Glass Test Tubes

Glass test tubes are for heating small amounts of a solution, running ion and precipitation tests and growing cultures. We sell them singly or in bulk with no minimum order, in sizes from 10 x 75mm up to 25 x 200mm.

Borosilicate 3.3 glass is the one to heat. It takes a direct Bunsen flame and sudden temperature changes without cracking, and it can go in the autoclave. We stock it with a rim, without a rim, with a heavier 1.2mm wall, and with polypropylene screw caps for storing samples.

Soda-lime glass costs much less and is fine for mixing, precipitation tests and demonstrations where the tube isn't heated hard. It comes rimless in 12 sizes, including the 16 x 150mm tube most school labs use and 25 x 150mm and 25 x 200mm boiling tubes.

A rim gives a clamp or test tube holder something to hold and protects the mouth from chipping. Rimless tubes take caps and plugs more snugly and store more compactly. Our rimmed borosilicate tubes fit RS7 (16mm) and RS13 (25mm) rubber stoppers.

We ship from our Boksburg warehouse to anywhere in South Africa. Running precipitation reactions this term? Our Grade 10 precipitation and ion tests guide sets out the combinations, the observations and the results table.

Rows of empty test tubes in racks on a laboratory bench

What is a Glass Test Tube?

A glass test tube is a simple cylindrical vessel, closed at one end and open at the other, used for holding, mixing, heating, and storing small samples. Borosilicate glass 3.3 test tubes have a very low coefficient of thermal expansion, resisting sudden temperature changes, and are resistant to most acids, alkalis, and solvents. They can be autoclaved and heated directly over a Bunsen burner. Soda-lime glass tubes are more affordable for general use where heat or chemical exposure is not a factor. Rimmed tubes have a rolled lip for clamps and stoppers; rimless tubes have a fire-polished opening for easy stacking. Round-bottom tubes distribute heat evenly; flat-bottom tubes stand upright without a rack.

Common uses of laboratory glass tubes in the lab

From growing cultures to serial dilutions, heating reactions, and colorimetric analysis, glass tubes are the workhorse of individual sample handling across every scientific discipline.

  • Test tubes of coloured culture media in a wire rack

    Culture and microbiology

    Test tubes and culture tubes are the standard vessel for growing microbial cultures, performing broth dilution series, and incubating biological samples. They can be fitted with loose-fitting caps or cotton wool plugs to allow gas exchange, and can be autoclaved repeatedly for sterile reuse.

  • A gloved hand pipetting red solution into a rack of test tubes

    Serial dilutions and sample preparation

    Glass test tubes are the preferred vessel for serial dilutions in microbiology, clinical pathology, and analytical chemistry. Their uniform bore allows accurate pipetting, and a rack of identically sized tubes allows multiple dilution factors to be prepared simultaneously.

  • A gloved hand heating a test tube over a Bunsen burner flame

    Heating and chemical reactions

    Borosilicate glass tubes withstand direct Bunsen burner flame for heating small liquid samples, dry distillations, and qualitative chemical reactions. Boiling tubes have a thicker wall for more vigorous heating applications.

  • A row of numbered Nessler tubes holding graded coloured solutions

    Colorimetric comparison

    Nessler tubes are tall flat-bottomed glass cylinders for visual colorimetric analysis, where an unknown sample is compared against concentration standards viewed through the liquid column. Used in water quality testing, ammonia determination, and environmental monitoring.

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