A: John Weaver, who handles customer service inquiries for Circle Glass and Mirror in Fairfax (703-273-2700; circleglassandmirror.com), looked at the images you submitted and found that the haze was definitely condensation, the units form in double glass panes as soon as the desiccant in the spacer between the panes is saturated. Double pane units are made with a thick sealant on the edges, but the seal is never perfect. Over time, warm air, which holds more moisture, seeps into the gap between the pieces of glass and releases that moisture as it cools. The desiccant absorbs it and keeps the glass clear – until the desiccant no longer works. At this point, the only remedy is to replace the glass units.
The etch or scratch marks you see are caused by the failure of a low-E coating that was applied to the glass, Weaver said. Low-e, for “low emissivity,” means a microscopic coating of metal particles that reflect some wavelengths of light while transmitting most of the visible wavelengths. Low-E coatings keep most of the ultraviolet wavelengths out, which prevents furniture from fading. Depending on the coating and the glass surface it is applied to, Low-E coatings can also reflect infrared wavelengths outwards or inwards, which can help keep homes warmer in winter or reduce the load on air conditioning systems in summer.
Low-E coatings can be “hard coatings”, which means that they were sprayed onto the molten glass when it was formed into sheets, or “soft coatings” that were later applied in a vacuum chamber. The hardcoat process allows the glass to be cut and tempered, and it forms a strong enough bond that window fabricators can add features such as blinds between the panes. The soft coat process is more fragile, but leads to better energy savings.
“Some of the older low-e coatings have struggled to adhere to the glass for more than five to seven years,” Weaver said in an email. “It’s a totally organic failure, and it’s not atypical of soft-coat low-E’s. If you’ve ever had sunglasses with the coating peeling off, it’s exactly the same thing. “As you have noticed, the coating cannot be cleaned or even scraped off because it is between the two panes of glass inside the device.
To see clearly out of your windows, you don’t need to replace the entire window set, just replace the glass units that look cloudy. Cloudiness is a visual problem. This has no significant impact on energy efficiency. If the cost of replacing is too high for your budget, you can delay until your finances are in better shape.
You would have to contact glass companies – not window replacement companies – for quotes in your area. In the Washington area, replacement double pane units from Circle Glass typically cost between $ 75 and $ 125 for materials (depending on size, coating, and mesh) and $ 25 to $ 50 for labor if a homeowner brings in the framed wing for Measurements and returns about 10 days later to have the new units installed, Weaver said. The company can also take two trips to a house, once to measure and again to install. Working with this option starts at $ 235 for one window plus $ 50 to $ 75 for each additional window.
If you decide to swap out the glass in your kitchen windows, choosing low-e glass still makes sense in terms of energy efficiency and convenience. However, Weaver cautioned that the newer coatings could change the color of the glass, which could change the tones you see when you look out. He said it was almost impossible to match the color of new low-e glass with older low-e glass on the shady side of the house, where keeping the heat out of sunlight in the summer is less important.
Weaver said based on what he was told, “the newer low-e coatings are much more durable and more securely bonded to the glass than the older generation low-e coatings.” He said the sealant on the glass should last five to ten years, and the coatings should last several years.
For new windows, manufacturers offer guarantees against tarnishing and other defects that extend over many years. So it may be worth digging up the records for your windows if you still have them. For example, Milgard offers a lifetime guarantee as long as the buyer lives in a home. It also covers 10 years from the date of installation if the house sells. However, integrated into the warranty calculation is the total cost of the windows, which is much higher than just the glass units, and a gamble that most people don’t stay in the same house for a lifetime. If replacement glass units are warranted, they are unlikely to last more than 10 years.