I would say it's a bit interesting and intriguing. I'm also curious what actually makes this phenomenon happen and can some measures be taken to slow or alleviate this issue? Is it merely an optical illusion with "Light" playing the major role?

Craig Aldrich
Sparkle Window Cleaning - Canyon Lake, CA

It's definitely not lighting. From what I understand, there are always tiny lateral cracks whenever the surface of glass is compressed. In tempered glass, these lateral cracks eventually turn back up to the surface, causing tiny chips of glass to pop out. I don't think you can prevent that - the glass is just rebounding from being indented.

These [the cover photos in the May issue of American Window Cleaner Magazine] are some of my first pictures - before and after the scratch grew.

I actually saw this tempered glass scratch grow suddenly. About 45 minutes after I took a picture of this new scratch, I was looking at it with my shop microscope to see if had changed.

This segment hadn't changed much at all – but then it actually popped while I was looking at it. I saw it grow, and I believe I heard it pop – a tiny "poink" sound.

This is going to change everything – no one is trained or hired to stare at a window for an hour to see what happens.

Gary Mauer
Window Cleaning Network - Oconomowoc, WI

If it were only lime - calcium chloride - it would be nothing drastic. That would come off with something as simple as simple as household vinegar, (Acetic acid.)

But there would be a lot of silicates in concrete runoff, and those are the toughest to dissolve. Don't waste your time on an acid that doesn't dissolve silicates. Here's a link to post on the Window Cleaning Network back in 2000 - where Dan Fields, Henry Grover, and yours truly chimed in - and Paul Duffer's name was dropped.

Word was, only a hydrofluoric acid would dissolve the silicates. It's not the "safe" chemical you were hoping for, but in all the years we've been archiving WCN email, that has been the only chemical mentioned. Unless you go with an abrasive polishing system, which I think would be considered safer.

In a 2008 article in USGlass about the silicates problem, authored by Paul Duffer, he says that when rain causes concrete runoff onto glass, and water beads up, then dries off, silicates become concentrated into water spots. The silicates are insoluble as soon as they are formed, a condition that's "undaunted by normal cleansing procedures."

Duffer goes on to say, "In fact, these materials are so difficult to dissolve that hydrofluoric acid is required for cleansing in laboratory experiments."

Duffer suggested taking great care with polishing compounds to avoid scratching the surface. If you're using hydrofluoric acid, the tin side can be a problem, because the HF could etch the tin.

Gary Mauer
Window Cleaning Network - Oconomowoc, WI

When introducing a new chemical to your inventory, always follow the instructions on the MSDS (soon to be SDS) and on the container.

Whatever you choose, read the directions on the label and make sure to wear the proper Personal Protective Equipment as indicated on the MSDS.

Jon Arreguin
C-THRU Window Cleaning, LLC - Saint Paul, MN

We plan on full PPE but want to ensure that the results are productive. What do you mean by tin side?

Calvin Barr
Ever-Clear Window Cleaning Ltd. - Kelowna, BC, Canada

Modern float glass is flat and smooth because it was made by pouring molten glass on molten tin. Because of the tin, there's a microscopic amount of tin on the bottom side of all float glass. Doesn't bother anything unless someone uses hydrofluoric acid on that side. If there's any tin left, the tin will be etched by the HF, and you'll have a grayish stain. If you are using hydrofluoric acid, you can protect yourself a couple of ways. One way is to check for tin with a device called a tin side detector, or a strong ultraviolet light. (The tin side glows gray in UV light.)

Another is to use a waiver. With CC 550, I think you can download a sample from either Winsol or the distributor. The waiver says the client agrees to live with any etching that may occur.

Gary Mauer
Window Cleaning Network - Oconomowoc, WI

A waiver is always recommended, for any restoration work.

Jeff Scott
Green Window Cleaning, LLC - Sun Prairie, WI

Is it fair to ask if they noticed the windows on the way in?

Gary Mauer
Window Cleaning Network - Oconomowoc, WI

Have you ever had a job where you worked alone? Have you ever had a job where you worked outside? Are you afraid of heights? Can you comfortably climb a ladder? If yes, how high? What is the best job you ever had? Why?

I like to ask a few basic questions. These are things I want to know, and the way that the candidate answers them gives me a chance to get to know them a little bit. I'm more concerned with the way they're answered than the answer itself.

David McKeen
Western Reserve Window Cleaning - Kent, OH

There are books on how to hire the right employee at the library that will give you all the ideas and questions you need to ask. Here is a good interview question, "At lunch your partner drank vodka. What do you do?" Most people don't know how to answer this question.

Ron Friman
Expert Window Cleaning – Hawaii - Chicago, IL

We do a fair amount of retail storefront work for several national janitorial companies. The IVR system is pretty straight forward. There is a phone number provided on the work order, the crew calls that number from the store's phone and enters the work order number and PIN (also provided on the work order), and logs in and out. It's basically just a way for the janitorial company to make sure we have been at the store. It's quite easy and straight forward.

Almost all of the national janitorial companies we work with require IVR participation.

Tena Liudahl
Mr. Squeegee Window Cleaning Inc - Bismarck ND

IVR helps the service company track progress for billing purposes and assures that the contractor actually showed up. Basically, the contractor calls the IVR number from the store phone and gives data to a machine. I find it to be a nuisance though I understand the reasons behind it. I would charge for the time spent - plus or minus 5 possibly frustrating minutes.

Stephen Hallett
Sonlight Window Cleaning - Little Rock, AR

I mistakenly thought SDS was just a name change when I first heard. This looks like a fundamental improvement in hazard communication.

As you say, employees to be trained by December 1, 2013. The transition to SDS will take longer - June 2015.

Gary Mauer
Window Cleaning Network - Oconomowoc, WI

Here is some really good info from OSHA on the new system; all the ins and outs straight from the horse's mouth, so to speak.

Troy Nelson
Xtreme Cleaning - Janesville, WI