Frozen Joints
Sometimes conical ground glass joints can lock together, preventing the user from rotating them - this is known as freezing or locking. Ball and socket-type joints are much less susceptible since they have more degrees of rotation than conical joint. This may happen for a variety of reasons:
- Lack of lubrication between the two glass surfaces. If organic solvents come into contact with the joint, they can slowly dissolve the grease, leaving a dry glass-glass surface.
- Exposure to a strong base (hydroxide, phosphate, etc) may dissolve some of the SiO2 surface, generating silicic acid (H4SiO4 / Si(OH)4)
- Solids from reaction mixtures
- Allowing sealed vessels to cool, which creates a pressure difference across the joint
Frozen joints may be removed by working solvent into the joint while rocking the stopper, heating the outer joint, or cooling the inner stopper. The last two methods employ the property of thermal expansion to crease a small space between the two surfaces. There are also specialized glassblower tools to unfreeze the joint.
Read more about this topic: Ground Glass Joint
Famous quotes containing the words frozen and/or joints:
“When icicles hang by the wall,
And Dick the shepherd blows his nail,
And Tom bears logs into the hall,
And milk comes frozen home in pail;
When blood is nipped, and ways be foul,
Then nightly sings the staring owl:
Tu-whit, tu-whoo!—
A merry note,
While greasy Joan doth keel the pot.”
—William Shakespeare (1564–1616)
“Opinions are to the vast apparatus of social existence what oil is to machines: one does not go up to a turbine and pour machine oil over it; one applies a little to hidden spindles and joints that one has to know.”
—Walter Benjamin (1892–1940)