Hazy/Fogging Studio Glass Double Windows

[Zenon Marko]

Hello, everyone -

I hope all are doing well during these challenging times, and finding solace in music.

Studio (downtown NYC) has been in lockdown, of course. Working alone here. Meanwhile I have noticed that the custom-installed studio double-glass windows have gradually been fogging up and becoming hazy. In the photos, this haze is most evident as an aura, when looking at the lights through the windows.

This haze/fog does not look like moisture (to me, at least), unless of the very finest sort. Also, the amount of haze remains consistent with temperature variations. Therefore, I suspect that this is the result of some sort of outgassing, some very fine particulate or chemical residue. It looks finer than normal household dust, as I cannot discern individual particles. Perhaps it's a film that became visible over time from whatever cleaning product the glass installers might have used. There should not be much temperature variation between the spaces on either side of the windows. Could it still be just water condensation? Other theories welcome!

General studio construction info is in this thread:
https://www.johnlsayers.com/phpBB2/view ... =2&t=20706&

We built the windows as follows:

- laminated (not tempered glass)

- closed-cell neoprene setting blocks

- 2 different thicknesses of glass: 3/8" + 1/2"

- parallel, straight (non-angled) glass panes

- straight-through (coupled) wood framing

- no outgassing sealants used (e.g. silicone); possible use of butyl tape (not noted)

- 1x1 wood (painted black) all around perimeter, both sides of glass, to hold glass in place; with 1/8" closed-cell neoprene (self-adhesive) on glass contact side to seal

- desiccant: CR Laurence Molecular Sieve Adsorbent MSD5

- desiccant installed in CR Laurence spacers between panes

The glass was crystal clear when installed. The hazing is already occurring and worsening over time. This is a problem as one has to look through 4 total panes (this window, and another one between the stairwell and live room, visible in second photo below) to visually communicate between control room and live room. (The other double-window is also experiencing this hazing, but to a lesser degree thus far).

We plan to have contractors remove a pane on one side, clean the windows, and re-install. Before undertaking that delicate task, I would like to understand the cause and determine a remedy, to prevent this from recurring, if at all possible.

Questions:
- What might be happening here?

- Has anyone experienced this kind of haze/fogging before? (It looks very different from any photos of fogging I could find online, which typically look much more obviously like water)

- Could the adhesive on the neoprene be outgassing?

- Could the paint be outgassing?

- Could any cleaner used on the glass be the problem?

- Recommendations on re-installing?
- What type of cleaner to use?
- Presumably room should be cool and de-humidified when installing?
- Is there a better desiccant to use?

Any guidance would be much appreciated.

Best regards.

Studio Glass Windows fogging hazy (1).jpeg

View through Studio Glass window, with hazing/fogging

Studio Glass Windows fogging hazy.jpeg

View from opposite side through Studio Glass window, with hazing/fogging

Studio Glass Windows fogging hazy (3).jpeg

Construction of window framing on both sides, with self-adhesive closed-cell neoprene (1/8"?) between the frame and window on both sides.

[TomVan]

Zeno,
I feel your pain. My first big build back in 06 I ran into the same problem.
I was asked by a contractor friend at the time if I had done a proper dry out before installing windows and doors. I had not ( I was unaware of this process) But after thinking about job sites where I had seen heaters running at full blast for days turned a light on in my head.
Green timbers, sheet rock mud and paint all carry a significant amount of moisture/water. Close the entire building up water/air tight and the moisture has not place escape. My fresh air obviously didn't handle any of it. I ended up buying a dehumidifier and within a couple weeks I had removed over 35 gallons of moisture. Removed the glass, used windex to clean again. Ran the dehumidifier and heat for a week again and re-installed glass. Zero fogging after that.
Since then all the studio builds I have done, I blast the space with heat and dehumidify. Never a problem since drying out the space before glass.
Your space look Fabulous. Hope you're enjoying it otherwise
Peace
Tom

[Zenon Marko]

Zeno,
I feel your pain. ...I ended up buying a dehumidifier and within a couple weeks I had removed over 35 gallons of moisture. Removed the glass, used windex to clean again. Ran the dehumidifier and heat for a week again and re-installed glass. Zero fogging after that.

Thank you, Tom, for the excellent advice.
Did the fogging you witnessed look anything like the haze I have on my windows here? Or was it more obviously moisture dripping down?

Also, it's interesting that you first heat the space before reinstalling the windows. I would have thought to cool the space, since cool air holds less moisture...?

My (Daikin) HVAC system does have a "dry" mode which removes humidity, so I can utilize that as well.

Also, any recommendations on the cleaning spray to use on the glass? You mentioned Windex...but even that has some additives (fragrance, color). Presumably the less ingredients, the better, as any residue could lead to trouble. I don't recall what the window installers used.

In general, for glass, I use Method Glass+Surface cleaner...but even that has some additives.

Thank you again.

P.S. One more thought on drying the room: There is now a grand piano in the live room, which cannot be removed without disassembly, and it is recommended to keep it in a stable environment (temperature around constant temperature of 20°C and humidity between 40-50%). I'm not sure how dry the room has to be for the window install, but now I'm a bit concerned if drying the room may damage the piano...?

