Test Tubes

Also known as culture or sample tubes, test tubes are a common piece of laboratory glassware made of clear plastic or glass tubing with a rounded U-shaped bottom. There are a multitude of lengths and widths but the most common are 10-20mm wide and 50-200mm long. Tubes are usually made from borosilicate glass or fused quartz so they can be placed over a source of heat. They are very resilient and can stand temperatures up to 300 degrees centigrade. As well as being round-bottomed, some test tubes can be flat-bottomed or conical-bottomed. Some can have a ground glass stopper or screw cap and some have a white glass area for labelling the samples with pencil. If they need to be heated, glass is preferred. Otherwise for culture tubes, they are made of polystyrene or polypropylene which are discarded after use. Plastic test tubes with a screw top are also called falcon tubes. Some may have prepared contents. For example, a blue top tube of 5ml could contain sodium citrate as an anticoagulant for medical testing. Test tubes are essential pieces of laboratory equipment used for the handling and culturing of all kinds of live organisms as well as storing samples of blood and other fluids.