Is it really possible to defog an insulated glass window?

Disclaimer: The views and opinions expressed in this article are those of the author. Examples of analysis performed within this article are only examples. They should not be utilized in real-world analytic products as they are based only on very limited and dated open source information. Assumptions made within the analysis are not reflective of the position of any one but the author.
Window with clouded insulated units
Window with clouded insulated units

I regularly get calls from customers that have cloudy insulated units. Most of them ask one of the following questions:

  1. Does the whole window need to be replaced?
  2. Can you replace the glass only?
  3. Can you remove the “fog”, “dirt”, “moisture” from the inside of the existing glass?

Before I comment on the above questions, I will define a typical insulated unit.

The majority of insulating glass units consist of two lites of glass enclosing a hermetically sealed air space.The lites are held apart by a spacer around the perimeter. The spacer contains a moisture-absorbent material called a desiccant that serves to keep the enclosed air free of visible moisture. The entire perimeter of the assembly is sealed.

Window with visble moisture
Window with visble moisture

A window is considered “foggy” or failed when there is visible moisture between the glass.

  1. Does the whole window need to be replaced?  In most cases, no.  There are some windows that have very specialized framing or glass that needs to be replaced by the original manufacturer.Can you replace the glass only?
  2. Can you replace the glass only?  This it what can be done in about 90 -95% of windows.  It can usually be done with only minor finish touch-up required on the frame.
  3. Can you remove the “fog”, “dirt”, “moisture” from the inside of the existing glass? Not cost effectively.   Several times a month,  a customer tells me that someone they know had someone come out and drill some holes in the glass and clean it out. I always tell them to call that person and ask them who did it.  The response is they forgot who or that they are out of business. There is no company that I am aware of in the Chicago area that does this process.

I found several patents describing the process.

System for alleviating in-vault condensation in double-glazed windows

Method of treating a glazing panel

I will now critique the process and show that even if it would work, it is not cost effective or practical.  In fact the Canadian company that owned and used the former patent is no longer in business.

  1. Both methods require drilling holes in the glass. It is a messy process and it is impossible to do in tempered glass.  All doors and many other locations require the use of safety glass.  Most safety glass is tempered. The latter patent recognizes this issue and then describes a method in which a hole is drilled through the side of the frame through spacer.  There are many problems with this solution.

 a. This could possibly damage the structural integrity of the frame.        b. You now are drilling through the metal band and desiccant.  This      will cause some to fall between the panes of glass.                                  c. Not all windows can open to get to the side.

2. After the holes are drilled, a “cleaning solution” is to be inserted in the unit.  This really confounds me as I fail to understand how this will be able to clean the entire inner surface.  It also will get the metal spacer wet and the desiccant will absorb it.  As anyone who as ever cleaned windows knows, this will most likely leave streaks.

3. If you get past the above problems, you have the issue of how to plug the holes.  Imagine how the window with numerous lites that leads this post would look with all these little holes in the glass.

There does not seem to be a company in the Chicago area that does regularly does this work.  This indicates to me that either the process does not work, or is not a feasible business!