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Expert: - 12/15/2009


Question
Hi Robert, We are experiencing a numerous amount of scratched glass after we clean windows. We are a post construction cleaning company. These windows are full of over spray paint and drywall compound used for taping amongst other debris We wet the glass with a glass solution( hot water and detergent for most) then we scrape off grime with 'professional window cleaning blades' but somehow we experience scratched glass occasionally. If we use fine wool maybe superfine0000 will it be as effective as scrappers? with the steel wool superfine 0000 will it be most likely not to see scratched glass? Is there any other  methods we can use other than scrappers? any other tool ? or cleaning solutions ?

Answer

Scratched Glass
Joe,

Drywall mud dust is messy, but won't hurt your windows. On the other hand, sand from cement will damage your windows if you don't remove it properly. Also cement on windows will damage the windows almost every time!

You are now 'enrolled' in my Window Cleaning 101 class. For your specific needs, please carefully read the paragraph below that starts with a warning.

Make sure you have a good window cleaning squeegee. You'll need the kind used by window cleaning professionals, not the kind used to clean automobile glass. You can find a professional window cleaning squeegee at a Home Depot or similar store. Unger and Ettore make these squeegees and are the name brand most commonly found. Also, make sure you use a new rubber blade as an old blade is sure to have nicks and cracks in it and will leave streaks on your windows. If you can't change the rubber blade in your squeegee, you don't have the right kind of squeegee.

Next you need a good window cleaning solution and a lint free cloth. If you do have some hard-to-remove object stuck to your windows, you can use triple fine steel wool or a new safety razor to remove any hard to remove residue.

About steel wool: Steel wool is graded by its abrasive properties. You will be able to tell what kind you have, from grade 1-4, by the zeros on the packaging. Do not use "0" or "00" grade steel wool as they are too coarse. On the other hand, "000" or triple fine and "0000" steel wool will work just fine. I would recommend the triple fine as "0000" will quickly crumble and make more of a mess than it is worth. Also never use rusty steel wool. The reasoning behind all of this is based on the Mohs scale. Mohs rates the "hardness" of a mineral, in this case silica (the main ingredient in glass) as opposed to iron (steel wool in this case). Look it up if you want to know more about this, or just trust my 20 + years of experience.

WARNING! Most window glass found in homes today is "float glass" and is processed by highly trained individuals in a plant that has high standards. Some glass, though, is tempered glass that comes from temperers that have little regard for the public, including those in the construction cleaning industry. Professional window cleaners, like your self,  are constantly finding tempered glass in residential and commercial applications that have fabricating debris baked into the glass. This debris is sometimes microscopic and is only discovered when a window cleaning razor (and sometimes steel wool) is run across the glass. When this happens and fabricating debris is present, the debris will break off, get caught under the razor or steel wool and then cause micro fine scratches in the glass. Remember, this almost always happens only if the glass has been tempered. Tempered glass is typically used in areas where there is a danger of the glass breaking. For example, it should be in all glass doors, and in large plate glass, like picture windows. If you are unsure if your glass is tempered or not, you can look in one corner of the glass for a small sandblasted logo that is supposed to be applied by the temperer.

Now for the window cleaning solution. Water is a great solvent. If you add a few drops of dish washing detergent in a pail of warm water you have your basic window cleaning solution. If the windows have any oily residue on them, and you will sometimes find this in new construction, that needs to be cut with ammonia. The correct proportions of these ingredients? Less is better! Use about 1/2 teaspoon of detergent to 5 gallons of hot water. If you use the ammonia, you will only need 1/4 cup to 5 gallons of water. In my humble opinion, this works far better than the "blue stuff"! Add your detergent to your water, not the other way around or you will have far too many bubbles. What kind of dish washing detergent? It doesn't really matter. My personal favorite is Dawn or Joy.

Now all you need is a lint free cloth. You can use the micro fiber cloth if you want. There are other kinds that also work well. I personally like huck towels that can be ordered from a window cleaning distributor.  

The method to clean the window is to dip a sponge (or brush) into the 5 gallon of window cleaning solution and "scrub the window with it. (By the way, there is a special tool made for this, a T bar, but you don't really have to have it.) For any hard to remove spots, just break out the steel wool or safety razor while the window is still wet. It is recommended to use these tools in one straight pass followed by the next straight pass. In other words, don't use your razor or steel wool as though you were buffing the window in circular or back and forth motions. If there is any debris on the window that kind of motion will only catch the debris and cause it to scratch the windows.

Finally, holding your professional squeegee vertical, wipe a clean, dry swath across your window, wiping the squeegee dry after each pass. On the following pass and thereafter, overlap your swaths by 1/4 of an inch and finish by detailing with your lint free cloth.

You may find it helpful to pre-detail by using your cloth to wipe around the top and sides of the wet window before you squeegee.

These are basic and simplified directions. There are more finer points that I can share with you if needed.

Without looking at your problem, my guess is that you are experiencing a problem with fabrication debris! (See warning above.) Whether or not you are indeed having this problem, I would suggest you read all the information at Dan Field's site: http://www.stopscratchedglass.com/

Let me know how it turns out.

Sincerely,

Robert Lamb
Window Masters
www.mywindowmasters.com

Robert Lamb

Expertise

I'm happy to answer any questions you have regarding the cleaning and restoration of your windows. I can also view your pictures via email and give you advice on what you can do yourself and what needs to be left to the pros. I can also give advise on scratched glass, how to repair it & what caused it. Pressure washing and gutter cleaning are other areas of expertise.

Experience

Over 20 years in the window cleaning industry, owning and operating two window cleaning companies, Rob's Window Cleaning http://www.robswindowcleaning.com and Window Masters http://www.mywindowmasters.com and http://www.robscleaningservice.com

Organizations
IWCA, window cleaning network, chamber of commerce

Publications
"Window Cleaner" magazine

Education/Credentials
International Window Cleaning (IWCA) training on man lifts, awning cleaning and window cleaning.

Awards and Honors
Voted best window cleaner in Western Kentucky.

Past/Present Clients
Applebee's, Cracker Barrel, CVS Pharmacy, Dairy Queen, Dollar General, Edward Jones, Enterprise Rent A Car, Ethan Allen, Fashion Bug, Fazoli's, FYE Music, GNC, H&R Block, Hardee's, Hot Topic, Kentucky Dam Village, Kroger, Logan's Roadhouse, Market House Museum, O' Charley's, Radio Shack, Rafferty's, Remax, Sirk & Co., Stanley Steamer, State Farm, Steak N Shake, Talbots, The Buckle, The Gap, The Outback, Toys Are Us, Victoria's Secret, and hundreds of others.

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