What actually happens to a retired airliner
Retirement is a teardown, not a scrapyard. Here is the sequence.
An airliner is almost never retired because it is worn out. It is retired because the arithmetic changed.
The economics come first
Airframes are certified for a design service life measured in pressurisation cycles - every climb and descent flexes the fuselage a little. But most aircraft leave service long before they approach that limit. A newer type burns less fuel, a heavy maintenance check comes due, a lease ends, or demand on a route collapses. At some point the cost of another year exceeds the value of another year, and the aircraft flies to a teardown facility.
Teardown, not scrapping
What follows is disassembly, not demolition. A modern airliner contains thousands of serialised components with their own logbooks and their own remaining life: engines, auxiliary power units, landing gear, avionics, actuators, seats. These are removed, inspected, recertified and returned to service on other aircraft. A retired airframe keeps a fleet flying for years.
Then the structure
Only when the valuable, traceable components are gone does the structure itself get addressed - wings, empennage, and the fuselage with the airline's livery still on it. Most of that aluminium is recycled as raw metal, which is the point at which the paint, the rivet lines and everything else that made it that aircraft stops existing.
Which is where we come in
The skin is the only part that carried the aircraft's identity in the open, for its whole working life, visible from the ground. Once it is melted down, it is stock aluminium. Cutting pieces from it before that happens is the whole idea.