Loosening or tightening the construction of the fabric results in a higher or lower weight, as does the yarn size. Ordinarily, a lighter fabric woven with a finer, softer yarn hangs better and has a tighter surface while a heavier-weight shirt constructed with heavier yarn is more open.

The best way to manufacture a good-looking fabric is to keep a relatively tight stitch construction and change the yarn sizes for weight changes.

–Tim Harris, Delta