To find out, I contacted Alan Noah of Titan Laboratories. Here’s what I learned:
Dish soaps, like Dawn or Joy, are degreasers made up of almost 100% surfactants, so they have a lot of suds. (More on that in a minute.)
As Alan explained, “Surfactants are wonderful little two-headed creatures. One head loves water and the other hates it. So, when you get them wet, they go crazy.” While this is great for cleaning fabrics because the surfactants move through the material to loosen dirt, it’s bad for glass.
The problem comes when you mix surfactants with calcium (i.e., hard water) because they create a soapy scum. “Chemical blenders know this so they add a foaming agent, such as sodium lauryl sulfate, to produce artificial bubbles or foam. That’s supposed to make you think it’s working.”
However, what you really get is a blend of the soap scum mixed with the calcium, in turn creating a sludge-like goop that fills the microscopic pores on the surface of the glass and slowly destroys window tracks.
These microscopic pores are created during the glass-making process. When glass is manufacturered, it has to cool down from 2800°F, and this is done through a process called “floating.” The glass “rides on a river of molten tin.” As glass cools, it shrinks and solidifies. The bottom side of the glass is perfectly smooth, but the top side has microscopic pits and pores. This is where dish soap’s cleaning “goop” collects.
Glass Gleam 4 (GG-4), on the other hand, not only avoids creating goop, it removes it from the pores, leaving window cleaner, longer.
“The glass now sparkles as it bounces the light freely off the many pits and pores, like a diamond. And since the dew doesn’t cause the window to weep, it stays clean for a very long time.”