Academic journal article
By Roy, Ken
Science Scope , Vol. 32, No. 9
What do overflow cans, catch buckets, ring stands, electroscopes, magnets, balances, and microscopes have in common? All of these items are commonly found in middle school science laboratories. But more importantly, they usually are made of metal, and metal tends to corrode.
Corrosion is a broad term that applies when something is being broken down due to a chemical reaction. Rust or wet corrosion is a specific type of corrosion where iron or steel reacts with water. Science teachers often find that over time, laboratory equipment made of metal may tend to look dull and have symptoms of corrosion. In fact, in certain instances, such equipment may become unsafe to use and provide bogus data results on student experiments.
There are several strategies that can be used to address corrosion of lab equipment. Consider the following suggested approaches:
* Know the behaviors, characteristics, and properties of assorted metals and alloys before you purchase any metal equipment for the lab. Specifically, know how to recognize corrosion and understand how metals interact with corrosives.
* Clean metals and metal surfaces using appropriate methods and materials, such as intensive washing and drying, polishes, rust converters, and other preparations.
* Isolate and stabilize metal surfaces by applying protective coatings (paint, lacquer, plastic) to prevent contact with oxygen in the air. Temporary coatings such as polish or wax can be used, but must be periodically replaced.
Rust never sleeps
Many types of metallic lab equipment contain iron or steel, including ring stands and magnets. Over time and under the right conditions, low-temperature oxidation in the presence of water or iron can occur, producing a characteristic coating of powdery or scaly reddish-brown or reddish-yellow hydrated ferric oxides. The most practical method for preventing rust is to keep your iron or steel away from oxygen or moisture. Suggested strategies to reduce exposure to humidity/water to reduce or prevent rust on metallic lab equipment include the following:
* Paint the surface or apply a rust-preventative coating. Waterproof emulsion can be painted over metal surface so that moisture, water, and oxygen cannot access it. A coat of clear nail polish or lacquer can be put on some metal items to help them stay corrosion free. A light coating of wax can also be used to keep metal equipment from corroding. Caution, however, must be taken in making sure equipment subjected to heat, such as burners, is not coated with potentially flammable materials.
* Provide climate control in the storage area. Use of a dehumidifier can help to reduce humidity in the storeroom.
* Another effective alternative to an expensive dehumidifier and its costly operation are rechargeable silica gel desiccants. To reduce moisture and humidity exposure, silica gel desiccants can be placed inside the plastic that covers the equipment. The waterproof or rustproof wrapping (such as plastic) will extend the life of the equipment by reducing exposure to corrosion factors. …