Hermetic Sealing
A thin layer of PTFE material or grease is usually applied to the ground-glass surfaces to be connected, and the inner joint is inserted into the outer joint such that the ground-glass surfaces of each are next to each other to make the connection. The use of this helps to provide a good seal and prevents the joint from seizing, allowing the parts to be disassembled easily.
Sealing allows chemists to easily see when a taper is leaking, as bubbles can usually be seen flowing through the taper.
Both PTFE tape, bands, and fluoroether-based grease or oils, but not silicone-based, all emit hydrogen fluoride fumes as they approach and exceed their working temperature limits, which can occur when using a hotplate, mantle, oil bath or flame. Upon contact with moisture, including tissue, hydrogen fluoride immediately converts to hydrofluoric acid, which is highly corrosive and toxic, and requires immediate medical attention upon exposure.
Read more about this topic: Ground Glass Joint
Famous quotes containing the word sealing:
““The time has come,” the Walrus said,
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Of shoes—and ships—and sealing wax—
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And why the sea is boiling hot—
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—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)