"bubbles" in window seals.

Inspected a 13 year old house today. There appeared to be “bubbles” on the rubber seal between the thermopane windows in many areas. Anyone see anything like this before?

The bubbles appeared to be more prominent on the bottoms and sides of the windows where the sun was more likely to hit. Tops and sides in shade didn’t appear to have the bubbles. It seems as if the rubber was bubbling from overheating.

I didn’t see any indications that the window seals were actually compromised, no fogging or condensation, etc., but my client was concerned that there is a potential problem in the making.

Any thoughts?

By the way, I couldn’t find any manufacturer’s name on the windows.






Writing what you see will help…a glazier probably knows.


Larry has pointed you in the right direction.

Note what you see and report it as such. You know at that point that something is wrong and you have addressed it. That is as far as you need to go.

I do have a little information that might help your interest to this toppic and hope it helps you out.

Foggy, or haze, beads of moisture running down between the panes. Any of these signs are indications that you have window glass with failed seals.

What are possible causes of seal failure? Water, ice and sunlight tend to deteriorate the insulation surrounding the glass, which will ultimately result in seal failure and condensation between the glass layers as well as non-approved glazing compounds and ultraviolet light beating directly down on the glass sealant. Builders grade windows are not designed to last.

**Seal failure occurs when the sealant between the two lites of glass breaks, subjecting the airspace to the surrounding environment. Since the sealant acts as the moisture barrier, if the seal breaks, condensation can develop in the airspace of the insulating glass window.

Premature seal failure is usually caused by one of three reasons:

  1. Poor design of the unit so that it will not pass the standard ASTM tests recommended by the Sealed Insulated Glass Manufacturers Association.
  2. Poor workmanship on an individual unit during fabrication.
  3. Poor frame design, which will allow the unit to sit in a high moisture environment.
    Hope this helps out.

Marcel :slight_smile: :slight_smile:

you’re almost home free. In this case, I’d report that I noticed it and have no idea as to the cause, and what if any action should be taken other than to seek a second opinion.

That particular window had the glass sealed together with a product known as Swiggle, over the years it didn’t hold up well and I do not believe it’s used anymore.

When you see the bubbles in the Swiggle seal failure usually is not far behind.


Swiggle Seal is TruSeal´s first all-in-one flexible spacer introduced to the industry in 1979.

We have out grown this I believe, but possible to encounter.

Marcel :slight_smile: :slight_smile: :wink:

This is what I had written.

*"Observed “bubbles” on the rubber seals between most of the double hung windows. *

*This was notable because the bubbles appeared to be more prominent on the bottoms and sides of the windows where the sun was more likely to hit. Tops and sides in shade didn’t appear to have the bubbles, the seals were smooth. It “appeared” as if the rubber was bubbling up from overheating, although the inspector could not determine if that was the cause or not. *

*It should be noted that there were no indications in the double hung windows that the window seals were actually compromised, ie, there was no fogging or condensation, etc, and the inspector could make no definite determination whether or not the bubbles actually constituted a problem. *

Clients may want to have this evaluated further, however, by a qualified window specialist."

I also told the customer that I would be researching it further (as an “added value customer service”) and would let him know if I found out anything further. Looks like Peter may have a little more info.

Thanks Larry, Marcel, Keith and Peter for your input!

Peter, do you have any more info or links about the problems with Swiggle Seal? After doing a google search, I’m not finding any problems reported with it like the bubbles I’ve seen.

These windows are from 1993.

Mark, I don’t have much info. other than being a window installer in a previous life. I remember that the swiggle had allot of problems with heat build up, it would literally bake the swiggle until it eventually cause a seal failure.

If the window are from the early 90s it may be the original swiggle, as far as swiggle still being on the market, I’m not sure, if it is I hope they changed it.

I think Marcel’s link will help you more, good link Marcel!