The two most common minerals that cause the hard water spots on your windows are known as calcium and lime scale. As fresh rain water passes through the ground, calcium, lime and many other minerals are naturally dissolved into the water. The ground water is then tapped into for irrigation and drinking. When the hard ground water comes in contact with a window, such as through a sprinkler, it will eventually evaporate leaving hard water spots behind. Each time this happens a new layer of mineral deposits are accumulated resulting in a hard, crusty shell that is nearly impossible to remove.
Sprinklers are the most common reason for hard water spots to form on windows. This is usually an easy fix. Adjust the position of the sprinkler head so that it doesn’t continuously hit your windows. Sometimes the water pressure on the system can be adjusted as well.
Often the wind blowing the sprinkler water up onto the glass can be the problem. In this case you will want to clean off any existing build up and then apply a special coating to the glass. Glass coating products coat the surface of the glass, which creates a protective barrier. This barrier will not prevent the water spots from sticking, but it will prevent it from becoming permanently attached. The mineral build up will then wipe off with ease.
If you decide to wash the building with a garden hose or power washer, make sure you use a window squeegee to remove the water before it has a chance to evaporate.
In the window cleaning industry, mineral deposits are defined in three stages. Each stage determines the amount of build up, ease of removal, and possible damage that may be found.
Stage one consists of 1-2 light coatings of deposit. This can be easily wiped or rubbed off with a rag or sponge using regular soap and water. At this time no damage has been detected.
Stage two is when the deposits have built up to the point where they have a white but still transparent look. You can see tiny scales starting to form on the glass. At this point, it may be difficult (but not impossible) to remove with normal scrubbing. A window scraper and acid base or light abrasive glass cleaner may be needed to completely remove the scales. Still, no permanent damage has been detected.
Stage three is when the deposits have built up over a long period of time and create thick, hard, scaly shell. With this amount of build up and time, the deposits may etch into the pores of the glass, and can be baked on by the sun or both. You will know the damage has taken place when the window scraper or cleaners will not remove the scale build up. At this point, the window will have to be buffed out using a special buffer, with abrasive window buffing pads. This process should be carried out by a professional to avoid additional damage to the glass.
Tip: When using any cleaners or tools on glass, always follow the directions and test in a corner first. Also, seal the surrounding surfaces with plastic to prevent further damage.
"Spot-X Hard Water Stain Remover"