How to Clean Windows With Grids and Divided Lights

If you are trying to clean windows with grids and the glass keeps drying streaky in the corners, the method is probably not the problem. The grid type is. Twin Cities houses carry three completely different kinds of grid, and one of them cannot be cleaned at all. Work out which one you have and the job gets a lot shorter.

Three kinds of grid, and how to tell them apart

Put a fingernail against the grid bar from the inside and you can sort this out in a few seconds.

• A true divided light has real glass on both sides of the bar. Every small pane is its own piece of glass, bedded in putty or held by thin wood stops, and the grid pattern lines up exactly between the inside and the outside.
• A snap-in grille sits against one large pane. Run a fingernail into the joint where the bar meets the glass and you will find a seam, and the whole grid is usually a single lightweight frame that lifts out of the sash.
• A grille between the glass lives inside a sealed insulated unit. You can see it and you cannot touch it from either side, and the glass stays flat under your hand as it passes over the bar.

Housing stock around here splits along the same line. A lot of the 1920s houses in Macalester-Groveland and Highland Park have divided lights in the upper sash and a single pane below. Newer construction out in Woodbury is usually one big pane with a snap-in grille or no grid at all.

The grille between the glass needs nothing

Start with the good news. A grille sealed between two panes never gets dirty. It sits in the dry space inside the insulated unit, and no dust or spray reaches it. Clean the two outer glass surfaces as you would any window and you are finished.

If that inner grid looks hazy or there is moisture in the sealed space, that is not dirt and no cleaning will touch it. That is a failed seal, and there is more on it in the piece on winter condensation.

Divided lights are towel work, and the putty needs care

A squeegee needs a clear run of glass to work. On a sash broken into six or eight small lights there is nowhere to start a stroke, so divided lights are towel work.

Wash each pane with a damp microfiber rather than a soaked one, then dry it with a second clean towel, pushing into each corner with a fingertip inside the cloth. Corners are where this job fails. Water left sitting in a corner wicks back out onto the glass while the pane dries and leaves exactly the streak you were trying to avoid.

The part to be careful about on an old sash is the putty. The glazing putty bedding each small pane is decades old, often cracked, and on some houses it is barely holding. Soaking it does it no favors, and running a stiff scraper along that joint will pop pieces of it out. Keep the cloth damp rather than wet, stay off the putty line, and if putty is already crumbling away from a pane, that is a glazing repair and not a cleaning problem.

Snap-in grilles should come out

If the grid turns out to be a snap-in grille, take it out before you start. Most of them sit in a shallow channel and come free with a gentle flex of one long bar near the end. With the grille out you have a plain large pane, a squeegee works normally, and the grille itself can be wiped flat on a towel on the table.

Two cautions. Go slowly, because the plastic or thin aluminum gets brittle with age and a cracked bar does not glue back together invisibly. And keep track of which grille came from where. The upper and lower sash of the same window often take slightly different sizes, and sorting them out afterwards takes longer than the cleaning did.

Where it stops being a weekend job

Inside, divided lights are a reasonable Saturday project. It is slow, but there is no ladder and nothing to damage if you stay off the putty. The general method is the same one in the guide to cleaning windows without streaks, just repeated many more times per window.

The outside is where it changes. On a story-and-a-half with divided lights up top, the exterior of those small panes is ladder work at an awkward angle, and on most older houses the storm window has to come off first. That is the half people usually hand over, and it is where a high pane count really shows up in the time. Exterior glass on a Gleam Team window cleaning is done with purified water from a water-fed pole that reaches up to forty feet, so the height is handled from the ground, though a wall of divided lights still takes longer than the same wall in big single panes.

If you want a real number for your house, say how many of your windows have small panes when you ask for a quote, or pick a time on the booking page. It changes the time more than anything else about the job.