a plastic container having a thin outer layer that protects against stress concentration effects arising from either surface irregularities or flexing when dropped and a method of making that container . the outer layer helps avoid bottle failure resulting from cracks that start at such areas of stress . the outer layer may incorporate both the stress inducing irregularities and the properties to minimize possible , resulting catastrophes . the surface irregularities giving birth to stress include edges of in - mold - applied labels , ridges , stippling , and grip bumps . dropping the container gives rise to flexing which can also induce stress concentrations . the outer layer , to accomplish the protective function , should display lesser brittleness or , in some cases , lesser density than the bulk of the container wall . making the container involves forming the bulk of the wall with a first , inner , structural plastic . a thin layer displaying lesser brittleness or , in some cases , lesser density is formed as the container &# 39 ; s outer layer .