Koeputki

Koeputki, Finnish for test tube, is a slender cylindrical container used in laboratories to hold, mix, or heat small quantities of liquid. They are typically made of glass or plastic, open at the top and closed at the bottom, with a rounded or flat bottom. Glass tubes are usually borosilicate for chemical resistance and thermal stability, while plastic variants such as polypropylene or polymethylpentene are common for disposables and biological work. Sizes vary; common lengths are about 75–125 mm and diameters around 10–20 mm.

Koeputket come in several variants. Straight test tubes may be sealed with stoppers or caps for storage or sterile work; boiling tubes are designed to withstand higher temperatures; culture tubes are intended for incubation with closures. Some tubes have ground glass joints or side arms for connections in more advanced setups.

Uses: They are used for qualitative and quantitative experiments, mixing reagents, heating small samples on a flame or hot plate, and observing reactions, color changes, or gas evolution. They are also employed in educational settings to demonstrate basic laboratory techniques and in research to handle small-scale reactions.

Safety and handling: Use appropriate tongs or racks when heating; avoid thermal shock by gradual temperature changes, especially with glass. Clean and sterilize as required; dispose of used tubes according to local regulations. In Finnish contexts, koeputki is the standard term for this basic piece of laboratory glassware, found in classrooms, research facilities, and industrial labs.