Glass Cutters Are for Tools: How to Dissolve Glass Using Sodium Hydroxide

Glass is one of the least reactive substances known to chemistry. It is the standard container material for almost all lab chemicals because it's so inert. But there are a couple of substances that have strong reactions with glass. Sodium hydroxide, aka solid drain cleaner or lye, can easily be stored in glass as a solid, but when molten, it reacts violently with glass and can actually dissolve it away! So, the next time you clog up your drains with broken glass beakers and flasks, rest assured your household drain cleaner has what it takes.

Materials

• Sodium hydroxide (lye)
• Steel container
• Propane torch
• Glass bottle
• Pliers
• Safety goggles
• Heavy protective clothing
• Respiratory protection
• Thick gloves

Find a Suitable Glass

Some glass is thicker than others. For the most dramatic results, try to pick a thin-walled glass bottle or jar. Be sure that all labels are removed from the area you want to dissolve. This will give the sodium hydroxide more surface area over which it can react.

Set Up Dissolving Chamber

While the molten sodium hydroxide will dissolve glass, it will not react with steel. Just about any soup can or cat food tin will work as a dissolving chamber. Aluminum will not work, as it would dissolve. Test the metal container with a magnet to be sure it is magnetic and therefore steel.

Set your steel container on top of something nonflammable to expose the bottom to the propane flame. I used these old paint cans to hold up my chamber.

Prepare Ingredients

Pour a tiny amount of lye inside so that it covers the bottom of the can. Next, fill the bottom of the jar with lye.

Heat and Dissolve

Place the jar inside the can and begin heating the bottom with the propane torch. The reaction can take a few minutes and may require that you add more sodium hydroxide as you go.

Above, the lower lye has melted and the lye inside the bottle as begun to liquify. Below, all molten!

Now we wait for the glass to dissolve.

Warning

• This project is for display purposes only. Do not attempt this project at home. I am not responsible for any injury or death that comes as a result of repeating this project at home.
• The fumes produced can be harmful, so be sure you do this in a fume hood or outside with proper respiratory protection.
• Molten sodium hydroxide is extremely corrosive to human flesh. Cover all parts of your body and face while heating the can.

The liquid lye eats away at both the inside and the outside of the glass. The sodium hydroxide and the silicone dioxide in the glass react to form sodium silicate. In heated liquid mixture, this new sodium silicate dissolves away leaving only a hole in the glass.

Hypothetically, if you have a steel print with channels for the sodium hydroxide to flow into, you could do intricate glass etchings this way.

What would you do with the power to dissolve glass? Let us know in the forum or post your own video to the community corkboard.