Over-wrapping envelope for filter bags and method of forming a package with over-wrapping envelope

An over-wrapping envelope containing a filter bag for an infusion product, of the type such as tea in powder or leaf form, the over-wrapping envelope comprising:

• a sheet of over-wrapping material made of paper folded into a “U” shape along its transversal axis around the filter bag in such a way as to have two parts of the sheet of over-wrapping material superposed with interposed said filter bag, said sheet folded into a “U” shape having peripherally two longitudinal flaps parallel to each other, a transversal bottom flap at the folding of the “U” shape sheet and a transversal top flap parallel to the bottom flap;
• characterised in that it also comprises:
• a first and a second closing track, parallel to each other, formed by grooves along the respective lateral edges of the two longitudinal flaps of the folded sheet, said first and second tracks being obtained by mechanical deformation of the two superposed parts of the sheet at the respective longitudinal flaps;
• and
• a third closing track formed by grooves along the transversal top flap, said third track being obtained by mechanical deformation of the two superposed parts of the sheet at the transversal top flap.