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.

PROBLEM: Oxidation
SOLUTION: Mild Chemicals & Abrasives

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.

   » More Information

Stain Removal and Window Restoration


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.
  • Note: With glass that is poorly heat treated, be extra careful not to scratch the glass when scraping. Click here for more information about scraping. It is smart to have your customer sign a liability waiver before doing any scraping on a job-site. Click here for our scraping liability waiver

Variety is the key:

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.

In terms of liability: Click here for more information about scraping glass. It is smart to have your customer sign a liability waiver before doing any scraping on a job-site. Click here for our scraping liability waiver.

Frame restoration:

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.

  • Diamond Magic Stain RemoverDiamond Magic Stain Remover
    Diamond Magic, made with real diamonds, removes water spots and polishes surfaces.
  • A1 Hard Water Stain RemoverA1 Hard Water Stain Remover
    A1 Hard Water Stain Remover is used in the removal of silicas, cement leach, acid rain and mineral deposits from glass and the other surfaces. A nontoxic water based biodegradable SOFT CREAM.
  • Bio Clean Water Stain RemoverBio Clean Water Stain Remover
    Bio Clean Water Stain Remover is used for easy removal of hard water stains, cement leaching, sprinkler stains and runoff. No harsh chemicals or unpleasant odors.
  • CC550-WinsolCC550-Winsol
    Winsol Crystal Clear 550 helps to eliminate alkaline residues, exhaust particles, chemical and mineral deposits, water spots and the runoff from brick, concrete and mortar.
  • OneRestoreOneRestore
    OneRestore formerly Safe Restore removes water hardness and pollution stains, and mineral and metal oxide stains. It is an effective coating remover and safely cleans glass and anodized aluminum.
  • Hard Water Stain Remover-SorboHard Water Stain Remover-Sorbo
    Sorbo Hard Water Remover is developed to quickly remove hard water stains, building run-off and sprinkler stains from window and other glass surfaces like shower doors.
  • X19 Glass Cleaner & Restorer - ABRX19 Glass Cleaner & Restorer - ABR
    X-19 Glass Cleaner removes hard water marks, stains caused by run-off from unsealed masonry, airborne pollution and acid rain haze that causes oxidation to glass.
  • Ettore Water Spot RemoverEttore Water Spot Remover
    Cuts through hard water deposits and soap scum. Ideal for windows, glass shower doors, mirrors, porcelain, and chrome. Abrasive-free.
  • AMAZ Water Stain RemoverAMAZ Water Stain Remover
    A-Maz Water Stain Remover is a deep cleaner that penetrates the surface to remove all all stains; restoring the glass, metal, or porcelain back to the original quality.
  • Fields Scale RemoverFields Scale Remover
    Fields Scale Remover loosens and removes scale, deposits, and cement from exterior windows. Dissolves efflorescence and mineral deposits from stucco rundown on glass.
  • Cement-OffCement-Off
    Titan Cement-Off is an environmentally friendly liquid to remove cement products such as cured concrete, stucco and grout.
  • Tin Side DetectorsTin Side Detectors
    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.
  • Mr. HardWater Stain RemoverMr. HardWater Stain Remover
    A1 Hard Water Stain Remover is used in the removal of silicas, cement leach, acid rain and mineral deposits from glass and the other surfaces. A nontoxic water based biodegradable SOFT CREAM.
  • Sheer Glass Water Stain RemoverSheer Glass Water Stain Remover
  • Scrub Pads, Steel WoolScrub Pads, Steel Wool
    Scrubbers for getting construction cleanup and water stains off of glass.