In my bathroom I have a beautiful illuminated LED mirror. It's now 10 years since I originally installed it - and over time, the edges have become de-silvered as the backing coat has corroded and peeled away.

Research into mirror re-silvering tells me that it's not worth it. Besides, some of the corrosion has extended beyond the edges and into the internal workings of the mirror: meaning it's not possible to access the backing coat in those places.

I have been lucky enough to find a replacement mirror from surplus stock: they don't make many of them any more, and I needed the exact model in order to match the mounting points in my tiles.

Before I mount the new mirror, however, I want to do everything possible to prevent the new one becoming similarly corroded. Research informs me that mirror edges corrode in high-moisture environments (like bathrooms) when water condenses on the backing surface and loosens it. I have no option to affix a physical frame around the mirror: its design does not permit that. Therefore I'm looking for some kind of sealant which I could apply to the exposed parts of the backing, in order to protect it from corrosion.

Given how common this problem is with bathroom mirrors, I would have thought that there would be lots of products on the market to do this. However I have only found one single product which is explicitly marketed to protect mirrors from moisture corrosion. This is only sold in Australia, and I'm disinclined to pay the exorbitant postage costs to send it to me in the UK (which are more than the product costs in the first place!)

So - I'm looking for generic suggestions for how to seal my mirror's edges to protect it for many years to come, so it doesn't corrode.

3 Answers 3


Try using clear nail varnish on the edges and/or where the mirror is attached to the backing, usually formica covered wood or plastic.I work with stained glass and have always used it with good results.Obviously use a quality product, not a cheap version. This is usually where the de-silvering starts due to moisture creeping in.The rest of the mirror backing ( if accessible,would probably appreciate a varnish spray coating.


I would use a clear varnish. Varnish has very little body and would seal the edge where the glass and metalized layer are exposed. By sealing this edge moisture can not get in and start delaminating the new mirror. If you want something with more body use a silicone sealer. Both should work well to prevent your new mirror from having issues with the moisture.

  • Thanks. Do you have any actual experience doing this (i.e to confirm the results)? Commented Dec 31, 2019 at 8:37
  • 2
    Yes we used clear varnish to protect antique mirrors, the first step on ones that have started to delaminate is to bake them out to remove the moisture, then apply a coat of clear varnish. Some mirrors the entire back needed to be sealed as some minor pitting had started in the visible field, sealing stopped the damage from getting worse. If the mirror is two large to bake it out , we used isopropyl alcohol saturated and wiped clean several times then used a hair dryer and sealed this worked well for a huge bar mirror.
    – Ed Beal
    Commented Dec 31, 2019 at 16:41

We put mirrors in a bathroom years ago and varnished the edges and back of each mirror with 2 good coats of varnish.

They eventually failed - time and the temperature / humidity cycles take their toll.

If you can get a replacement mirror now then get two and keep one for the future.

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