Leather and fur have long borne the brunt of the criticism of animal products in fashion, but silk usually gets a free pass. Even Stella McCartney, who is often heralded by vegan fashionistas, is still a frequent lover of silk in her designs.

Silk is a lot more common and harder to avoid than other more obvious animal products. Conventional silk isn’t wildly expensive, so it frequently pops up in blends with cotton or cashmere at mid-tier stores like Banana Republic and Martin + Osa.

However, the advent of the green fashion movement has opened some doors for people who want to wear silk without harming the silkworms who create it. Of course, for ethical vegans — the people who eschew not just leather and fur but wool and pearls as well — there’s no difference between silk and wearing the pelt of your favorite pet, so synthetics remain the only avenue.

If you’re interested in what’s new with this ancient textile, read on.

Conventional silk

Under even natural circumstances, the silkworm has a short life of only two months, most of which is spent eating. They feed on white mulberry leaves until they have shed their skin four times and have reached full size. It takes just a few days for each silkworm to spin its cocoon.

At this point, conventional silk farmers will boil the cocoons to kill the moths and harvest the cocoons. A typical cocoon yields up to 3,000 feet of continuous silk thread, and it takes approximately 2,600 silkworms to produce a pound of silk fabric. Industry analysts estimate the world’s production of conventional silk is as much as 70 million pounds per year.

Peace silk

Peace silk — also known as vegetarian silk — is made from cocoons that have been collected after the moths have hatched and flown off. Just before hatching, the moth secrets an acidic chemical that weakens the thread allows it to tear a hole in the cocoon. Because the thread is torn when the moths emerge, peace silk thread cannot be unwound in a single continuous piece as conventional silk thread is. It instead has to be broken down and spun like wool. The result is a thicker and loftier weave with some color irregularities.

Wild silk

Also known as Tussah silk, wild silk is spun from cocoons that are found in fields instead of commercially grown on farms. Because the diet of wild silkworms is more varied in nature, this type of silk is usually beige or brown and must be bleached to obtain lighter colors. Similar to peace silk, the finished product tends to be fluffier.

Both wild and peace silk have slowly been catching on among designers. In particular, Norwegian label Fin has been pioneering designs that use the fabric.

Rayon

Originally called “artificial silk,” rayon was developed to mimic the luster and slip of the real thing without the use of silkworms. According to Ohio State University, it was the first synthetic fabric, created in the 1890s from wood pulp. It is not a petroleum-based textile like polyester, but processing requires large amounts of water and energy, which is to blame to substantial air and water pollution. Because of its low cost, it frequently is used to make lower-quality garments.