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:
“Ice is an interesting subject for contemplation. They told me that they had some in the ice-houses at Fresh Pond five years old which was as good as ever. Why is it that a bucket of water soon becomes putrid, but frozen remains sweet forever? It is commonly said that this is the difference between the affections and the intellect.”
—Henry David Thoreau (1817–1862)
“To round that shell’s elaborate whorl,
Adorning every secret track
With the delicate mother-of-pearl,
Made the joints of Heaven crack....”
—William Butler Yeats (1865–1939)