How to repair mirror desilvering (those horrid brown edges)
Step-by-step tutorial on how to remove rust and reduce the effects of unsightly desilvering aka mirror rot or oxidation.
How did I discover this mirror desilvering fix? Back in 2021, I was sponsored by WD-40 to create some TikToks from my bathroom to help increase awareness about their Fix it Challenge. The tiktoks demonstrated unusual, DIY-related uses for WD-40, and I thought you might find the ones I came up with helpful, so I’m popping them up as super quick blog posts. For complete transparency, I have not been asked to do this by WD-40 and will not receive anything for doing so. There are also lots of hacks, tips and tricks over on my Instagram.
What is Mirror desilvering?
Desilvering is basically water damage and refers to that annoying process when the backing of an old mirror deteriorates and you get dark spots that turn to black edges. It is also known as mirror rot, water damage, oxidation or tarnishing. It is often seen in bathroom mirrors because of the high moisture levels (from baths and hot showers) in the air, which penetrate the mirror edge and can also occur where moisture drips down the mirror and onto the bottom edge, causing rust to form. This effect can look attractive on an antique mirror, but this minor damage is not what you want on modern mirrors. If you have this issue in other rooms due to excess moisture in the air, you might also like to read my posts about managing condensation in your home and how to use a dehumidifier to tackle condensation.
The best treatment for this common problem is actually prevention (more on that in a minute) as to ‘resilver’ the edges of a mirror you need specific chemicals and is really best left to the professionals. There are ways you can hide the damage such as by painting or taping a frame onto the mirror, or in fact by adding an actual frame, but after much research on the internet I couldn’t find any great ideas for actually removing the unsightly rust to make the damage less noticeable. As we have a mirror with this issue in our bathroom I set about testing an idea I’d had after seeing lots of rust removal hacks using WD-40.
What you’ll need to treat a desilvered mirror
Old toothbrush
Cleaning sponge
How to repair mirror desilvering
- Point the straw under the mirror, getting as close to the gap in the join between the front and backing of the mirror (where the moisture has penetrated) as possible and spray the WD-40 whilst moving the can along the base of the mirror.
- Leave the WD-40 to do its thing for 10 minutes or so.
- Take an old toothbrush and place it under the mirror so the bristles are on the line of the join.
- Angle the toothbrush so at least some of the bristles get into the gap and scrub backwards and forwards. You should be able to see the bristles moving the rust particles if you look through the mirror.
- Give the underside of the mirror another spray with the WD-40 and repeat the scrubbing until all the rust has been removed.
- Once complete mop up any WD40 from the mirror, tiles and sink area.
- Be sure to throw away the old toothbrush or put it somewhere where it can’t be used accidentally!
As you can see from the above photos, after completing this simple solution my bathroom mirror’s reflective backing is obviously not back to its original condition but the good news is it looks so much better than it did with the rust and from a distance you can’t actually see the damage. It’s a good idea because the WD-40 will also help prevent the rust coming back and the desilvering getting any worse which leads me on to preventing it in the first place…
I have seen mirror repair tape advertised as the solution to a desilvering mirror which is reflective and designed to make the mirror look undamaged to give it a new life, but I didn’t think the level of damage to my mirror warranted this. Let me know if you’ve tried this tape before and have any feedback, is it the best solution?
How to prevent mirror desilvering
Like many home maintenance tasks, the key to preventing the common issue of mirror desilvering or oxidation is to stop any moisture / water vapour being able to penetrate the edge of the mirror. For best results apply a layer of sealant to the mirror edge. WD-40 can be sprayed on the mirror edge regularly in its capacity as a water repellant and this will help prevent the formation of rust and those unsightly dark streaks. I’ve written a whole post about 5 clever ways to prevent mirror desilvering which you might like to read.
If you are looking for a permanent DIY fix to cover the affected mirror edge, read my post about bobbin mirrors and how to make a DIY bobbin frame for your oxidised mirror.
In summary, mirror desilvering occurs when the reflective silver coating on the back of the mirror deteriorates, leading to black spots or discoloration along the edges of your mirror. This is especially common in older mirrors, like a family heirloom or a mirrored medicine cabinet you might find at a flea market. Over time, exposure to harsh chemicals or air moisture can cause damage to the silver backing on the back of the glass, leading to a loss of the mirror’s reflective quality. The best way to address this issue is through the resilvering process, where a silver nitrate solution is reapplied to the mirror’s glass surface. However, if the mirror is badly damaged, a mirror replacement might be a good option, especially for residential mirrors with no sentimental value. For valuable or high-quality mirrors, such as those with beveled edges or a custom mirror with a new frame, using resilvering services can restore the mirror’s appearance. If you fancy trying a DIY repair job, then have a go at my WD40 method, but be prepared that while you won’t be able to completely restore your mirror to its former glory, you will be hopefully be able to get it looking hugely improved.
Where next?
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Pop over and see behind-the-scenes of my projects over on Instagram.
