सीरियम ऑक्साइड (Cerium oxide)

Cerium oxide, also called ceric oxide or cerium(IV) oxide, is a fine pale yellow to off-white powder made from the rare earth metal cerium. Glass workers use it as a polishing compound because it smooths glass faster and cleaner than most other powders.

• Formula: CeO2
• CAS number: 1306-38-3
• Molar mass: 172.12 g/mol
• Melting point: about 2,400 °C
• In water: insoluble, so it stays as a suspension rather than a solution

The polishing works partly by gentle abrasion and partly by a chemical reaction at the glass surface. That is why it gives a clear finish instead of the dull scuffing you get from sand or scouring powder.

Azlok sells cerium oxide as a general polishing powder for glass and similar hard surfaces. Every pack comes with a 4-inch (about 10 cm) felt polishing disc, often called a namada disc, so you can start work with a drill straight away.

These are technical grade polishing powders, not lab reagents. For current rates, check today's price per kg.

Household and DIY

• Removing light scratches, hard-water spots and haze from mirrors, windows and shower glass
• Polishing glass tabletops and display cabinet glass
• Restoring cloudy car windscreens and removing wiper marks

Trade and industry

• Final polishing of optical lenses, spectacle glass and precision glass
• Polishing flat glass, gemstones and some stone surfaces
• Used as a catalyst material and in glass making to control colour

It will not fix scratches deep enough to catch your fingernail. Those need grinding first, which is a job for a glass shop.

1. Clean the glass well with water and dry it. Grit left on the surface will scratch it further.
2. Mask nearby rubber seals, paint and plastic trim with tape.
3. Mix the powder with water to a thin, creamy slurry. Roughly 1 part powder to 2 parts water by volume is a good start; add water if it feels pasty.
4. Fit the felt disc to a drill. Dip the pad in the slurry or spread some on the glass.
5. Work a small area, around 30 cm by 30 cm, at low to medium speed. Keep the pad moving and flat, with light, even pressure.
6. Keep the surface wet. Spray a little water if the slurry starts drying.
7. Every minute or so, touch the glass with the back of your hand. If it feels hot, stop and let it cool. Overheated glass can crack, especially toughened or cold glass.
8. Wipe off, rinse with clean water and check against light. Repeat on stubborn spots.

A light scratch on a mirror usually takes 5 to 15 minutes of work. Clean the felt disc in water after use and let it dry.

• Wear safety glasses. The drill throws slurry, and you don't want it in your eyes.
• Avoid breathing the dry powder. Open the pack gently and mix it with water away from your face; a dust mask helps if you handle large amounts.
• Use gloves if you have sensitive skin, and wash hands after work.
• Keep the drill cable and socket away from water.
• Store in a sealed, dry container. The powder can pick up moisture and form lumps, though it still works once broken up.
• Keep away from children and pets.
• Wipe up spills with a damp cloth rather than sweeping, so dust doesn't fly. Small amounts of used slurry can be wiped up and thrown away with solid waste; don't pour large quantities down the drain.

If you only have one or two marks on a mirror or a single scratch on a window, the 100 g pack is enough. For a full car windscreen, a few windows or a bathroom of glass, go for 250 g. The 500 g pack is the sensible pick for detailers and glass shops who polish every week.

All three packs come with the same 4-inch felt disc. If you plan heavy work, keep a spare disc, because a worn or clogged pad polishes slowly and heats the glass more. For workshops buying 25 kg or more, send a bulk inquiry and we'll quote on larger packing.