'fogged' double pane windows

[Ted S.]

Re: 'fogged' double pane windows

FWIW - the chances of me contacting somebody to replace windows is probably 4 orders of magnitude lower than getting a correct answer, or 10,000 times greater than the intelligence of the person who suggested that

I feel bullied.

[Mark Parlee]

Re: 'fogged' double pane windows

Ted

just so Randy doesn't say to me "I Told You So"

It's all good; this is how we learn. We even learn about human nature on this site.

[Randy Bush]

Re: 'fogged' double pane windows

Randy
On the building science portion of the forums we have been a little more accommodating of this type of conversation.
We have been able to address and advise on some problems that have educated the masses that choose to participate.

Mark, I am sorry if I was out of line here on this , thanks for informing me of this.

[Mark Parlee]

Re: 'fogged' double pane windows

Randy

No problems; You were not really out of line.
The building science part of this has been a little more lenient with regard to the formalities.

We have had some that were educations for all of us as we figure a particular problem out.
Occasionally we get bit and this looks like one of those times. He did bring up an interesting point but was not satisfied with some of the answers.

[Oberon]

Re: 'fogged' double pane windows

Quick answer for the pros here since the OP's reply was totally uncalled for.

When soda-lime glass is being constantly exposed to moisture, that moisture will eventually begin to leach sodium ions from the surface of the glass which then forms sodium hydoxide (an alkaline) that attacks the silica in the glass and you have etched glass.

Or something like that....

[dgbldr]

Re: 'fogged' double pane windows

Thanks Oberon. I learned something new today.

[Mark Parlee]

Re: 'fogged' double pane windows

Yes
That's why these threads are valuable
Oberon
do you have any links to this info

[hdrider_chgo]

Re: 'fogged' double pane windows

Quick answer for the pros here since the OP's reply was totally uncalled for.

When soda-lime glass is being constantly exposed to moisture, that moisture will eventually begin to leach sodium ions from the surface of the glass which then forms sodium hydoxide (an alkaline) that attacks the silica in the glass and you have etched glass.

Or something like that....

Interesting- why would that same effect not occur on the surface of single-pane glass? Some of it has been exposed to moisture for more than 100 years... Or maybe the rain washes off the sodium hydroxide as it forms?

Good to see you back around, Oberon.

[NW Architect]

Re: 'fogged' double pane windows

Ditto the welcome back, Oberon!

[Oberon]

Re: 'fogged' double pane windows

Yes
That's why these threads are valuable
Oberon
do you have any links to this info

I agree, I learn a ton here reading different threads. Unfortunately, I often come to the conclusion that I wish that I had read the thread before I had done something....

And to a link: Not off hand, but I did try a couple of google searches after reading your reply and found several links to sites that did discuss glass degradation or pitting or etching. The most interesting one (yeah I am a nerd) was by the folks at "Sabre Pack". Among other things they sell glass interleaving powder which is used to prevent glass while in shipment or storage from being damaged. They are very well known and respected in the glass industry.

There were a number of links to glass restoration as well but they mostly dealt with antique glass - often pre-nineteenth century glass. But the mechanism of damage hasn't changed all that much.

And of course I forgot to bring the link with me when replying to your post...however Google search for glass, sodium hydroxide (spelled it right that time), etching, etc will bring up some interesting sites.

[Oberon]

Re: 'fogged' double pane windows

Interesting- why would that same effect not occur on the surface of single-pane glass? Some of it has been exposed to moisture for more than 100 years... Or maybe the rain washes off the sodium hydroxide as it forms?

Good to see you back around, Oberon.

Thanks!

Good question. Actually it does occur on old glass, in fact in some locations it is quite common, but it is just so gradual (and not happening on every lite out there), that people simply don't notice it that much. And, that type of etching/damage that is seen in IG or dual pane windows can be really obvious because of how it is formed.

The primary reason that it is worse in dual pane applications is due to constant exposure. When moisture invades the airspace of an IG unit, it can't dry out. Once the desiccant is saturated that moisture is going to be causing damage in the space between the lites.

And as an aside, hardfwater stains on glass are not the same as etching even though they can look similar. Hardwater staining is usually a build up of calcium carbonate on the glass surface - but hardwater staining can lead to etching.

Anytime glass is shipped next to glass (on a rack for example) it needs something (interleaving)between the individual lites to protect them. Interleaving might be paper, cork pads, or probably the most common interleaving, a "powder" of some kind.

Interleaving protects the glass from damage. Glass on glass without protection is going to scratch. The glass may also trap moisture between the lites if exposed and that trapped moisture will very quickly lead to etching of the glass surface. I have seen more than a few racks of glass ruined after exposure to moisture (or condensation when glass is shipped in the cold and then goes into a warmer, highter humidity environment) and not being separated quickly enough to allow it to dry. And if the glass is etched in that way, then throw it into a cullet bin because it is ruined. There is no economical or practical way to save it.

The Sabre Pack folks that I mentioned in the previous post manufacture an interleaving product that is used to keep the lites from touching on the rack to help prevent scratches and in some cases also to protect the glass from etching if it is exposed to moisture.

Some interleaving powders consist of tiny lucite beads treated with adiptic acid (most common) or boric acid (less common), or some other acidic substance. Using the acid-based substance counteracts the alkalinity from moisture and prevent formation of etching on the glass surface during shipping and storage.

Hope that makes sense even if I did (as usual) wander way past the original question!

[Oberon]

Re: 'fogged' double pane windows

Thanks Oberon. I learned something new today.

you are welcome, and believe me I have learned a ton from reading you posts as well.

[Oberon]

Re: 'fogged' double pane windows

Ditto the welcome back, Oberon!

Thank you and ditto my previous response!