Why Does Glass Change Color Over Time? Springfield Glass Answers

Have you seen some old glass windows up close? You might see black streaks, brown spots, or even rainbow-colored wavy streaks within the glass. What causes this discoloration? Springfield Glass Company explains in today’s blog.

Related Post: Springfield Glass Company Discusses the History of Glass


Moisture is the most common cause of window discoloration, particularly for double-pane windows. Lingering moisture can become trapped within the panes (usually due to shoddy workmanship before installation). Moisture then allows mold and mildew to thrive. The usual colors are black or brown, but you might see orange, green, or white streaks depending on the type of mold. We’ve seen all kinds of discoloration with repair or installation projects completed by Springfield Glass Company.

Old Age

Some glass windows are simply old. Due to antiquated manufacturing techniques, you might see wavy streaks of rainbow colors that start from the top of the window and work their way down.

Another interesting aspect of this phenomenon is that some types of antique glass are very slightly liquid. They feel solid. But the internal structure of some antique glass maintains a slightly liquid form, which is why the rainbow streaks look wavy and gravitate downward. Of course, this very slight liquidity is hardly noticeable as it takes several decades for these rainbow streaks to form.


There are three ways to solve discoloration on windows. 

Cleaning. Some discoloration may go away when you clean the window, but that’s only discoloration on the outside of the pane. Internal discoloration requires a different remedy.

Tinted film. Tinted film turns your window a different color, and it’s good for improved thermal control of your building. However, tinted film only masks the true problem of moisture or old age.

Window replacement. The only way to truly solve internal discoloration of windows is through replacement. Springfield Glass Company can replace your old windows with new ones that are modern and will last a lifetime.

Related Post: Our Residential Glass Installer Talks About the World’s Most Famous Glassmakers 

New Glass Installation by Springfield Glass Company 

The team at Springfield Glass Company can install new residential and commercial glass for any situation. Contact Springfield Glass Company online or call (417) 883-6555 for more details.

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