The patent relates to the field of metallurgical products and comprises a cylindrical body (15) provided with a plurality of slots (16), with a taper "A" designed such that the larger opening (18) is at the outer surface of the breather (15) and the smaller opening (19) is located internally with respect to the breather (15), so that the aluminium component (5), when removed from the mould (6), brings with it the burr (17), leaving the slots (16) of the breather (15) always free, and also a breather (29) comprising a cylindrical body constituted from a plurality of holes (21), with a conicity "A" designated such that the larger opening (22) is at the outer surface of the breather (20) and the smaller opening (23) is located internally with respect to the breather (20).