All seams good: inside the world of leather upholstery

In contrast, a CNC stamping machine can be ready to punch perforations in the time it takes for a designer to create a pattern on a software package such as Adobe Illustrator or Autocad.

The CNC machine features two moving heads with five electronically controlled pins on each. The pins are interchangeable, come in five sizes and are fired into the leather working in a similar way to a fuel injector.

Changes to a design can be made very quickly. It’s not as fast as the traditional machines, but it can be used for small production runs.

For large runs, explains leather designer Debra Choong, “we use it more as a sample and prototyping tool, to test different patterns on their trims, but the intention would be for the hides to be produced on high-volume perforation machines”.

As well as flexibility of design, the speed of the system means customers can quickly check physical features, such as whether a new design works with a seat’s air-conditioning system.

“Traditionally, we might have to work out all the behind-thescenes aspects before we get to the final tooling, whereas now we can prototype a pattern, try it out, see whether it works with the airflow or not and check that it passes the customer’s test criteria on our leather,” says Choong. “If we need to make changes, like if the holes are too big, small or close together, we can modify it almost instantly.”

Practicality plays a big part, too. White leather interiors are in vogue at the moment, but it faces a problem.

“Whereas once drivers of premium cars may have worn suits, now wearing jeans is commonplace, and the colour from the blue denim can stain white leather blue,” explains Muirhead.

Developing coatings capable of preventing that staining is one of the many unseen aspects of producing premium leather, and an in-house test laboratory is equipped with rows of specialised test rigs exhaustively checking how the leather copes with rubbing, water, sunscreen, alcohol, alkalines and stretching, plus how flexible it is.

Fogging tests establish how much leather contributes to humidity and the fogging of a car’s windscreen, there are shrinkage tests to establish suitability of certain grades for different uses, whether it’s on the upper instrument panel or a seat, and leather has to resist fading in ultraviolet light. The hides used to make leather are a waste by-product of the food industry. Muirhead is quick to stress that no animals are specifically farmed for making it.

It’s so tough and long-lasting that Bridge of Weir’s sister brand, Muirhead, counts Ryanair as one of its many aviation customers, the budget airline having worked out that the robustness of its leather makes it less costly than cheaper alternatives. As part of the Scottish Leather Group, Bridge of Weir is certified as meeting a raft of environmental standards and recycles the 2000 tonnes of water that it uses daily.

It’s also on course to become carbon-neutral by 2025, thanks in part to a bespoke gasification plant (designed by the group’s head of sustainability and innovation, Warren Bowden) that turns waste products into sustainable energy.

After almost 120 years, Bridge of Weir’s craft has evolved from old-school to high-tech. And with a client list that includes Aston Martin, Bentley, Jaguar, Land Rover, Lotus, McLaren, Polestar and Volkswagen, it’s clearly still at the top of its game.

Leather legends