Dark marks around a bathroom mirror are commonly described as the mirror “turning black.” The glass itself hasn’t changed colour. What you are seeing is damage to the reflective silvered coating on the back of the glass.
This damage is called mirror desilvering or delamination.
Can black edges on a mirror be repaired?
Unfortunately, no. Once the reflective coating has deteriorated, it cannot be repaired. The mirror needs to be replaced.
Understanding the cause can help you choose a better replacement and reduce the chance of it happening again.
What causes mirror edges to deteriorate?
Bathroom mirrors are exposed to much more than steam. Moisture, damp dust, cleaning products and poor-quality materials or installation can all contribute.
Steam, condensation and coastal air
Bathrooms naturally produce moisture, particularly when ventilation is poor—or when there are teenagers in the house who looove a long, hot shower.
Many of our customers live close to the ocean on Sydney’s Northern Beaches, where moisture and salt are already present in the air. Repeated exposure can affect a mirror’s vulnerable edges and backing.
Damp dust along the top edge
Dust collects along the top of an unframed mirror and becomes damp from steam and condensation. It can then hold moisture against the edge, allowing it to gradually seep towards the reflective backing.
Regularly wiping the top edge is a small job that may help protect the mirror.
Cleaning products containing ammonia
Some glass cleaners contain ammonia or other harsh chemicals. Problems can occur if the product runs down the mirror and reaches its edges or backing.
Apply cleaning product to a cloth rather than spraying it directly onto the mirror. This helps prevent excess cleaner from running behind it.
Water collecting along the bottom edge
A mirror sitting directly on a vanity benchtop can be particularly vulnerable. Water from washing hands, splashes from the basin and benchtop cleaning products can collect against the bottom edge and seep or wick into the backing.
Poor-quality materials or installation
Some inexpensive imported mirrors bought online may have unprotected edges or MDF backing. MDF readily absorbs moisture and can hold it against the mirror.
Not every imported mirror will fail, but it is important to know how it has been made and whether it is suitable for a bathroom.
Should bathroom mirror edges be sealed?
Traditionally, many glaziers leave the edges exposed so that moisture behind the mirror can evaporate. If silicone is applied but even a microscopic pinprick is left, moisture may still enter and then have nowhere to escape.
Professionally sealing the edges can provide protection, but it must be done correctly. Only pH-neutral, mirror-safe silicone should ever be used. Standard silicone and unsuitable adhesives can react with and permanently damage the reflective backing.
An experienced glass installer should consider the room’s ventilation, moisture levels, proximity to the ocean and mirror position before deciding how its edges and backing should be protected.
When is a framed mirror a better choice?
Bathrooms contain many hard surfaces—glass, tiles, stone, mirrors and metal tapware. An unframed mirror can sometimes add to a clinical or hospital-like feeling.
The right frame softens the room and makes it feel warmer and friendlier. In a bathroom, it can tie in with the tapware or bring out the natural tones of a timber vanity. In a bedroom or living room, the frame can connect the mirror with the furniture, artwork and other finishes.
A frame also has a practical benefit. When we make a custom-framed mirror, we can correctly seal it into the frame, protect its vulnerable edges and use an appropriate product on the back.
This can be particularly helpful in busy family bathrooms, coastal homes and rooms where the mirror is close to a vanity or basin.
What should you ask when ordering a replacement bathroom mirror?
Before accepting a quote, ask:
- Is the mirror suitable for a humid bathroom?
- What quality of mirror glass will be used?
- How will the edges and backing be protected?
- Will only pH-neutral, mirror-safe silicone be used?
- Will the mirror sit directly on the vanity benchtop?
- Would a framed mirror be more suitable?
- Has the installer considered the room’s ventilation and moisture levels?
- Is the installer experienced in professionally sealing mirror edges?
The cheapest mirror may not be the least expensive option if it begins deteriorating again after a short time.
At Artform Collective, we custom-make and install framed and unframed mirrors for bathrooms, bedrooms and living rooms throughout Mona Vale and Sydney’s Northern Beaches. We consider the room, wall, position and moisture exposure before recommending the most suitable option.
If your bathroom mirror has started to deteriorate—or you need a new mirror for another area of your home—email us or visit our Mona Vale showroom. We can help you choose a mirror that looks right and is properly suited to the space.