How To Repair Mirror Silver

Re-Silvering Old Mirrors

A mirror, in its most basic form, is a piece of glass coated with silver and protected with backing paint. The silver coating is not paint - it is a very thin layer of pure elemental silver that forms directly on the glass as the silver chemicals react with each other.

This video shows you how to re-silver a beveled bathroom mirror using our Mini Silver Kit.The photo on the right is an old engraved mirror that has been re-silvered using this process.

To silver and re-silver telescopes, sextants and other scientific mirrors see our page on scientific instruments.

When to re-silver an old mirror

If the glass is beveled, curved, beautifully engraved (as in this photo), carefully shaped or has sentimental value it is certainly worth re-silvering.

Mirroring (re-silvering) is a very wet process. In order to re-silver a mirror, you will have to remove it from its frame. This is a good time to see if the frame itself needs to be strengthened or repaired. The best time to do this is after you have carefully removed the mirror.

Re-silvering a mirror does not affect the glass itself. It will not fix any scratches, chips or cracks. In fact, the bright new silver could make these defects more noticeable. If your mirror is scratched, look carefully to see if the scratch is in the glass or the silver. It is not possible to polish a scratch out of the glass by hand but re-silvering will remove a scratch in the silver layer.

Re-silvering one small section of a mirror

Before you decide to re-silver just one section of an old mirror, check to see if the backing paint is strong, smooth and firmly attached to the glass. Pouring or spraying silvering chemicals onto fragile backing paint will probably lift it off and make the problem worse.

Even if the backing paint is in excellent condition, and you are able to remove just enough of it to silver one section of the mirror, there will be a fine gray line between the old silver and the new silver. Only you can decide it this is a problem. Of course, if you try this and decide that the result was not what you want, you can always strip the entire mirror and re-silver it. Silvering does not change the glass – you can re-silver a piece as many times as you like if you remove all of the old paint and silver first.

For this process you will need a Mini Silver Kit and extra fine pumice. Polish the affected area with a paste of distilled water and pumice to smooth the edges of the surrounding backing paint and silver. Follow our Mini Silver Kit Instructions to clean, tin and silver the scratch. You can always add a second layer of silver if you think the first layer is not thick enough. Once the silver is dry, protect it with the paint in the Mini Silver Kit.

Mirror scratch repair paint

The paint that is sold to repair scratches in mirrors is made of extremely small flakes of aluminum. If you paint it on the mirror and view it from one angle, it looks perfect. If you view it from another angle it looks like a bright white line. The flakes of aluminum do not reflect light in the same way that individual silver crystals do when the crystals have formed on the glass during the silver mirroring process.

An alternative to re-silvering

The alternative to re-silvering your old glass is to remove all of the silver and paint and then buy a new mirror cut to size and place it behind the old glass in the same frame. The old glass and the new mirror must be perfectly clean before you put them together.

This trick does not work if

The frame is not strong enough to support the extra weight and thickness of the additional glass.
The glass has a design engraved into it. The back of the design will be reflected by the mirror behind it.
The trick does work if your mirror only has beveled edges because the back of the bevel is flat and it will not create a double reflection.

Tips on cleaning an old mirror

Never use a dust cloth or vacuum to remove the dust from the back of an old mirror. Leave it dusty. The integrity of the silver depends on the integrity of the backing paint. Suction and friction can loosen the backing paint and expose the silver to further corrosion.
Clean the mirror face by spraying glass cleaner on an old towel or T-shirt and then wiping the glass. Water is the enemy of mirrors. Do not spray the cleaner directly on the glass.
See more about how best to care for antique furniture including mirrors here: Porch.com

Mercury mirrors

The process of creating a mirror with silver was invented by Baron Justus von Liebig in 1835. Before that, mirrors were made with mercury and tin. Louis XIV's Hall of Mirrors at Versailles in Paris are mercury mirrors. If the back of your old mirror is covered with fine white dust and it has no paint, it may be a mercury mirror but they are extremely rare. Given that mercury is poisonous and should only be handled with gloves, they do not have a high monetary value.

We welcome any questions you may have regarding re-silvering an old mirror. Contact Us