| What is self cleaning glass? | | | | Does it always work? |
| Self cleaning glass is glass which has been thinly | | | | Jeff Howell, exploring the pros and cons of self |
| coated with titanium dioxide, an inorganic pigment that | | | | cleaning glass in The Telegraph (June 27th 2005) |
| is used in a variety of products including sunscreen | | | | concluded that self cleaning glass is "self-cleaning as |
| (reflects UV rays), toothpaste and as a whitener in | | | | long as it doesn't get dirty." |
| white paint. | | | | He contends that reality is often somewhat different |
| To put it simply, it uses a dual-action process in which | | | | to theory. Whilst self cleaning glass surely performed |
| organic dirt is broken down by daylight and is then | | | | well in laboratory tests the same conditions seldom |
| washed away by rain, thus making it easier to keep | | | | apply in real life. How often do upstairs windows, |
| clean. | | | | sheltered by lintels, arches and eaves get really |
| More about how it works | | | | soaked by rain? If rain is lashing against one side of the |
| Self cleaning glass works by two processes: | | | | house, the other will surely remain relatively dry and |
| | | | therefore unwashed. |
| 1. Photo-catalysis - the action of sunlight onto the | | | | Jeff interviewed one manufacturer of self cleaning |
| surface of the glass eats away dirt. It does this by | | | | glass who admitted that their product is only |
| absorbing the UV component of sunlight which then | | | | "self-cleaning" as long as it is regularly hosed down |
| breaks down any organic material on the surface of | | | | with water, and even then it works best when the |
| the glass. | | | | water flows slowly down an incline - such as on a |
| 2. Hydrophilicity - instead of forming droplets that run | | | | conservatory roof - rather than straight down, as on |
| down the window in rivulets leaving streaks, the | | | | normal vertical windows. |
| rainwater spreads out as a continuous sheet washing | | | | So.... no easy answer to your window cleaning |
| the glass clean. | | | | problems I'm afraid! Best stick with the professionals. |