in practice

• Dirty brushes: Never lay the brush with the bristles on the floor (especially not in flower beds). Store the brush so that the bristles point upwards or are not in contact with the ground.
• Contact with the facade: Avoid hitting mineral plaster facades (reveals) with the water jet. The water immediately dissolves minerals there and splashes back onto the pane as contaminated water. Ideally, switch between windows in a U-movement around the bottom.
• Limits of use: Pure water is intended for maintenance cleaning. Mechanical aids such as blades, pads or chemicals are required for pre-cleaning in the case of extreme soiling (final building cleaning, bitumen, years of neglect).

5 Special feature: The first cleaning with pure water

If an object is cleaned with pure water for the first time after years of conventional cleaning (with glass cleaner/surfactants), caution is required:

• There are often still surfactant residues in seals and joints, which can be dissolved by the pure water and "bleed out".
• Solution: Allow more time the first time, work more slowly and rinse the window a second time after about 10 minutes to remove runners.

Conclusion

When used correctly, the osmosis process is significantly faster and more efficient than conventional cleaning. The decisive factors for success are compliance with the 0-15 ppm limit, clean brush hygiene and the correct rinsing procedure from top to bottom.

This article serves as a reference for professional glass cleaning with pure water systems and summarizes technical best practices for users.