What Professional Window Cleaners Use on Commercial Glass

For routine cleaning, glass industry guidance sets a simple method: soak the glass with clean water, apply a mild, non-abrasive commercial window cleaning solution, then remove all of it right away with a squeegee.

Upper-floor glass cleaned from the ground can be done with a pure-water pole instead. What fits a given building depends on its height, its glass and the condition the glass is in.

• Mild and non-abrasive. A commercial window cleaning solution, applied after clean water has loosened the dirt and grit.
• Off the glass right away. A squeegee removes all of the solution before it can dry.
• No acids. The guidance rules out acidic cleaners, especially hydrochloric (muriatic) and hydrofluoric acid. Acidic cleaners are not recommended on coated glass either.
• Tested first. A small, inconspicuous area is cleaned and checked before the rest.

Source: Proper Procedures for Cleaning Architectural Glass Products, National Glass Association Glass Technical Paper FB01-00. Glass makers can set different instructions for their own products, so check those as well.

• Squeegee. Removes all of the cleaning solution from the glass.
• Pure-water pole. Purified water is pumped up a telescoping pole to a brush at the glass. The technician scrubs and rinses from the ground, and because the water carries no minerals, the glass dries without spotting. See how high a water-fed pole reaches.
• Hand cleaning for detail. Entrances, doors and lobby glass, where fingerprints and splash build up fastest.
• Restoration when cleaning is not enough. Heavy buildup and hard-water staining will not come off with a brush and rinse. That glass needs hand detailing or glass and metal restoration.

• Razor blades and metal scrapers, for routine cleaning
• Abrasive cleaners and materials
• Acidic cleaners, above all on coated glass
• Dirty tools: grit trapped between a tool and the glass, or metal touching the surface, can scratch it

NGA guidance recommends against scrapers, abrasives and harsh chemicals on any glass product, because they can cause irreparable damage.

• Tinted and reflective glass is not cleaned in direct sunlight, because the surface gets too hot for good results.
• Coated glass. Reflective and low-E coatings on the exposed surface need special care, and product compatibility matters. Identify any exposed coating before cleaning.
• Heat-treated glass needs extra care, because scraping can drag surface particles across it.
• New construction glass. Labels, overspray, mortar splash and sealant smears need methods agreed in advance. See the post-construction final clean.
• Hard-water staining will not come off with a brush and rinse. See hard-water stains on commercial glass.

For work from the roof, OSHA 29 CFR 1910.27 requires the building owner's written confirmation that each anchorage is certified. See what your building's access equipment means for the job.

• Which method they will use on each elevation, and why
• What cleaning solution they use, and whether it suits your glass and any coatings
• How they handle construction residue, staining and damaged glass
• For work from the roof: the anchor certification records and the site safety plan
• Whether the crew are the contractor's own employees

The answers belong in the scope of work, so every bid is priced on the same job.

We set the method on the walkthrough, elevation by elevation: hand cleaning and pure-water poles from the ground, aerial lifts and ladders on mid-rise elevations, rope descent and swing stages from certified anchors above seven stories. Glass that cleaning will not fix goes to restoration. Crews are trained, insured S&K W2 employees.

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