On Jan. 26, 1939, the San Francisco Chronicle introduced its readers to a new material that, though they didn’t know it at the time, would soon envelop them from toe to head. An article reported that the du Pont Co. was building a plant to turn its new coal-based fabric, “nylon,” into stockings. Fashion editor Ninon (one word!) gushed, “When a gossamer sheer stocking can be worn every day for five months before it springs a hole, that’s news!”

Three-quarters of a century later, our closets are filled with nylon and other plastic fabrics — and a similar revolution in materials may be at hand. Instead of coal and oil, these new fibers, fabrics and leathers are made with genetically engineered microbes. The first generation of companies to harness yeasts, bacteria and fungi to make clothing may have originally set out to mimic silk and leather. But they’re quickly finding they can do much more.

At the office and laboratory of Geltor, located above a big-box hardware store in San Leandro, founders Alex Lorestani and Nick Ouzounov hand me several pieces of leather. One tiny square is as thin and white as vellum. Another resembles a stiff brown belt. A third piece, golden and translucent, I can’t stop touching. It stretches as if someone had managed to infuse cowskin with rubber.

The 3-year-old startup ferments yeast cells that are genetically programmed to synthesize animal collagen, the primary protein in skin, cartilage and tendons. Geltor is preparing to sell collagen to the cosmetics industry, but also plans to turn it into vegan, food-grade gelatin and leather.

Rethinking how leather is produced gives designers all sorts of room to play.

“Cows come in pretty standard sizes,” Lorestani says. If a cow was the size of a conference room, what could you do with that unbroken, unscarred expanse of skin?

The scrap I’m fondling isn’t even from a giant virtual cow. It’s a proof of concept, a sheet used to bind a copy of Paul Shapiro’s 2017 book “Clean Meat,” about the cultured meat industry. And the collagen used to make it has the same molecular structure as jellyfish.

The sample sets the imagination spinning: Why does leather have to come from a cow or an alligator? Can we custom-create leathers to conform to our needs?

“Design, as we’ve seen it, is something that happens at the end of the process, when you’re handed a material off the shelf,” says Suzanne Lee, chief creative officer at Modern Meadow in New Jersey and the founder of Biofabricate, a 5-year-old conference on these new materials. “What biofabrication technology allows for is that design can start right at the beginning.”

Modern Meadow started off making “steak chips” grown from bovine cells, but switched to cultured leather from bioengineered yeasts. In the fall, the company displayed its biofabricated leather, branded Zoa, at the Museum of Modern Art and a New York pop-up shop.

Zoa is based on bovine collagen. But that doesn’t make it an exact substitute for cow leather. “We could create a two-dimensional sheet on a roll,” Lee says. “But we can also paint with it, we can spray it, and we can integrate it with other textiles. The creative toolbox becomes super interesting, and far beyond what you could do with a traditional animal.”

The most popular prototype at Modern Meadow’s pop-up in New York was a swath of (traditional) silk with nanofibers of collagen sprayed onto it in big circles. The texture of the combined fabrics was “like nothing I’d ever felt,” Lee says.

The field of biofabricated materials is in its early days.

Neither Geltor nor Modern Meadow have any products on the market. While MycoWorks (based in San Francisco), Ecovative Design and Grand Zero Espace are making leathers from cultured mycelium — the fibrous, vegetative part of a fungal organism — only the latter company is selling small pieces of its MuSkin products to the public.

In 2016, North Face sold limited quantities of a $1,000 Moon Parka made with spider silk biofabricated by a Japanese company named Spiber— but only in Japan. In December, San Francisco’s Bolt Threads put up for sale 100 knit caps whose yarn was a blend of merino wool and cultured spider silk, and they disappeared almost immediately. (Bolt just announced it will be taking orders for a bag made of mycelium leather, produced with Ecovative, in June.)

AMSilk is responsible for the next biofabricated clothing item customers may be able to buy: a running shoe from Adidas whose upper is woven from its Biosteel spider silk.

According to company CEO Jens Klein, the shoe isn’t just biodegradable or, well, cool. The silk protein that AMSilk cultures from bacteria and spins into fibers offers numerous performance advantages: It’s lighter and better at wicking moisture away from the foot, and may be less likely to collect bacteria on its surface. Plus, he adds, “It’s better feeling.”

Why spiders, when traditional silk is such a luxurious fabric?

“Silkworm silk is not something that yields really any performance,” Klein says. Given spider silk’s elasticity and strength, AMSilk is finding other uses for the protein in liquid form, such as cosmetic creams, and is culturing green lacewing silk whose stiffness may eventually make it a good analog for Kevlar.

Building the infrastructure to biofabricate fabrics and leathers — and do it affordably — may be the major hurdle right now, just as it was with nylon stockings in 1939.

“The challenge isn’t that the market isn’t ready for (these materials),” Lee says. “There’s huge demand from the fashion industry.”

From customers as well. “This is a new, emerging category of materials that may give me what I love about an animal product — the look, the feel — but an animal hasn’t lost its life in order for that to happen,” Lee adds. “Or I don’t want to use a plastic material that is going to sit in a landfill for the next hundred thousand years.”

“The most efficient solution to getting there is not around the existing class of materials,” Geltor’s Lorestani says. “It’s around new features in the tree of life that haven’t been explored.”

Jonathan Kauffman is a San Francisco Chronicle staff writer. Email: jkauffman@sfchronicle.com. Twitter and Instagram: @jonkauffman