At some point, you might notice black spots on your bathroom mirror, especially on the edges. You tried whipping it with a towel or washing it with water but they refuse to go away. These are the mirror rots caused by various external factors. These black spots can cause noticeable flaws on your bathroom mirrors. So continue reading this article, as we will be talking about the causes of the unwanted black spots and preventive measures to make sure your bathroom mirror stays free of black spots and maintain its beauty.

What causes those black spots to appear in bathroom mirrors?

Whether you ordered a mirror from an online store or you picked up a mirror from a store near you, black spots on mirrors are bound to occur due to de-silvering or mirror rot. The component responsible for transforming a plain glass to a mirror is silver nitrate. The silver nitrate is then safeguarded from damage with copper-sulfate protection coating.

Paint sealants are also used to provide extra protection for the mirror’s back. When these coatings are exposed to external elements such as moisture and air, dark spots appear. This happens due to the oxidation of the copper sulfate and silver nitrate caused by condensed moisture from splashes of water and other elements like exposure to air.

Let’s look into the individual causes of these black spots.


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Moisture is the chief cause of black spots on bathroom mirrors; make sure that you remove every moisture on the surface and behind the mirror before installing it. During the shipping of the mirror, temperature change may occur and condensation will develop leading to the mirror become moist. Dry the moisture with a towel and air-dry for a while before you install it. Overtime, take necessary precautions to prevent water from touching the mirror – avoid hanging your bathroom mirrors in high humid areas such as near a steam pipe or a water source.


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The occurrence of black spots on bathroom mirrors these days is not as frequent as before; this is due to an improvement in mirror coatings. When installing the mirror, hand gloves are used to protect the hand – the chemical residues and body salt on the hands can cause damages to the backing, thus leading to black spots. Clean with warm water and lint-free cloth – you can also clean these unwanted chemicals with window cleaners but avoid allowing moisture to stay on the surface for long. You can achieve this by spraying the window cleaner on a towel before using it on the mirror instead of spraying directly on the mirror.

Note: Avoid using cleaners with a heavy ammonium base as this may damage the backing and mirror edges.


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Allowing adequate ventilation space for your bathroom mirror is also a good way to prevent black spots. You can do this by leaving enough room between the mirror and the wall to allow air passage to the back of the mirror and help dry unwanted moisture on time. For those in coastal regions, it is particularly important to have proper ventilation for your bathroom mirrors because of your wet weather conditions.


DIY solutions to those black spots

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While the spots are repairable, resilvering may require professional help because of the harmful chemicals involved, it can also be expensive. However, you may not need to go through the stress of resilvering as there are eco-friendly preventive measures you can deploy to make sure these black spots never happen in the first place.

  • Use a custom frame

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Maybe you preferred a frameless mirror to give your bathroom a certain look, which is ok – but if you want to prevent these black spots from ruining the aesthetics of your mirror, you’d have to get a framed mirror or you can add frames yourself to your frameless mirror.

Adding this frame will help prevent the mirror edges from being exposed to moisture and air thereby preventing mirror rot.

  • Tape some desiccant to the back

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Desiccants come with some shoes and even some food packages, if you have any at home; tape one to the back of your mirror to help absorb excess moisture. If your mirror is quite big, you can use as many desiccants needed to cover the whole mirror-back to prevent moisture build-up and causing black spots.

 Recommended precautions to avoid black spots to appear on bathroom mirrors

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This may not be a 100 percent guaranteed solution to prevent black spots on your mirror, but it does help. All you need to do here is to be careful when having your bath, washing your hands, or brushing your teeth when you’re close to the mirror. Try as much as you can to restrict water spillage on the mirror and dry the mirror immediately when you splash water on it – especially near the edges.

It is possible for these black spots to occur even when you have taken all the preventive measures. Fortunately, they can be repaired. You can stick pieces of aluminum foil behind the mirror where the coatings have peeled off, or you can use a silver color spray paint on those areas.

However, if you are dealing with excessive damage to your mirror, calling a professional is the best option. Resilvering the mirror involves a lot of harmful chemicals so it’s better for you to let a professional handle these things. Calling a professional might be expensive but it is always better than taking the DIY route and risking your health in the process.

Final thoughts

Completely eradicating the possibility of black spots may not be feasible but you can give your mirror a very long shelf life by following the above preventive measures. Sometimes, getting a new mirror may be the only option you have, do not put your health on the line by trying to use harmful chemicals in the name of resilvering your mirror.

There are other less harmful methods like using silver pants to paint the back of your mirror or you can use pieces of aluminum foil to cover the affected areas.

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