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alexz 08-02-2006 05:57 PM

"Defogging" double-pane windows .... a gimmick??
I posted on another home forum about removing the condensation between the panes in my two 51" x 61" picture windows. I bought the house in December when there wasn't much condensation, but now it's pretty bad. The people who responded to post noted that I'd have to have the glass replaced entirely. That's looking to be around $700 - $800. But I saw a Yellow Pages add that advertised a company that could defog windows. So I started reading about it on the internet (which always requires scrutiny and skepticism) and there are a number of companies saying that, in many situations, windows can be defogged.

Here are a few:

Here's an article in the Ottawa newspaper about it:

Is this defogging process truly possible? effective? Anybody tried it?

BTW, the person who used to own this house is no longer living and I can't find out who installed the windows. AFGD is stamped inside the window and I talked to the local dealer of this glass manufacturing company. They said I'd have to find the contractor who installed the windows to initiate any warranty that may be valid on the windows .... basically a dead end for me.

Hoping for an inexpensive solution, but trying to be realistic....

Alex Z
Knoxville, TN

manhattan42 08-02-2006 06:56 PM

You need new windows.

Nothing else to be said.

joed 08-07-2006 09:05 PM

The reason there is fog inside the window is because the seal is broken. Even if they defog it, it isn't a thermal window anymore. You need a new window.

fhivinylwindows 08-11-2006 04:58 PM

All it takes is a pin hole to leak moist air into your window. One small pin hole in your 51+51+61+61 inches. If you need a 3rd opinion, get a new window.

Buy one with a lifetime glass warranty.

jgiedt 08-11-2006 06:36 PM

Yes! Window defogging does work, and well.
First of all, you do not need a new window if just the insulated glass unit is foggy. There is MUCH more to be said! You can make the repair by replacing the insulated glass unit alone and retain the sash and frame assembly, or you can use the defog repair method you mentioned.

Second, moisture inside a window does not mean the seal has broken. A seal *may* have broken or it may not. The secondary seal of an insulated glass unit is not impervious to air. This is one reason why most every insulated glass unit has a moisture control product inside- a dessicant to absorb the inevitable moisture that will enter every ig during its lifespan. Often the moisture is present because the insulated glass has reached its moisture threshold; there is more moisture inside the glass than the dessicant can effectively absorb and hide.

Take an ice cube and place it on the "clear" window glass of similar age and design for between :45-1 min. You just lowered the dew point at that spot. Now wipe away the moisture from the outside of the glass. You'll probably find that there is also a moisture spot inbetween the glass too that you cannot wipe away. WoW! Your "clear" window has moisture in it! Where is the seal broken though? Hmmm?

Third, when properly defogged using the methods of the companies you listed in your question, the moist air has been replaced with a still, dry air space and the insulation ability of the window has been greatly improved from the wet condition and will insulate very near its newly manufactured state.

I've got six repaired windows in my own home and will continue to use this defog repair method to maintain my insulated glass as the rest of them fail. It has worked great!

If you do not have a company in your area to make this repair, then the intermediate cost option would be to have a glass company replace the insulating glass in your window. Buying a whole new window is an option, but may not be necessary unless you are unhappy with the window style or function.

'hope this helps.

MikeR 12-15-2006 01:03 PM

How long defogged?
Hi jgiedt,

You mentioned you have six windows in your home that were defogged?

How long have they held up so far?

I have a similar problem in my house with some large (and large $$ replace, uuggh...) windows.


Mike R
Granite Bay, CA (sacramento)

jgiedt 12-16-2006 07:12 AM

I did them in phases, as they fogged. The first three or four has been 3 years. The others are a year or so. No problems. They look great. Simple science on gas in enclosed containers plus the fact that dry air insulates. Why would they all of a sudden NOT hold up? I like it!


Originally Posted by MikeR (Post 26990)
Hi jgiedt,

You mentioned you have six windows in your home that were defogged?

How long have they held up so far?

I have a similar problem in my house with some large (and large $$ replace, uuggh...) windows.


Mike R
Granite Bay, CA (sacramento)

oberon 12-16-2006 06:37 PM

fixing windows
Condensation between the lites in an IGU is a cosmetic issue. Unless there is argon loss or there is corrosion of the LowE coating, there is no difference in energy performance between an insulating glass unit with condensation and one without condensation between the lites.

There is a common misconception that all dual panes are gas filled with something other than air – and technically air is a gas of course - when in fact less than half of dual pane windows manufactured today have an argon (or other) gas infill between the lites.

