PROBLEM: Hard Water Stains SOLUTION: Chemicals and Abrasives
Hard water stains occur when sprinkler water hits
the building or rainwater travels over concrete or
a precast surface of a building and carries tiny
particles from that surface onto the window. After
the rainwater dries the mineral deposits are very
hard to remove. Acid rain and sprinkler stains are
of the same nature due to the high concentration
of minerals present in the water. Much like
Oxidation, mild chemicals, abrasives and some
scraper usage will take care of most problems.
Oxidation, also known as etching, hazing or
screen burn, occurs when metals around windows
(frames, screens, etc.) are exposed to rain or
humidity and deteriorate causing oxidation. This
oxidation runs down the glass and penetrates (or
clings to) the glass. Mild acids, like Crystal Clear
550, or abrasives like Sörbo Stain Remover (often
combined with fine steel wool) are often all that’s
required to remove the oxidation.
To see all of these products in action, watch our video about window restoration with window cleaner Craig Aldrich on our video page
Mildest to strongest stain removers:
A1: A white, pasty product. Removes basic hard water stains, but will not remove silicate deposits. Basic stains include those made of calcium and magnesium. It may remove some oxidation stains, mild screen burns, and similar stain problems.
MDR: More of a liquid product, versus A1. Removes basic hard water stains, but will not remove silicate deposits. Basic stains include those made of calcium and magnesium. It may remove some oxidation stains, mild screen burns, and similar stain problems.
RubOut: A liquid/paste product. Similar in many ways to A1 and MDR. Removes basic hard water stains, but will not remove silicate deposits. Basic stains include those made of calcium and magnesium. It may remove some oxidation stains, mild screen burns, and similar stain problems.
Bio-Clean: A green, pasty product. Has a mild, gritty texture to it. Slightly tougher than the above three products. A popular product among window cleaners.
Sorbo Hard Water Stain Remover Powder: Pour powder on a wet white Scrub pad and apply directly to the glass. Just as you would any of the liquid paste/products above.
X-19: Oxalic Acid. One of the milder acidic cleaners. Not as strong as a Hydrochloric or Hydrofluoric Acid.
OneRestore: Hydrochloric Acid. Make sure you wear gloves with any type of harsher acid. Also deemed a restoration detergent. Sometimes, it is best to spray this product onto the glass. When you spray on the chemical, it helps keep the chemical in a concentrated area when working. This is a smart technique when working on hot conditions. You do not want to have these harsher chemicals dry on the substrate. Note: if used in this manner, beware of hazardous inhalation hazards.
CC550: Hydrochloric and hydrofluoric acids. Make sure you wear gloves with any type of harsher acid. Warning this will smoke/cook float glass. The chemicals in this product react with the tin in the glass. You can detect the tin/air side of the glass with a UV light, the digital tin detector or the Tin Side Detector Lamp. CC550 will work safely on the air side of the glass. It is recommended to test the product on a small area of the glass to make sure you will not "cook" it before applying this product to the entire window. You want to work relatively quickly with this product if you are in hot areas.
How to use these products:
Apply product to wet white pad and apply to glass in a circular motion. Work in 1 ft squares. You want to work relatively quickly with this product if you are in hot areas.
If necessary, you can also use a steel wool pad on the area, scrubbing the chemical into the glass After scrubbing with steel wool, use a scraper to remove the oxidation deposit from the window. Scraping gets below the stain. Since glass is a porous material, the longer the stain has been on the glass, the harder it will be to remove from the substrate.
It is good to keep a few different types of stain removers in your truck. Sometimes, one product will work better than another on a specific project. Also, you can use a milder stain remover on the upper portion of the window pane - where the oxidation and silicate deposits are less concentrated - and use the harsher products only on the lower portion of the glass to remove the tougher stains.
A word on pricing your job:
When doing a stain removal job, remember you are not only cleaning the windows, but you are also restoring the glass to its original state. Remember, you are incurring the extra costs of the stain removal products and your time. You also have the skills and knowledge of how to remove these stains and the added liability of using these harsh chemicals on the glass. All of these are excellent reasons to charge a special fee for window stain removal and restoration. This isn't a simple, "straight" clean, so price your job accordingly.
You can also offer the additional service of frame restoration to the customers. OneRestore is an excellent product to restore the window frames. Spraying the chemical on the window frame will help keep it from getting on the window panes themselves. Scrub in the chemical with a steel wool pad, rinse, and dry. Note: If spraying harsh chemicals, beware of hazardous inhalation hazards.
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Some chemicals, like Hydroflouric acid (found in CC550) will smoke or cook the tin side of float glass. These tin detectors will identify if the side you are working on is the tin or air side of the glass.