How bubble wrap is made

Bubble wrap began as a failed plastic wallpaper.

stations: 5
things upstream: 7
raw sources: 3
steps from the ground: 5

The short version

Polyethylene beads are melted and squeezed into two thin films, with a barrier layer built in to hold air. One film is sucked into a drum full of tiny holes so it puffs into bubbles, and the second film is bonded flat across the back. The seal traps a pocket of air in every bubble.

Melt the resin beads

Polyethylene beads about the size of pea gravel drop into an extruder, a long heated barrel with a screw inside. Heater bands and the friction of the screw turn the beads into a liquid.

barrel at about 180 degrees

Goes in
Polyethylene
Squeeze out two films

The melt is pushed out of the machine as two stacked sheets of clear film. Plain polyethylene lets air creep out, so a barrier that holds air is sealed inside the plastic as it is extruded. Early makers coated the finished film with Saran instead.
Suck one film into a drum

One film wraps around a drum punched with holes. Suction through the holes pulls the soft plastic down into each one, and every dimple becomes a bubble.
Seal the flat film on

The second film is pressed over the first. Where the two stick together, air is trapped in each dimple.
Wind it on rolls

The finished sheet is wound into rolls. Small bubbles suit light items, and larger bubbles absorb more shock for heavier ones.

End of the lineBubble wrap

Worth repeating

Alfred Fielding and Marc Chavannes made it in 1957 while trying to create a three-dimensional plastic wallpaper.
One of the first big uses came in 1960, when IBM 1401 computers were shipped in it.
The most common bubble size is about 1 centimeter across.