Can window cleaning hurt the window seals?

Ask about a window's seal and two different parts can answer to the word. The published lines about cleaning are written about each of them separately, so it helps to name them before reading what the documents say.

The first is where the glass meets the frame. NGA writes that insulating, laminated and decorative glass is glazed with sealants, gaskets and/or tapes, the materials that hold a pane in its frame. Its warning about them is written about the glazing pocket, where the edge of the glass is held.

The second is inside the glass unit itself. Cardinal Glass Industries defines insulating glass as a unit that “consists of two or more panes of glass separated by a spacer and sealed around the edges to create an insulated airspace.” That edge seal is what keeps the space between the panes closed, and the fog-between-the-panes problem that goes by seal failure belongs to it.

NGA's warnings touch both. Its line on glazing materials is about the first seal letting chemistry through toward the second. Its line on insulating unit sealants is about the second directly. Neither line is about the face of the glass.

NGA's line about the first seal is short. Glazing materials, it writes, “do not provide a sufficient barrier” against cleaning agents getting into the glazing pocket, and once there those agents can damage the edge of the glass or affect the insulating unit's seal.

Read that as a path, not a verdict. Solution applied to the face of a pane runs down to its edge, and the sealants around it are not a wall that ends the trip. The method page walks through what the frame does not stop in full; the point here is that the risk NGA describes begins where the face of the glass meets its glazing.

Drainage does not close the path either. NGA adds, “The presence of weep holes is recommended but is also not sufficient to overcome the risk of improper cleaning materials coming in contact with the edge of glass products.” The sentence is about which materials reach the edge, and it treats weep holes as a good feature that still leaves that risk in place.

The second seal gets a sentence of its own. NGA writes: “Exposure to certain chemicals may affect the sealants of insulating glass units and the surface of decorative products.” It follows with a line about time: a unit's longevity may be negatively affected by exposure to certain chemicals.

Two limits keep that line honest. First, the passage names no chemical. It tells readers to “Contact the supplier for additional recommendations and cautions,” and among NGA's own DO items is to be aware of and follow the glass supplier's specific cleaning recommendation. Which products a particular unit's sealant tolerates is the supplier's to say.

Second, nothing in the documents cited here says a cleaning keeps a seal sound or adds to a unit's life; NGA's line is a caution about materials only.

Impact windows add a second edge. NGA writes that “The plastic interlayer in laminated glass is generally exposed around the periphery of the window glass; cleaning fluids and their vapors must be kept away from this area.” Its examples of materials that may cause harm to laminated glass “include, but are not limited to” bleach, or other solutions containing sodium hypochlorite, acids and ammonia.

Impact windows are built with laminated glass, as PGT says of its own hurricane windows and doors, so overspray carrying any of those materials is a question about the edge of the glass. How cleaning an impact window compares with ordinary glass is argued in whether impact windows can be cleaned like regular windows.

One window maker's care guide turns the edge risk into a routine. The PGT, CGI and WinDoor instructions say: “Clean and rinse each window or door individually to prevent cleaning agents from permeating for long periods of time.” The reason sits inside the sentence. Time is the variable, and one window at a time keeps it short.

The same guide names what stays off its windows, screens, doors and hardware entirely, including “Petroleum-based products, abrasive or caustic cleaners/solvents, and hydrochloric/phosphoric acid,” with the warning that these improper tools may void the warranty and/or damage the products. It also gives owners a drainage task of their own: routinely inspect and clean the weep systems so the window drains as designed.

Solution and rinse water applied to the outside run down the glass and frame, and an open window or door is one more place they can reach, which is the reasoning behind closing windows before a cleaning.

Fog between the panes sits inside the sealed unit, out of reach of any cleaning. PGT, CGI and WinDoor write: “If you see condensation between the two layers of glass in an insulated window, the airtight seal has probably been broken, and the glass will need to be replaced.”

That sentence says what the fog means, not what caused it. Whether anything in particular broke a given unit's seal is a question for the window maker or the glass supplier, and this page does not answer it for any window. Why panes go cloudy on the inside of the unit is its own answer, in why windows turn cloudy between the panes.

Fog on the outdoor or room-side face is a different thing: the same guide describes it as condensation from temperature differences and says faulty windows do not cause it. Which face a haze sits on, and what an outside pass reaches, is sorted out under whether exterior window cleaning is enough.