Glass Test Tubes

Glass test tubes are pretty close to being ubiquitous in a laboratory setting. Usually roughly finger length, these mad scientist staples can be found by the hundreds in situations ranging from chemistry labs to hospitals to a kid’s chemistry set. Any place where it’s necessary to keep samples separate, you’re going to find glass test tubes.

Glass test tubes are also known as beakers, sample tubes and culture tubes, although some people maintain that there is a difference between a culture tube and glass test tubes in the shape of the mouth. Test tubes normally have a rounded lip on them that makes them easier to pour, and this may not be found in culture tubes, although the terms are generally interchangeable.

They tend to be between 10 to 20 mm and between 50 to 200mm, and may have either a flat or rounded bottom. The rounded bottom is more typical, since it discourages people from just setting the test tubes down, which can lead to breakage and accidents. As the name might suggest, most glass test tubes are made of, well, glass, but plastic test tubes aren’t uncommon. One thing that you may need to check on if you’re planning to purchase test tubes is whether the glass is regular glass or borosilicate glass.

Borosilicate glass enables you to use the glass test tubes directly over an open flame. If you try this with regular glass test tubes that aren’t design to withstand heat, you’ve got a better than average chance of the test tubes cracking or even exploding if you get them past a certain fairly low heat threshold.

Glass test tubes are most commonly used by chemists, although they are common through out most science industries. Chemists typically use them for a variety of purposes, including but by no means limited to: holding, mixing and heating liquid or solid chemicals, usually in small amounts.

Most commonly, they are used in qualitative or essaying experiments. Their shape is ideal for minimizing mass loss when pouring, and their narrow shapes helps scientists more easily control the amounts that they are pouring out of the tubes. This shape also slows down the release of gases into the environment, since only a small amount of the surface area of whatever you put in glass test tubes is going to be exposed to the environment.

It’s also fairly easy to use glass test tubes to help capture gases during experiments, particularly electrolysis experiments. Generally speaking this is done by filling the beaker up with water and then up ending it into a larger container also filled with water.

Outside of chemistry, glass test tubes are very common in biological and microbiological laboratories, where they are used to culture and store organisms. Plastic test tubes, which are just discarded after use, are also common in these sorts of labs. Glass test tubes are usually bought in bulk, and it’s pretty common to buy them in groups that also include rubber stoppers and racks to hold them in. Because of their extensive use, they are very easy to find.