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What is the best way to remove hard water stains?

Are you struggling to get rid of stubborn hard water stains from windows, or dealing with unsightly etching from your (or someone else’s) previous attempt? We can help with that! In this article, we’re going to simplify this process and talk all about the tried-and-true methods of hard water stain and etching removal. But, before we get into the best methods and chemicals, we need to talk safety: Before using any of these chemicals, keep in mind that some are highly corrosive. Make sure that you research and understand the chemical you are using, and take the necessary measures to protect yourself. This means wearing the proper PPE, or personal protective equipment, including acid-resistant gloves, safety goggles, masks, long-sleeve shirts, full-length pants, and protective footwear. Your environment must also be well-ventilated, as breathing in these chemicals can be damaging. Furthermore, it is important to understand the surfaces you are working on. Some of these chemicals are not suitable for every surface, so it is important to follow the links provided, check out their web pages, and read the resources and instructions attached to those products. We at WCR want you to work with confidence and as much knowledge as possible to ensure you’re working safely for yourself and for your employees when removing hard water stains and etchings. Now, let’s dig into it!

Hard Water Stain Removal Methods

When it comes to hard water stain removal, there are two great methods. You can either:

1. Dissolve them with a hydrofluoric acid-based chemical
2. Abrade them with a polishing system.

But sometimes, when ridding of these spots, we come into the challenge of etching. Luckily for us, there are ways to avoid this. So, before we get into the best products to use, let’s discuss some of the science behind how inconvenient and unsightly etching occurs in the first place, and what you can do to avoid it.

Etching: Why it Occurs & How to Avoid it

There are two main causes of etching on glass:

1. By attempting to remove hard water stains with hydrofluoric acid on the tin-side of the glass, in turn, creating tin etch haze
2. Acid rain or oxidation from other environmental pollutants

The most common type of glass produced in the United States is called float glass, which is mainly composed of silica, lime, soda, and recycled broken glass. Once blended together, it is then heated in a furnace to form hot liquid glass, then flowed onto a molten bath of tin. An extremely thin layer of tin will remain - it will be so thin, it won’t be visible on the glass, but chemically, will be very difficult to work with. Hard water stains occur and are so difficult to remove because the minerals in the water contain calcium carbonate from mortar, cement, bricks, or limestone, and is mainly composed of silica. Since these droplets are mainly composed of silica, they literally bond to the glass. Luckily, there are ways to determine which side of your glass has the tin on it, avoid creating unwanted etching, and decide which product is the right one to clean it with.

Finding the Tin Side of the Glass

When this tin side is treated with hydrofluoric acid, that is when etching, or more specifically, tin etch haze, will occur. This is why it is always important to discern which side of the glass you are cleaning. You can do this by shining a battery-operated UV lamp such as the CRL Tin Side Detector, and find out in no time if you’re facing the tin-side of your window, and whether to use hydrofluoric acid on it or not. When shining your UV light on the tin side, it will glow. When shining the UV light on the air side, you won’t see anything, meaning you can use the most effective method, hydrofluoric acid, to clean the hard water spots without fear of etching the glass - and worse - disappointing the client. Furthermore, it is important that you always do a spot-test on an inconspicuous area of the glass with any chemical you plan to use, just to make sure it won’t cause any mishap.

Removing Pre-Existing Etching

If etching already exists, a polishing compound such as the American Building Restoration Glass De-Etcher can remove some of the hydrofluoric acid burn stain from the glass. This can be applied with a buffer or an angle grinder which is recommended for use with the Glass Renu Scratch Removal System.

The Best Products for Hard Water Stain Removal

There is a multitude of products out there made for removing hard water stains. Some products come in powders, some in pastes, and some in liquids, all having different levels of corrosivity for different levels of stains. We’ve tested them out in the field, and are here to let you know which ones are the best of the best.

Powder Stain Removers

Powder stain removers can be fantastic for ridding of mild hard water stains, and are best used with water, and a towel or sponge. The JFlint Mr. Hardwater Micro Mineral Powder is an acid-free, chemical-free, non-toxic, eco-friendly cleaner. Not only does it work on glass, but it’s great for removing stains on tile, stone, and metals throughout your home. Just be mindful if you're in direct sunlight, because being a powder, it can dry quickly and cling to the glass. Give the glass a good rinse, and it’ll be good to go.

Paste Stain Removers

Less corrosive Ettore Scrub Off is a liquid-paste stain remover formulated to remove milder hard water stains, calcium deposits, lime scale, and soap scum. It is safe to use on glass, tile, porcelain, and windshields, and works best when applied with a sponge. Made with real diamond dust, Diamond Magic Stain Remover is an aggressive stain removing polishing compound. You can apply this by hand, sponge, towel, or with a high-speed buffer. The safe and effective yet aggressive BioClean paste stain remover can be used with towel, sponge, or light abrasive. Renew surfaces to a spotless clean with this unique formula. This all-in-one cleaner can remove soap scum, mildew, rust, limescale, iron, and even paint overspray. It can also be used to clean, seal, and maintain surfaces like shower doors, tubs, windows, tiles, marble, granite, brass, stone, porcelain, brass, aluminum, stainless steel, and more! The less-corrosive paste stain remover Unger RubOut removes everything from hard water, to lime, to cement stains, without causing any damage to the surface. Use this with an abrasive, such as steel wool or a XERO White Scrub Pad, and watch the mess disappear. The Titan A-1 Hard Water Stain Remover removes and cleans mineral deposits, acid rain, cement leaching silica, screen burn, soap scum, oxidation, scale, lime, corrosion, chalking, and rust, and works beautifully with steel wool. With its non-acid formula, it can be used on most surfaces including glass, porcelain, fiberglass, aluminum, stainless steel, and everything that is washable.

Liquid Stain Removers

The most corrosive Winsol Crystal Clear 550 Glass Restorer is made with hydrofluoric acid, and will absolutely remove those hard water stains. With this chemical it is extremely important that you use the proper PPE to protect yourself. Another effective stain remover that utilizes hydrofluoric acid is the commercial grade EaCo Chem OneRestore. This chemical works to dissolve rust, oxidation, screen burn, and hard water stains with ease. Like the Winsol Crystal Clear 550, always use this in a well ventilated area and be sure to perform a small spot-test in an inconspicuous area to make sure it would not harm the glass. Liquid stain removers like these are perfect to use in a spray bottle, which is also helpful for when you need to perform your spot-test. Having fresh water closeby is also essential to clean up spills, rinse glass thoroughly after using these products, and just in case your skin comes in contact with it.

Polishing System

The aforementioned Glass Renu Scratch Removal System is a great tool for when you need to get the job done with haste. Wonderful for buffing out the most stubborn stains, this polishing system can be used in tandem with any of these products listed.

Want to learn more?

Now that you’ve learned about these wonderful hard water stain removers, you may be curious to discover even more fantastic products that will help your clients’ homes shine - and we’ve only just scratched the surface! For product reviews, discussions, information, and more: Check out our informative YouTube Channel Get advice, share tips, or just talk shop on our Window Cleaning Community Page Shop professional-grade window cleaning chemicals and more at WCR! And most importantly - get out there, believe in yourself, work hard, and don’t forget - the rewards of this career are bountiful - so, have fun! As always, if you have any questions, Window Cleaning Resource has technical support available to you 24/7. Not only are our technicians friendly and knowledgeable about our products, but most of them own or have owned their own window cleaning business for decades, and are open to fielding any question you may have about window cleaning. Talk to you soon! From, Your friendly professionals at Window Cleaning Resource Window Cleaning Resource How Can We Help You Today?