There is very little likelihood that an older dual pane window ever had a gas infill because until the past few years very few dual pane IGU's were filled with argon. And many of those that were filled probably lost the argon fill years ago due to migration thru the (mostly obsolete) materials that were used to seal the unit at that time.

Gas escaping from the interior of the IGU does not cause fogging. Fogging is almost always (with a few rare exceptions) caused by moisture penetrating the seal between the two glass panes.

If anyone is interested, I can make this very long and technical, but for a quick answer, repairing a “failed” IGU is never a DIY project.

There are a number of companies out there that are advertising that they can clear up foggy IGU’s. In some cases they can give the appearance of “fixing” the IGU in the right circumstances.

The condensation between the lites is almost always caused by an excess of moisture that has entered the space because of a blown seal. The IGU “repair” does not take into account the seal failure and does nothing for it. The IGU repair (or “fog-out”) folks simply arrange for the IGU to evacuate the excess moisture by drilling holes in the glass and placing a one-way valve that works with natural heating and cooling cycles to replace the air within the IGU airspace. Basically, air comes in thru the breach in the seal and goes out thru the one-way valve.

Again, I can get much more technical on how and why this works – although the “fog-out” guys (and if “fog-out” happens to be a trademark or use name of a particular company I am not aware of it – if so, then I am using it generically and mean no comment for or against a particular company or product) have all sorts of interesting claims on their various sites – often exaggerated and a few that are simply incorrect – concerning the performance of a typical IG window system.

Still, the basic concept is sound – with certain restrictions it may be possible to clear up the condensation between the lites of an IGU using the method that they promote. Again, they don’t do anything particularly earth-shattering other than allow air movement between the lites which allows the moist air to escape from between the panes – much the same as a single pane acts with a storm window.

NickD 03-30-2008 10:11 AM

" You need new windows."

Thought this was a DIY board with real tips, am a retired engineer, not one of those guys that sat behind a desk, have a complete metal, wood, and electronics shop and like to do everything myself. For one thing, a means to beat the credit card companies and the IRS, if some guy is charging you 70 bucks an hour for something you can do yourself, you actually end up paying over twice the price as you are using post tax dollars, and if you have to pay interest, just another slap in your pocket book. I built my own home in 1970 while carrying on a full time job, with good buying and hard work, had it paid off in three years. Also do all my own vehicle work, but do have my Ram reflashed now at the dealer, not about to pay $7,500.00 for the equipment required just for a particular brand of vehicle. Think this reflashing is crazy.

Another thing that is crazy is argon filled windows, I had to sell my own built home because of a job change and purchased my present home in 1985, it's paid off, been for, for some time, take good care of it, but also sharing your problems with foggy windows, I have six out of 45 panes that are foggy, was only four last year, two more this year.

Saving 60 t0 70% off the cost of new windows doesn't sound very good to me to have some guy come out to my home and make a mess out of it. Drilling a couple of holes is no big deal, I have the tools to get those holes to within +/- 0.0001" if I have to but they refuse to sell me those check valves. Then they claim to use a proprietary cleaning solution, what? Soap and water? Maybe even denatured alcohol, I have both air compressors, shop vacuums, and even a good sized vacuum pump and can experiment if need be. They talk about silica jel, I don't see that stuff in my windows.

And I don't throw away my dirty dishes either.

I feel like I was ripped off, not only by Koebe & Koebe that has no solutions, you are out of warranty, twenty years ago, they would sell direct to me, now it's strictly going to some lumber company that doesn't even have a parts book. They tell me to bring a window in and leave it there for a couple of weeks until the no-nothing rep comes around, how stupid do people think I and the rest of us are? And then to have to pay a huge markup on that stuff.

We are sure getting ripped off by these tax credits and DOE regulations, I checked into the R value of argon filled windows as opposed to solid insulated double thickness glass, the difference was infinitestmal. Maybe a guy would save a couple of bucks a year in fuel cost, but after the warranty would have to pay thousands and thousands of dollars for window replacements. And real insulated glass is neither recommended nor eligilible for a tax credit. Something is very fishy here, of course, real insulated glass won't leak.

Then there is the building inspector to deal with, believe the main requirement to get these jobs besides being a brother-in-law to the mayor is to have an IQ less than 1.998. Ran into this about replacing the hot water heater, wanted to install one of these new high effeciency forced ventilated heaters. First I can't install one in the basement because the snow may getter higher than the PVC vents, but why to you permit forced ventilated furnaces in the basement? Duh!!! And why can't I raise these cheap pipes a couple of feet? Besides with my overhangs, no snow every gets near the house anyway. You just can't do that. But after finding about all the problems with these heaters, extra electrical, failure of the control mechanism, but to top everything else off including one a one year warranty on the Chinese made electronic garbage, they only save 20 therms per year at an initial installation cost of several hundreds more.

