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b “INSULATED GLASS FOGGING”
Of 64 units installed in a house built 29 years ago, about 14 have “fogged”. By removal of one pane with a heat gun and thin knife, the interior can be cleaned, then resealed with Butyl/polyurethane/polysulfide mix and some dessicant, which is usually successful.
About 5 of these units could not be cleaned since the “fogging” was literally etched into the inside of the panes.
Does anyone have any information about what causes this etching – could it be bacterial, outgassing effects, global warming, or untraviolet b;yproducts of whatever.
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Replies
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Art,
Is there a purpose to trying to salvage thermal units that have failed by cracking them open, cleaning the glass, glueing them together every couple of years?
Once a unit has failed or lost it's vacuum seal the thermal properties are toast. It will fog forever.
Let go the nickel.....
Gabe
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I repaired the first unit (3ft by 6ft door section) 8 years ago and it is still unfogged, as are the rest. The time spent doing it was less than driving to buy a new one and installing a new unit.
*
Most thermal panes that fail and fog up is because the seal fails and sucks in moisture which fogs. You have no way of duplicating the original thermal properties therefore.....you have two panes of glass and a spacer stuck together, period.
The entire concept of thermal panes is improved thermal resistance to reduce the cost of heating and cooling. If you save money by "rolling your own", you're paying more for energy.
Let go the nickel, it's costing you a dollar.
Gabe
*Art, I'll venture a guess that the glass you couldn't clean may have had an inside coating(low-e?) which reacted with the moisture and oxygen introduced through the leak. Or maybe you live in an area with a high pollutant content in the air which chemically etched the glass.Whatever, double pane windows derive much of their R-value from the inert gas(either nitrogen or, in the better brands, argon) used to fill the cavity. Replacing this with dry air may cure your fogging problem, but you've substantially reduced the insulation advantage of the double-pane glass.You may be costing yourself in the long run.Bill
*I read an article that said you will not pay backthe cost of double pain / lowE glass for 25-50 years depending on climate . so my guess is that not spending the nickel is a nickel saved . If you want to improve the performance of your windows that you work onthe weather striping and tighten them up eliminating leaks. Mineals ,pollutants in the air /water that sits onthe surface of the glass will etch it. You can polish the surface if you hve the right equipment ,if not spend the nickel on new glass.
*
Now you all done got me wondering about the efficiency of Pella's Designer and Architect series of windows with the "removable glazing panels".
*I believe I read that older sealed glazing units were sealed with dry air between the panes and a desiccant in the seal frame. Gas filled units are much more recent than Art's units. The film could be an oxide of metals from within the glass - try vinegar. It sounds to me like a job worth doing. It works, after all, and I can't believe the insulating value of an air filled unit sealed this year would be a lot different from an air filled unit sealed 29 years ago. On the other hand, if it fails again in six months, you've got no-one to call and raise hell with.
*Andersen used a glazing called welded glass. It looked like glass bent over on itself and had about a 3/8" airspace between the glass. You can see the BB size hole in the glazing where the inert gas was installed. Most companies back then used good old ambient air with desiccant surrounding the perforated metal spacer between the glass. You can determine the mfg and age of the glass by the stamped marks on the metal spacer. Andersen's welded glass had the date acid etched in the corner of the glass.
*Scott, the Pella glazing would probably be a slightly better insulator than conventional air-filled sealed units. The insulating value of doubled glass increases until the gap between the panes is about 3/4" (like the Pella glazing) and then drops rapidly. The thing is, once the gap is greater then 3/4", there are convection currents transferring heat from one side to the other. A gap less than that will be dead air. I'm just guessing, now, and havewn't seen any stats on window performance.
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As for deaf air space, any thing over 3/4" is considered diminishing return. Anything less than 3/8" not really worth it. The Pella units are reasonably effective but not as effective as the insulated glass. Ever notice they offer it in the windows for an additional charge. It is also the standard in their pro line window.
I've toured a couple of plants (not recently) & rember the air between the panes being ambient air relying oon the desicant & glue to keep additonal air & moisture out to prevent fogging.
The pay back on low-e & gas fill was in question not the value of thermal (double pane) glazing. Low e is more a comfort & fading issue than an efficancy one.
Finally, Art where on earth did you find the ingedients you listed to make the seal for the glass? I can belive you were succesful in seperating the panes of glass from the spacer as alot of the gsealents used at that time are failing & puling away from the glass on their own ( No body offered low e glass then ). I'd bet nature gave you a big head start.Having reglazed way more windows than I would like like to belive, I have to belive you either have way too much time on your hands, need a hobby or you split the plys on the tolet paper apart & still have your first nickel. What ever the case may be, I can't for the life of me see a benifit in resealing the windows at home.
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If my memory serves me, Pella also offers insulated glass with the removable glazing panel [3 panes of glass] in their Designer and Architect series of windows. This enables the use of slim-shades although I'm not sure if there is room for slim-shades and grilles both. I have toured Andersen, Crestline and Pella plants and will probably be touring Marvin in the near future. I always use Low-E but can't justify the pay back on argon filled glazings. [I'm a spec-home builder]
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b "INSULATED GLASS FOGGING"
Of 64 units installed in a house built 29 years ago, about 14 have "fogged". By removal of one pane with a heat gun and thin knife, the interior can be cleaned, then resealed with Butyl/polyurethane/polysulfide mix and some dessicant, which is usually successful.
About 5 of these units could not be cleaned since the "fogging" was literally etched into the inside of the panes.
Does anyone have any information about what causes this etching - could it be bacterial, outgassing effects, global warming, or untraviolet b;yproducts of whatever.
*
All,
I seem to remember reading that there is some debate as to how long the inert gas of choice actually remains between the panes.
Wish I knew where I read that, as I can't offer anything more concrete.
Jerry