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Cleaning and Polishing

A clean, wet, high-gloss surface is essential to successful mirroring. Even the lightest fingerprint creates a barrier between the metal and the substrate.

Go to our silver mirror video to see how we clean flat glass.

 

 

Cleaning

Any exposed surface will have dust, grease, fingerprints on it. These must be removed for the mirror to take. The inside of an object to be mirrored also has particulates on the surface though not fingerprints. Cleaning is the process of removing these without adding back films or smears of suspended contaminants. A newly-blown glass object, on the other hand, can usually be mirrored without any special preparation.

Start by wearing rubber gloves to avoid adding your own fingerprints and to protect your hands from cleaning materials. Apply a cleaning powder or liquid and use hot water with a soft tool like a sponge or paper towel. You can use hot tap water for cleaning. The water from most hot water taps is about 140 ° F. (60 °C.) but tepid 110 ° F. (43 °C.) water can also be used. After rinsing off with more hot water your surface should be back to the way it was originally made.

Unlike many commercial glass cleaners like Windex™ or detergents like dish soap like Dawn™, our laboratory-grade cleaners rinse clean without leaving a residue. Bon Ami cleaner, while useful for leaf gilding, does not leave the surface clean enough for chemical mirroring.

If you have just stripped the paint from the back of an existing mirror ready for antiquing or re-mirroring, you may need to removed the residue from the paint stripper with acetone before cleaning it with glass cleaner.

Mirror Removers

We have a number of products that are designed to remove existing mirrors or stains from surfaces in preparation for mirroring. Used selectively (for example with masking) you can use them to decorate or antique a mirrored surface. (see Compare Mirror Removers.)

Polishing

Polishing with an abrasive can help to remover really stubborn dirt on any type of glass. Most plastics are too soft to polish and abrasives can ruin the glass-like surface. We recommend using new plastic for mirrors, if possible.

Each abrasive has its own characteristics. Sprinkle a small amount on the surface and add hot water to make a slurry. Use a pure wool felt polisher to scrub the surface. Synthetic polishing material can scratch the glass. Use a clean sponge or brush to physically remove the used compound and finish with a spray of distilled water.

  • Cerium oxide - a mixture of several very similar chemical compounds but the main one is ceric oxide. It polishes glass by abrasion and by a chemical reaction with the glass.
  • Whiting - an inert white powder often used to polish the face of a mirror
  • Aluminum oxide - more aggressive than cerium oxide and very useful for refreshing old glass or adding "tooth" to new glass by simple abrasion
  • Pumice - an aggressive abrasive that is very useful for removing backing paint

Wetting

The last thing before starting the mirroring chemistry is to make sure the surface is "wet". By this we mean that a flow of water runs off the surface in sheets rather than spots or drops. A simple visual check ensures that the chemicals will actually bond to the surface and not be repelled by areas of low electrical conductivity.

While the cleaning compound will often have taken care of this requirement, some materials such as plastics are notoriously difficult to wet. We have provided a Wetting Agent Wetting Agent (a kind of surfactant which breaks the surface tension) which can be applied to such substrates before pouring or spraying on the chemical sensitizer.

Water Etch

One particular problem with glass surfaces that have been left partly-covered with water is called water-etch. The water has actually etched into the glass and it may be difficult or impossible to polish away the imperfections without mechanical grinders or polishers. It is often easier to replace the glass than try to fix this.

Cleaning Tools

Soft paper towel is commonly used for the initial dirt removal and the final dry polish of the front surface. A sponge gives you a more definite way to apply cleaning materials. A felt block or our maple felt polisher is particularly efficient at polishing. While motor-driven polishers can be used, you must be careful not to burn swirls or circles into the glass. We have cleaning mats available to support glass without breaking and to protect your work area from liquids and chemicals.

Beveling

This is the grinding technique used to product an angled edge on glass. It should always be done using water as the lubricant as oil tends to absorb into the glass and can be very difficult to remove, making wetting and therefore mirroring difficult or impossible.

Antiquing

While a surface that is to receive an antiqued mirror is less demanding of polishing requirements, you will no doubt want the antiquing to occur where you intend it rather than showing the effects of bad cleaning. Making an antique mirror from clean glass will give you better control of the process.

Troubleshooting

A sure sign of inadequate surface preparation is an uneven mirror. This will often show up as thin mirroring on the edges where most handling has been done. Incomplete removal of cleaning compounds such as cerium oxide can also lead to unsatisfactory results. If in doubt, make sure that the water sheets from the surface and does not bead up, especially at the edges.