Where is the savings in either these water heaters or argon filled windows? It's stupid and downright criminal to the home owner, and what about the guy with a 30 year mortgage and every increasing property taxes and interest rates? Work your can off just to end up with a pile of junk?

There has to be a way where a guy can clean and reclaim these windows, after 23 years, they still look new, except for that stupid fog in between the glasses. If I find anything, and I am looking, will let you know, already thought about painting them black.

HandyPete 03-31-2008 05:00 AM


I live next door to a IGU manufacturer. He's going to get a big question from me today! My first thought is to change just the IGU. I see folks going into the shop and buying new units everyday. Expensive? not supposed to be. You can easily change the unit yourself with just a few hand tools. Check the phone book or Internet and find a glass distributer like PPG. Don't go down to the local glass shop or window company!

-- pete

kylemfk 03-31-2008 07:17 PM

just order the IGU from your local building supply house. Pop of the glazing beads cut out the old one pop in the new one, replace glazing bead w a little caulk and goodnight irene

oberon 03-31-2008 07:38 PM


Originally Posted by NickD (Post 112149)
" You need new windows."

We are sure getting ripped off by these tax credits and DOE regulations, I checked into the R value of argon filled windows as opposed to solid insulated double thickness glass, the difference was infinitestmal. Maybe a guy would save a couple of bucks a year in fuel cost, but after the warranty would have to pay thousands and thousands of dollars for window replacements. And real insulated glass is neither recommended nor eligilible for a tax credit. Something is very fishy here, of course, real insulated glass won't leak.

A 100% argon fill increases the thermal performance of an IG unit by 16%. A 50% argon fill increases the thermal perfomance of an IG unit by 8%.
It's a straight linear relationship.

Argon fill has nothing to do with moisture between the lites of an IG unit, windows with no argon can and do have seal failures.

If I may ask, what is solid insulated double thickness glass or real insulated glass?

Mr Chips 04-05-2008 08:48 AM

a friend of mine had one of these franchised services come to his house and do some windows. this was in spring of last year, by christmas time they fogged up worse than before.

he would have been better off just covering the glass with $50 bills, still wouldn't be able to see out, but the view would have been much better

jupiter2000 04-07-2008 06:47 PM

just had the guy here...
just had the guy here associated with

first off, if its diy then i suggest you do so... kinda a rip off at $300 to do two skylights!

using a dremel type tool the guy put holes on the inside corners of the window (dependent of the size and ability to clean) then he sprayed some cleaning solution in and then a rinse. spray it in the top and suck it out the bottom.

"the installation of the 'micro' DefoggerTM valve and seal"
then he covered the wholes with clear plastic stickers! and the "valve" is another one of these stickers with grating holes... which will definitely keep larger insects out!

now, if this actually works then i will be happy but wish i paid less of course. i should have asked the guy how long it would take him before i agreed cause $300/hour is definitely a rip off!

i think given what everyone has said then i suspect whether this approach works or not is complex. for example, is the seal busted, how much of a leak does one have and is the leak allowing air from inside in or from outside.

i suspect it may be worth a try instead of replacement. if you diy and it fails then you are just out the time taken.

NickD 04-19-2008 07:49 AM

I checked with a local glass supply company, if I bring my casements in, he will measure them order the glass, and on the second two mile trip will install them for an average price of 100 bucks a window using new argon filled gas.

He will do that while I am waiting so I don't have to worry about rain if I pick a clear day. Windows are easy to snap out. Sounds like a much better deal than having some guy come over and drill holes.

I told him I have Koebe & Koebe windows, was to the factory and was told the frames were encased in epoxy. He said he has done many windows like that before and can replace the glass in about twenty minutes. Have no idea what his trick is, but willing to risk 100 bucks and find out, if okay, will bring the others in. I know he was in business for over 30 years.

Was questioning this

Paul Lacey
Chief Development Officer
Crystal Clear Window Works USA, LLP
475 Craighead Street
Nashville, TN 37204
Tel: 615-385-0240 ext 102
Fax: 615-385-0304

Never got a quote from them, can't do it myself, but looks like it could be a waste of both time and money.

Has anyone found replacement argon filled glass on the web? Koebe tells me they buy it but wouldn't tell me where. I tried a search, found plenty of new windows for sale, but never just that double glass with the aluminum frame.

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