So technically demanding is the sealing process that the company had to create its own welding expertise no supplier was up to the task.

ECONOMIST: Espresso coffee

Meanwhile, the FBI is continuing the process of sealing off and boarding up the areas near the home of the alleged captor that they have checked for evidence.

CNN: Mystery surrounds freed Cleveland captive

In 1998, Lawrence Berkeley National Laboratory physicists Max Sherman and Lain Walker tested a variety of sealing materials on sheet metal ducting, then heated and cooled the ducts to simulate the aging process.

FORBES: Magazine Article