How is bubble wrap made? --- Anna, Philadelphia, Pa.
Bubble wrap is the famous plastic cushioning material made of sheets of plastic with thousands of raised bubbles on the surface. Kids love bubble wrap because it is fun to pop the bubbles.
To make bubble wrap, you need two sheets of plastic. One sheet can be placed over a form with holes in it - one hole for each bubble. The you apply a little suction to the holes to pull in the plastic and form the bubble shape. Another piece of plastic is laid over the bubbles and heated to seal the air in.
The only problem with this approach is that a thin sheet of polyethylene is not particularly good at keeping air molecules inside the bubble. In the same way that a rubber balloon loses air over the course of a few days, bubble wrap made of pure polyethylene can lose air as well. So some manufacturers may include another layer of plastic that is better at keeping the air molecules in.