How indium closes the microscopic gaps
A glass surface can look perfectly smooth and still have tiny ridges and hollows. A rigid seal may touch only the highest points, leaving narrow paths for gas to leak through. Indium solves that problem by yielding under pressure: its atoms can shift past one another, letting the metal flatten and flow into the surface’s small imperfections.
In a typical seal, a strip or ring of indium is compressed between the glass and another surface. The metal deforms where it meets each side, increasing the area of close contact and blocking the connected gaps that gas could travel through. The result is a mechanical seal, not a glue bond: the metal is held in place by the joint’s pressure and shape.
Why softness matters in vacuum equipment
A vacuum seal must prevent even very small amounts of gas from entering a space where pressure is kept low. Indium’s ability to conform helps make that possible without heating the glass or adding adhesive. That can be useful when a joint must remain compatible with temperature-sensitive parts or be assembled without a high-temperature process.
The same softness also sets a limit. Indium can be squeezed or damaged if the joint is overloaded, so the surrounding hardware must apply and retain the right compression. The seal works because the metal gives way locally while the rest of the assembly keeps it confined—turning a soft material’s weakness into a way to shut off microscopic leak paths.
