Cotton-based elasticised yarns to make environment-friendly elasticised fabrics

A method for making an elastic core yarn comprising the steps of:

• prearranging a source of an elastic core comprising an elastic fiber made of a natural rubber containing more than 80% of cis-1,4-polyisoprene, wherein said elastic fiber has an elastic fiber linear mass density set between 200 dtex and 1000 dtex;
• prearranging at least one covering yarn comprising cotton at a weight percentage higher than 50%, wherein said covering yarn has a covering yarn linear mass density set between 6 Nm and 100 Nm, said covering yarn prearranged with an initial twist direction selected between “Z” and “S”;
• conveying said elastic core and said covering yarn up to a collecting spool, at a predetermined elastic core conveying speed and at a predetermined covering yarn speed, respectively, wherein:
• said elastic core conveying speed ranges from an initial elastic core conveying speed, at said source of elastic core, to a final elastic core conveying speed at least twice said initial elastic core conveying speed, at said collecting spool, and
• wherein said step of conveying is carried out in such a way that said covering yarn laterally attains a proximity of said elastic core in a wrapping space;
• and
• helically wrapping said covering yarn about said elastic core in said wrapping space, thus obtaining said elastic core yarn;
• wherein:
• said elastic core conveying speeds and said covering yarn conveying speed are selected in such a way that, in said step of helically wrapping:
• said covering yarn becomes twisted with a final twist direction opposite to said initial twist direction;
• a number T of coils of said covering yarn set between a predetermined minimum value T0 and a predetermined maximum value T1, said minimum and maximum values T0,T1 depending upon said covering yarn linear mass density, is wrapped about one length unit of said elastic core yarn, and
• said wrapping space is a protected space enclosed by a container.