In the chaotic symphony of a construction site, the window is often treated as a passive observer. It is simply a hole that has been filled, waiting for the rest of the building to be finished around it. Project managers worry about a wayward hammer shattering a pane or a clumsy forklift scratching a frame. These are the loud, obvious risks.
But for modern commercial developments, particularly those clad in concrete, stucco, or masonry, the biggest threat to the glass isn’t a physical blow. It is a chemical attack.
There is a silent, microscopic war happening on the façade of many new buildings. The aggressor is the building’s own skin—the fresh concrete and mortar—and the victim is the glazing. This phenomenon is known as alkaline etching, and once it happens, no amount of scrubbing will fix it.
The Chemistry of the “Runoff”
To understand the danger, we have to look at the pH scale. Glass is largely silica-based and is generally resistant to acids. However, it is surprisingly vulnerable to alkalis (bases).
Fresh concrete, mortar, and stucco are highly alkaline. When water—whether from rain, hose-downs, or morning dew—runs over these uncured masonry surfaces, it picks up calcium hydroxide and other alkaline salts. This creates a “slurry” with a high pH level (often above 10 or 11).
Gravity does the rest. This slurry runs down the face of the building and flows over the windows installed below.
If this runoff is washed away immediately, the risk is low. But construction sites are not window-cleaning operations. The slurry is often left to sit on the glass for days or weeks. As the water evaporates, the alkaline concentration spikes. These chemicals attack the molecular structure of the glass, effectively dissolving the silica matrix.
The “Cloudy” Disaster
When the final cleaning crew eventually arrives to wash the windows before handover, they often discover that the “dirt” won’t come off. The glass isn’t dirty; it is chemically scarred.
The result is a permanent, hazy cloudiness that looks like hard water stains but is actually a change in the surface texture of the glass itself. It looks etched, because it is.
For a luxury high-rise or a corporate headquarters, this is a disaster. The optical clarity of the glass is ruined. Since the damage is structural to the surface, you cannot polish it out without creating optical distortion (“lensing”). The only solution is replacement.
The Cost of the Cure
Replacing a commercial glass unit is not like fixing a home window. These are often custom-fabricated, thermally broken, double or triple-glazed units with specific Low-E coatings.
- The Cost: A single large commercial pane can cost thousands of dollars.
- The Schedule: The real killer is the lead time. Ordering a replacement unit can take 6 to 12 weeks. If this damage is discovered during the “punch list” phase (the final weeks before handover), the project manager is faced with a nightmare choice: delay the opening of the building or hand it over with damaged goods.
The Solution: A Second Skin
The only way to prevent this “chemical cannibalism” is to isolate the glass from the environment entirely. The industry has moved away from taping up plastic sheets (which flap in the wind and trap moisture) toward liquid-applied or peelable film technologies.
These advanced barriers act as a temporary “second skin” for the glass. They are applied immediately after the window is installed. Crucially, they must be:
- Water-tight: To prevent the alkaline slurry from seeping behind the protection.
- UV Stable: So they don’t bake onto the glass in the sun.
- Impact Resistant: To offer the secondary benefit of protecting against weld splatter and scratches.
By sealing the glass under a Skudo window glass protector, the glazing is effectively put into hibernation. The concrete crews can pour, the renderers can spray, and the painters can splatter, all without a drop of material touching the sensitive silica surface.
When the project is complete, the protection is peeled away, revealing pristine glass that has been untouched by the harsh chemical environment of the job site.
Designing for Defense
Architects and builders must realise that glass is not just a transparent shield; it is a finished product installed in the middle of a messy manufacturing zone. It is vulnerable.
Ignoring the chemical relationship between the façade and the fenestration is a rookie mistake that costs millions of dollars in rework every year. The smartest insurance policy isn’t a line item in a contract; it’s a physical barrier that ensures the building’s skin doesn’t eat its own eyes.