Artificial Hard Water Spots

Hard water spots are otherwise called mineral deposits. They are based on various metal salts. Also silicates. It is the silicates which are the most difficult to remove. These are based on a silicon chemistry, and will bond exceptionally well to a glass surface. Usually the only acids that will dissolve silicate deposits are those that chemically attack the glass surface itself. Here we are talking about acids such as hydrofluoric, sulfuric, and ammoniumbifluoride. Many of the hard water spotting problems out there are due to silicates. These come from ground water, and from concrete efflorescence (or leaching). The micropores in the surface of concrete building facades soak up rain water (which is acidic). There the rain reacts with the minerals in the concrete bringing them into dissolution. The now mineral laden rain water leaches out of the micropores, down over the glass. When the sun comes out the drops evaporate, leaving behind the minerals that were formed when the rain reacted with the concrete. These silicates are usually very high in silicon. I remember seeing an elemental read out one time of the various elements present in a sample that was scraped off a window. The silicon spiked off the page. The reason I am going over this information is to show what type of stains are chemically much more likely to really stick to the glass. This is the type of stain that we would like to duplicate on a microlapped surface in order to test various glass protectants to see which one works best at keeping the spots from locking on. Simply put;...silicates. Now if one takes what is called water glass (sodium metasilicate), and mixes only several tablespoons in a quart of water, it is possible to create your own silicate deposits. All you have to do is microlap a window that gets direct sun, then sprinkle your formula on the glass. Spots will form when the water drops evaporate. At times they will stick instantly. Or some time in the hot sun might be needed. Either way, you have created what I arbitrarily call "artificial hard water spots".

Henry Grover Jr.
Glass Tech Consulting
gtcnews@hotmail.com