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*"Closed-tube tests" mean the tube is closed at only one end. "Open-tube tests" mean the tube is not closed at either end (in other words, it's just a section of glass tubing, usually bent to keep the sample from sliding out).
 Larger test tubes allow the sample to contact too much air to be useful in "closed-tube" tests.  A piece of glass tubing with one end fused shut can also be used in the closed-tube test.  Never heat a tube that's sealed at both ends!

Please be sure to read about proper heating of test tubes. 

Most popular test tube size?
They are all about equally popular.  15x125 has a slight edge over the rest.
Each size has its merits.  The 25x150's are good for lecture hall demonstrations, for example;  more liquid means color changes can be seen at a greater distance.

CR Scientific

Test Tubes

We sell the style traditionally used in chemistry;  these have a rim or lip.
Rimless tubes are normally called culture tubes.

Quick links:
10 x 75 mm
12 x 75 mm
13 x 100 mm
15 x 125 mm
18 x 150 mm
25 x 150 mm

10 x 75 Test Tube with Semimicro Test Tube Clamp
Test tubes, 10 x 75 mm, borosilicate.  Excellent for micro and semi-micro chem experiments. Can also be used for closed-tube* tests of minerals.
Please read our safety notes for proper heating of test tubes.
The semi-micro clamp (listed below) is good for these small test tubes.

#330-72. Test tube, 10 x 75 mm, 72 each......................$20.95


Test tubes, 12 x 75 mm, borosilicate.  This size will fit the smaller sleeve inserts provided with the Ultra 8 series centrifuges. This is the smallest test tube diameter for which we have rubber stoppers available (takes #000 stopper, avail. in solid only).  These test tubes will fit in our #C1318 and #C1331 racks.

#331-72. Test tube, 12 x 75 mm, 72 each......................$22.95


12x75 test tube in the centrifuge rotor
The 12x75 tubes will fit the smaller sleeves provided with the Ultra 8V.

Test tubes, 13 x 100 mm, borosilicate. This is the size that was in many of the old chemistry sets (Skil-Craft, etc.).  Takes #000 stopper (avail. in solid only).  
These tubes fit in our #C1518 racks.

#332-72. Test tube, 13 x 100 mm, 72 each.............$23.95


Test tubes, 15 x 125 mm, borosilicate. This is the smallest test tube size for which we have 1-hole stoppers available (size #00 stopper). 
These tubes fit our #C1518 racks.

#333-72. Test tube, 15 x 125 mm, box of 72.............$26.95


Individual test tubes... when we have an open carton.
#33372-EA. Test tube, 15x125 mm, by the piece.........50 cents ea.


Test tubes, 18 x 150 mm, borosilicate glass. Indispensable for all-around lab work.  This is the smallest test tube size for which we have both 1-hole and 2-hole stoppers available (size #1 stopper).
The 18 x 150 has been the standard size laboratory test tube for many years, although some modern labs are using smaller tubes to conserve reagents and generate less waste.
Inside Diameter:  between 15.5 and 16.5 mm.
Capacity (max.) about 25 mL

#334-72. Test tube, 18 x 150 mm, box of 72.............$32.95


Test tubes, 25 x 150 mm, borosilicate glass.  The largest size of test tube we carry (this is about 1 inch diameter by 6 inches long).  Takes #4 stopper. Capacity: (maximum) about 50 mL.
Sold by the dozen.

#336-06. Test tube, 25 x 150, 1 dozen ea..............$14.99


Clamp, test tube, brass

Test tube clamp, Stoddard type, with finger grip.  May be brass or nickel steel.  Works with 12 mm and larger test tubes.
#C73.......$1.70 ea.


Test tube clamp, semimicro
Test tube clamp, Brass, Semi-Micro - made for extra-small test tubes (e.g., 10x75, 12x75).
#C35.........$1.39 ea.


Clamp, test tube, wooden
Test tube clamp, Wooden - resembles a clothespin but is made specially for holding a test tube during heating.  Economical.  Doesn't conduct heat to the hand (but will of course char if directly exposed to flame).  Works with 12 mm and larger test tubes.
#C70.........Temp. unavailable.  We stopped carrying these since the quality went way downhill.  We are trying to get decent ones again.

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