The Problem: It’s Not Just “Dirt” -It’s Mineral Leaching
If you manage a commercial property with a mixed facade (glass, metal, and precast stone), you have likely noticed a frustrating cycle: you pay for window cleaning, and weeks later, white, hazy streaks reappear on the glass.
This isn’t just dirt. It is Mineral Leaching (Silica Runoff), and standard cleaning cannot fix it.
When rainwater hits unsealed precast concrete or stone, it dissolves minerals (calcium and silica) from within the substrate. This mineral-rich water runs down the building and flows over the glass and metal below. As the water evaporates, it leaves behind hard mineral deposits that etch into the glass surface.
Unlike standard dirt, these deposits bond chemically to the glass. If left untreated, they cause permanent Stage 2 corrosion that requires expensive restoration or complete glass replacement.
Why Standard Pressure Washing Makes It Worse
Ironically, many “standard” cleaning methods accelerate this damage.
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Tap Water Residue: Pressure washing with standard tap water adds more minerals to the surface.
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Dish Detergents: Common soaps leave behind oily residues that attract fresh atmospheric pollutants.
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No Leaching Mitigation: Cleaning the stain removes the symptom, but it does nothing to stop the source (the porous stone above).
To truly solve the problem, you must address the entire building envelope, not just the dirty window.
The Engineering Solution: Stop the Leaching at the Source
At Presto Restoration, we treat the root cause of facade staining using a 3-step chemical process.
1. Restore the Glass & Metal (Surface Preparation)
First, we must remove the existing damage. Standard soaps won’t touch calcified mineral deposits. We use Glass ReSurfacer Final Polish, an architectural-grade compound that chemically strips mineral buildup without scratching the glass. For metal panels, we use EnviRestore MSR, which removes oxidation and rust while preserving the anodized finish.
2. Seal the Stone (Leaching Mitigation)
This is the step most contractors miss. To stop the stains from coming back, you must stop the stone from “bleeding” minerals. We apply LeachStop, a hydrophobic silicone treatment, to the precast stone or concrete above the windows. This creates an invisible barrier that prevents water from entering the stone and dissolving minerals, effectively cutting off the supply of runoff.
3. Protect the Envelope (Hydrophobic Coating)
Finally, we seal the restored glass and metal with Glass Defender and Metal Protector MD. These high-performance silicone coatings fill the microscopic pores of the material, making the surface hydrophobic (water-repellent). Future rainwater beads up and rolls off, carrying dirt with it instead of letting it stick.
Prevention: The Role of Pure Water
Once the facade is restored and sealed, maintenance becomes simple. We recommend using Deionized (Pure) Water for all future cleanings. Because deionized water acts like a “mineral magnet,” it grabs dirt from the surface without leaving any spots or residue behind—eliminating the need for soapy detergents that attract grime.
Conclusion: Don’t Clean It. Remediate It.
If your building suffers from recurring stains, stop paying for temporary cleanings. You need an envelope restoration strategy that addresses the chemistry of the materials.
Is your high-rise showing signs of mineral leaching? Contact Presto Restoration today for a site evaluation and a custom facade protection plan.
