Method of manufacturing a bladder element with an impression of etched area of mold assembly and article having bladder element with impression

An article of footwear comprising:

• an upper;
• a sole assembly secured to the upper and including a midsole and an outsole;
• wherein:
• the midsole includes a fluid-filled bladder element including a first polymeric sheet that has a surface with an impression;
• the fluid-filled bladder element further including a second polymeric sheet bonded to the first polymeric sheet at a peripheral seam so that the fluid-filled bladder element defines a sealable internal cavity that retains fluid;
• the first polymeric sheet comprises a gas barrier polymer and has a first thickness;
• the impression comprises a recess in the surface of the fluid-filled bladder element;
• the impression has a maximum depth into the first polymeric sheet of not more than about one-half of the first thickness such that the gas barrier polymer is not compromised by the impression;
• a first portion of the fluid-filled bladder element with the impression is exposed to view through one of the midsole, the outsole, or the upper;
• and
• a second portion of the fluid-filled bladder element is blocked from view by said one of the midsole, the outsole, or the upper.