The making of a fish leather shoe: From oceans to forests

Originally published in BC Forest Professionals magazine

7 Leagues boots on a sunny day in East Vancouver. Photo credit: Tasha Nathanson.

What do Nike, BMW, Prada, Christian Dior, and Louis Vuitton have in common? Using leather from fish skin. It’s a new-old material increasingly used for its low environmental impact, high beauty, and durability.

Leather and shoemaking aren’t industries FPInnovations was associated with in the past. But in an era where interconnectivity is everything, FPInnovations’ and 7 Leagues’ paths were meant to cross. In British Columbia, forest and sea are bound to meet.

When 7 Leagues — a Pacific Northwest fish leather tannery and high quality boot maker — approached FPInnovations — a research and development organization specializing in solutions in support the global competitiveness of Canada’s forest sector — in 2019, the need was clear: obtain a high-quality plant-based tannin to craft leather and shoes out of local and sustainably sourced fish skin. Tannin is a naturally occurring compound used in the production of leather, rendering it pliable and durable. In this case, the tannin would be used to create leather from fish skin and, for 7 Leagues, specifically from sustainably caught wild salmon.

Why fish leather?

7 Leagues is participating in a growing trend within the fashion industry toward more environmentally, socially, and ethically conscious production. Fish skin has a unique pattern and, despite being thin, it’s stronger per thickness than mammal leather because of its crisscrossing fibres. The fish skin is a byproduct of the food industry that often goes to waste; using the whole fish adds value to fisheries, reduces waste, and makes good sense.

The craft of making fish leather has been around for centuries in First Nations, Arctic territories, and across Asia and Europe. It’s now making a comeback as an emerging commodity in the world of high-end fashion, just done a little bit differently. Rejuvenating the craft of fish leather tanning in BC showcases the ingenuity of a past practice and its adaptability to present-day innovation.

Smoked sockeye salmon tanned with Western Hemlock. Photo credit: Tasha Nathanson.
Obstacle as opportunity

Historically, tannin from bark has been the most common way to preserve skin, even giving the practice its name: tanning. As modern manufacturing shifted to faster and cheaper methods, a toxic chemical solution of chromium salts overtook plant-based leather production in all but the high-end of the market. Plant-based tannins make stronger leather, but chrome requires less time, money, and skill.

By the 1950s and 60s, local hemlock bark tannin could no longer compete with chrome-tanned leather. Eventually, BC’s last hemlock tannin plant closed. Chromium salts used to tan about 90 per cent of leather today are harmful to the environment and to tannery workers. As North America tightened regulations, chrome tanning was squeezed out almost entirely.

Seeking a local solution
Westen Hemlock bark.

With sustainability in mind, the search for a local eco-friendly tannin to make fish leather began. The only commercially available tannin extracts 7 Leagues could find, however, were imported. Since importing tree products to BC is like importing sand to the Sahara, this seemed like a problem that could be solved with a homegrown solution.

Research projects led by FPInnovations on wood species in Canada revealed tannin concentration are highest in western hemlock, western larch, and black spruce. Some bark extracts even show antimicrobial activity against pathogens and strong antioxidant activity. Western hemlock extract was one of the best candidates.

The worthy evergreen Western Hemlock
Westen Hemlock.

Western hemlock is the most plentiful tree species in coastal BC. While its wood finds applications in the general lumber industry, its bark is used as biofuel in pulp mills along the coast. Declining demand for traditional paper products such as newsprint is generating an increase in hemlock bark availability. This newly available bark needs new and ideally higher-value applications like tannin extraction.

Trying to get more value out of bark, seen as a low-value byproduct, made perfect sense. In fact, BC’s Ministry of Forests, Lands, Natural Resource Operations and Rural Development launched the Coast Forest Sector Revitalization Initiative in 2019 to, among others, increase the processing of BC logs and reduce residual waste fibre left in the woods.

Western hemlock bark is generally found as a waste product at the mill site as well as at sort yards, which are often situated near Indigenous communities. Bark is mostly available as debris and waste, but with proper sorting and managing, it can be accessible at very little cost. This presents an opportunity to work with Indigenous communities to develop a circular economy forest-based business.

The not-so-secret recipe

The first tannin extraction method used ethanol and elaborate equipment; work which required strictly controlled conditions and safety measures. Initially, the process was used to evaluate the feasibility of tannin extraction from bark and assess its quality. In this test, hemlock showed great potential when compared to other species.

Western Hemlock tannin – from crushed bark to tannin solution.

Further effort focused on finding an environmentally friendly kitchen-type extraction protocol that doesn’t use too much equipment. It uses water as the sole solvent in the process and yields similar quantity and quality of tannin as when using ethanol. This new method could potentially be used by coastal Indigenous communities and others interested in extracting tannin from bark at a relatively small scale.

FPInnovations reached out to several coastal Indigenous communities to better understand their traditional knowledge. Learnings highlighted that although fish leather was traditionally oil tanned, most other leather had been tanned using animal brain and hemlock bark, the latter giving it a distinctive red color.

What’s next?
Freshly tanned coho salmon leather drying on a rack. The first two rows are made with Western Hemlock. Photo credit: Tasha Nathanson.

We’re very happy with the results of the hemlock tanned fish leather. Tests yielded a striking red colour and woodsy perfume, making a distinctive and wholly Cascadian leather that stands out in the international market. 7 Leagues hopes that commercial production of hemlock extract will be forthcoming soon, as they’d love to add this offering to their product line.

Better yet, if FPInnovations’ Indigenous community partners choose to bring hemlock tannin extract to market, it would be yet another way of using business as a force for good to knit the social, environmental, and economic needs of BC through a wholesome use of local resources.