Window Cleaning Alert!

Source: Metroclean Blog  Author: Dahlia Kelada, Director of Marketing, Metroclean

Scratched windows are a concern for general contractors and property managers alike. How does this happen? How can it be prevented? Should window cleaning contractors be responsible?

To answer these questions, we must first understand the life cycle the glass on your building goes through.

There are several types of glass used for commercial buildings, including: plate glass (single pane), insulated (double-pane) and tempered glass (safety glass).

Tempered glass is used for its durability; it’s nearly five times stronger than standard glass and doesn’t break into sharp shards. Tempered glass withstands more wind, heat and impact before breaking. Because tempered glass is fabricated using extreme heating and rapid cooling processes, it is often referred to as a safety glass.

How is Tempered Glass made?

Fabricating or making tempered glass goes through four major steps.

1. Sizing: measuring and trimming the glass to desired size and shape
2. Edging: seaming the edges to create smooth, square edges
3. Washing: completely washing the entire surface to remove loose debris created during the sizing and edging process
4. Tempering: heating the glass in a tempering furnace approximately 1200 degrees Fahrenheit, then quickly drying it with a blast of cold air, reducing the temperature to 400 to 600 degrees

What Causes Scratches?

Cause 1

If loose debris is not completely removed during the washing phase of the manufacturing process; it’s likely to be baked onto the glass during the tempering process, making small bumps or “pimples” on the glass surface. Although it may not be clearly visible to the naked eye, these microscopic particles have become the leading culprit to scratched glass.

These particles detach during the normal window cleaning process and can cause major scratching, usually over the entire glass. Even during the construction cleanup of windows (removing plaster, paint, texture overspray, splashed concrete, mortar, tape and stickers), there is a likelihood that fused fabricating debris can be dislodged and dragged across the glass surface.

If you’re finding scratched glass after a window cleaning service, it’s more than likely due to defected tempered glass. Scratches made by fabricating debris have distinct characteristics, and are typically finer and more numerous than common scratches.

Cause2

Damage can also be caused by subcontractors during the construction of the building. Likely causes are from:

• workers placing ladders or equipment against the windows
• masons smearing mortar on glass
• painters dry-razor blading to remove paint
• sanding perimeters of wood doors
• lathers dragging wire lath across glass
• tile contractors wiping tile grout off glass
• interior texture contractors scraping excess texture on a dry window