Glass Cleaning Frequency Research

Hi All,

I spent the better part of 2 hours tonight trying to find research about how often glass should be cleaned, and what is at risk if it isnt. We all know from experience the different things that can be deposited on the surface, but I would like to point my customers to at least one article. I found a good amount of window cleaner sites that state it can damage the glass if they aren’t cleaned enough, clean at least every 6 months, etc. Where did this information come from? Any thoughts? I know we have a niche industry, but there has to be something out there. Thanks in advance for the thoughts!

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Pella had maintenance instructions on their site, telling owners how to care for their windows and frames. Those instructions included frequency of cleaning and painting.

All I could find was that they recommend inspecting once a year and cleaning as needed. I’m more looking for either statistics (e.g. leaving environmental contaminates for 6 months or more increases chances of staining by x amount given the standard urban environment) or even general statements about the long term affects of not cleaning glass, by an authority other than a cleaning company.

Best person to ask is @Henry

Because all glass surfaces are not the same and all types of dirt, debris and contaminates are not the same there is no one time period that fits all situations.

Glass has a durable surface and telling a customer that it will be damaged by not cleaning is a far stretch to prove or sell.

I find the appearance of a clean or dirty window is far easier to sell.


To my customers I am the authority. When they ask, and many do, “how often should I get my windows cleaned?” I tell them. I don’t always say the same thing and whatever I say is, to them, the voice of authority.

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I tell my waterfront customers every quarter. I tell my more inland customers every quarter to every six months. I have some that live near the interstate, every quarter is barely enough.

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If you have ever cleaned windows that have not been cleaned in YEARS, you’ll quickly see how they can get damaged. All of those environmental pollutants dig their way into the glass.

If you, as the glass cleaning expert, can’t convince someone that cleaning their windows at least once a year is to their benefit and prolongs the life and beauty of their windows, then why should you honestly care? They just don’t care enough about their property, so neither should you, IMO.

I don’t think any of the car manufactures tell you how often you should wash your vehicle, but I’m sure if you never washed it and then tried making a paint claim, they would laugh you out of the dealership.

When it’s dirty, you clean it. Seems like common sense.

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Thanks to all that responded! I knew it was a long shot because of all the variables, but I was hoping there was some statistic that someone knew about that I didn’t. I have seen something to the effect of, if you don’t have your glass cleaned at least every 6 months then there can be Damage Done to the surface of the glass. I usually see this on window cleaner sites with no reference, but I was hoping for some actual statistical evidence that I could cite. My storefront and residential customers usually consider me the authority, but as I’m looking into commercial, such as hotel and apartment buildings in my area, I have been finding that they know very little to nothing about window cleaning. I’ve had multiple locations tell me that they’ve never even had a window cleaner ask to clean their Windows! They usually just have a pressure washer. I know there are some companies in the area that do clean buildings of that size, and even though we have 750,000 in the greater suburban area, there aren’t enough high-rises I’m guessing to support a good number of larger businesses that can handle large buildings. I have actually had a good amount of interest in people having their larger buildings clean, so hopefully that will translate into some business in the next month or two. I was just hoping to give people a more complete picture of what it takes to care for their windows.

I have been curious about this also. Glad you asked!

I would say that, that statement is not correct. More often than not when a surface is exposed to things like hard water, it is not the surface that is damaged it is the deposits of minerals after the water has evoporated, damage to the glass would be scratches, etching, pitting none of which can be caused by general circumstances. Not having the glass cleaned for a prolonged period of time will not damage the surface of the glass, all it will do is make your job more difficult and more detailed to obtain a perfect result.

When customers ask me how often the windows hould be cleaned, I tell them its about personal preference and the location of the home in regards to pollutants, I would recommend that at least once per year, however I go on to say many of my other customers usally get their windows cleaned every six months if not every quarter, in most cases they will book a six monthly over once per year they clean freaks will go with quarterly.

This is true. You could have your customers do a self test in the kitchen; tell them not to wipe the counters, faucets, sink, don’t clean the microwave, oven, or refrigerator for 6 months to a year - then they can clean all of that and see that neglected maintenance does in fact make a huge difference. While they are at it they can neglect the bathroom too. Kind of puts it in perspective for some folks when they can see on a daily basis the difference that it makes. Windows are easy to ignore, until they can’t ignore them any longer.


Not a similar comparion.

You compared clean windows which is visual to clean bathrooms and counter tops which are health issues if not cleaned. Also these surfaces like counter tops and floors are more porous and suffer much more damage from neglect. Totally different materials and conditions.

A window exposed to direct sunlight, gets very hot. Especially if there is something on or near the surface that pulls in more sun, then reflects it. (Such as a black curtain or dark colored tint)
Heat may be something that assists you in cleaning (such as hot water) but heat also softens the surface to let pollutants dig in harder.
Glass is not a smooth surface, even though it may feel that way to the touch. It’s porous too, unless someone spends the time to polish it down (then it loses reflectivity). Glass is also sensitive to chemicals of certain natures, and it’s relatively soft.

Like anything else, if you don’t clean it, it sure won’t look good, like the day it was installed. And by look good, I mean it doesn’t look good because of the degradation of the surface. Yes, you can bring it back to life with enough effort, but whats the point? I don’t avoid washing my vehicles so I can just repaint them in a few years.

Whatever, dirt is dirt.

There are technical publications that discuss the natural weathering of the surface of soda lime (window) glass. High humidity coupled with high heat will absolutely degrade the glass surface. Most times however this cannot be seen. It does increase the likelihood of the glass to hold onto any stain organic or mineral. It also makes the glass much more prone to scratches. And can be felt when the glass is dry by lightly running a dry fingertip across it. To demonstrate do the finger test on an old storm window. The outer surface will be rough and the inside will be smooth. Windows should be cleaned and sealed with a product like Nanovations NG 1010. As for further documentation GANA has produced several papers on this topic. Also the Glass Committee of the IWCA has been working on the science of glass surfaces for many years now. Wishing you all the best in your research. I strongly suggest joining with the Glass Committee.



@Steve076 thanks for posting! I usually tell my clients something very similar for frequency, but I was hoping for some more info that I could educate my larger clients with that I knew was accurate.

Thanks @Henry, this is great! It gives me something at least that, though as not specific as I would like, it will better educate my customers and make me more of an authority in their eyes. So from what you and others have said, it seems that from normal air bourn pollutants the surface of the glass with not be degraded. Would, say, a pressure washing chemical that has dried and redried cause more damage the longer it is left on the glass? I will look into the committee.

My point is, there are much better ways to sell your services rather than stating the glass will be damaged.

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While I am a strong advocate of using glass sealants to protct window surfaces especially exterior glass and low e coats, I do agree with jhans about marketing. Most people just want clean windows. Probably the best way to land a job is to show them what a clean window really is by doing just one. When they see how beautiful a sparkling clean plate of glass is you shouldn’t have any trouble making the sale!


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