[TomVan]

Zeno,
It was more of a fogging/haze. Nothing dripping down.
Cleaning with ammonia and water 1:16 ratio is about the cleanest of chemicals you can use.
It is your call on the grand piano, I would call a piano manf. and ask if it would be OK for a week of dehumidifying the room.
I have acoustic guitars in my room and the same is recommended. They are all fine.
Hope that helped
Peace
T

[Zenon Marko]

Zeno,
It was more of a fogging/haze. Nothing dripping down.
Cleaning with ammonia and water 1:16 ratio is about the cleanest of chemicals you can use.
It is your call on the grand piano, I would call a piano manf. and ask if it would be OK for a week of dehumidifying the room.
I have acoustic guitars in my room and the same is recommended. They are all fine.
Hope that helped
Peace
T

Thank you again, Tom -
How dry do recommend making the room? I have a hygrometer to measure.
I shall speak with Steinway about the piano.
Just realized that perhaps a better option is to remove the pane on the other side of that window, in which case it's more critical to dehumidify the stairway area; I could keep the live room closed with a humidifier in there simultaneously to keep it at least 35% or so in that room.

Best,
ZM

[TomVan]

Zeno,
That actually sounds like a good plan.
I am not sure on measurements, but I would assume after your dehumidifier stops taking on water would be about right
Tom

[Zenon Marko]

Hello, all -

The common method of building studio windows (such as described by Rod Gervais in his book, and in this thread) involves applying glazing tape to the stops, on the side which will contact the glass.

- Should glazing tape (or some other tape, like adhesive neoprene) also be applied to the side of the stops which will attach to the the window frame? (Since wood-wood may not make an airtight seal)

- Should any caulk/sealant be applied also after the outside stops are in place, either at the stop-glass contact, or the stop-frame contact? Or at joints of the stops (where horizontal and vertical stops meet?

- Any recommendations on brands and models of caulk/sealant, whether butyl or silicone, and tape to use? CR Laurence perhaps? GE Silicone? We are very concerned to both achieve a proper seal, and to avoid using any substances which could cause outgassing (fogging/hazing).

Any advice appreciated.

[Zenon Marko]

Hello, all -

Just an update on this, and seeking opinions as well.

I have not yet had any work done on the windows yet. However, once winter arrived, the fogging seems to have largely resolved itself.

My theory is that outside air is leaking into the space between the panes, via the leaky interior walls of this building. Those spaces get extremely cold in the winter, so presumably warm humid NYC summer air makes its way into there in the summer. (I know this as we have various access panels into the walls and ceiling, and the air in those spaces is always close to outside temperature). I can't recall how we closed up the bottom of the window and whether there is a gap left between the two window baseboards or not. If there is, it would have been filled with neoprene rubber, but perhaps not airtight. I can't see the baseboard gap because of the desiccant strips inside the window cavity.

So: I assume in the warm weather when AC is operating, the space between the glass has the hot (or at least warmer) humid outside air, whereas the rooms have the cooled and dehumidified air thanks to the AC. So the glass will cool down, and moisture will condense on the inner surfaces from the humid air trapped in the cavity.

In the winter, the temperature situation would be reversed; air in the space between the panes would be cooler/colder, if anything, than the room air. Yet no condensation forms on the outside of the glass, presumably because in general the air is much drier in winter time.

The remaining slight haze may be some kind of dust or outgassing (off-gassing) residue. So I may still have to remove a pane with the workers and clean the inside; seal that inner area up better if it has an air channel to the building’s crawlspace air; seal it back in better. Best to do this now in winter when air is dry, so the air that will be trapped in the space will be as dry as possible.

If this theory is correct, then the goal would be to prevent humid air from getting trapped inside there again. I do notice some gaps have formed around the window framing, so perhaps that's how air is getting in. Perhaps first thing to try is just to seal up those gaps with sealant/caulk (perhaps Big Stretch) and see if the problem recurs in the summertime. If the problem does recur, then I would have to remove a pane and see how moisture is still getting inside (presumably the aforementioned possible baseboard gap).

Any speculations and advice welcome and greatly appreciated.

Best regards,
ZM

[gullfo]

definitely fix the obvious leaks in the windows and if possible you might open up the framing/jamb around the window to see if there are other areas of leakage and seal those.

[Zenon Marko]

Hello, all -

An update on this. During the winter the fogging disappeared! So I had contractors just seal up the outside blocking of the window once again, hoping that dry winter air would now be trapped in the window cavity.

Sadly, when the weather became warmer, and we started to use AC in studio, the windows have been fogging up again, and it's getting worse throughout the summer.

Presumably this means that external (by which I mean sourced from outside the rooms, i.e. from the wall cavities which are essentially filled with out door air) air is getting into the window cavity. That summer air is warm and humid; the air conditioned rooms make the glass panes cooler -> fogging.

Presumably fogging would not happen if the leak were only air from the rooms. After all, in that case, air temperature, pressure, and humidity should all equalize between the rooms and the window cavity. So I would not expect fogging in that case.... is that thinking correct?

If so then it looks like we will have to open up the windows, check and seal any leaks into the wall cavities, and close up again. Again, I expect this is best done in wintertime when air is less humid, and after dehumidifying the rooms as well, so that the newly trapped air in the window cavity will have lowest possible humidity.

Thank you for any further thoughts on this problem.

[gullfo]

more concerning would be mold growing in the walls because the exterior walls weren't sealed. one option would be to force low/no humidity air into the inter-wall space and draw it out to exhaust it.

[Zenon Marko]

more concerning would be mold growing in the walls because the exterior walls weren't sealed. one option would be to force low/no humidity air into the inter-wall space and draw it out to exhaust it.

Thank you for the suggestion...Do you mean as a one-time fix, or to do this periodically?
I assume you mean the former, and then seal up again permanently.

Still, if there is an unsealed gap in the window sill, permanently sealing that gap would require removing one of the window panes.

[gullfo]

i'd do what it takes to eliminate the moisture problem. otherwise venting the space would be the only way to ensure you're not trapping it and leading to a mold condition.