EThere is no such thing as bad weather, just wrong clothing, as the saying goes. But for the longest time in human history, there was basically only wrong clothing. Whether in the Stone Age, with the Romans or in the Middle Ages: people could only arm themselves against rain with what nature directly provided. With a cloak of plaited straw, perhaps, or animal skin. There were certainly wishes left unfulfilled.

At some point, linen was coated with tar, and impregnation with linseed oil came up in the 18th century – and with it the beginnings of so-called oilskins. But this water-repellent coating did not offer permanent rain protection and had to be renewed regularly.

Against this background, the Scotsman Charles Macintosh (1766-1843) heralded a new era when he worked on coating fabrics with Rubber in the 1820s. On June 17, 1823, he received a British patent, later assigned number 4804, for his process of waterproofing fabrics.

Rubber is the pulp left over from drying the milky sap of rubber trees. Because rubber is sticky and therefore unsuitable as an outer Layer of clothing, for example, the Scotsman laid two layers of fabric coated in this way on top of each other to create a kind of sandwich structure – with the waterproof rubber layer in the middle. He then sent the whole thing over a roller, as he explained in his patent. He also listed there that the process works with wool, cotton, linen or silk as a material basis, among other things.

In the book “Noble Obsession”, which deals with the early experiments with natural rubber, the American author Charles Slack describes the invention. Until then, Macintosh was an industrialist producing chemicals in the Glasgow area. He also processed coal tar, which was left over from the production of lighting gas from coal. According to Slack, when processing it, the entrepreneur was left with a waste product: the solvent mixture naphtha. He found out that solid rubber is finely distributed in this liquid and can then be easily applied to fabrics.

In order to use the patented process commercially, he started a new company in Manchester with partners from cotton processing: Charles Macintosh & Co. The waterproof fabric was made into canvas, seaman’s clothing and, over time, air mattresses, rescue tires, cushions and bellows, among other things and made diving suits. And raincoats.

The special breakthrough came in 1843

But the beginnings were not that easy. As Slack points out in his book, the rubber layer between the fabric panels smelled bad and was sensitive to temperature. The coat fabric became stiff when it was cold, and lost its shape when it was too hot. Slack points out that early coats carried a warning to stay away from open flames.

It was Thomas Hancock in particular, first a process licensee and later a Macintosh partner, who solved these problems with a series of process improvements, which he describes at length in his 1857 book on the early English rubber industry.

A special breakthrough came in 1843. At that time, Hancock, almost at the same time as the American Charles Goodyear, was developing a way of linking the molecular chains in rubber with each other using sulfur units. This vulcanization converted the rubber, which was sticky and limp when hot, into solid and dry rubber. This solved many problems, and the outer layer of fabric was no longer absolutely necessary.

After that, Mackintosh coats – at some point a “k” crept into the name – were a successful product for more than a hundred years. British railway workers wore them, the military, and the general public also swore by a Mac or Mack, as it was soon called. It wasn’t until the second half of the 20th century that plastics such as polyvinyl chloride (PVC) started the decline of rubber rainwear.

The Rosenheim company Klepper also had to experience this. Your co-founder Johann Klepper had designed a kind of German Mac in the 1920s. Inspired by the waterproof rubber skin of the Klepper folding boats of the time, he worked on a raincoat made of rubberized cotton that came onto the market in 1926. Tack coats were common well into the second half of the 20th century, but they too lost ground when it became easier and cheaper to coat fabrics with a rainproof PVC. The waterproof coating of the Friesennerz, which was extremely popular in the 1960s and 1970s, was also made of PVC for a long time.

But regardless of whether it was Mac, Klepper or Friesennerz – in all cases wearers had to struggle with the fact that the rainproof caoutchouc, rubber or PVC layer was also impermeable to perspired moisture. A cape-like design was therefore supposed to ensure a certain exchange of air even with early Macintosh coats. Klepper, on the other hand, eventually sewed small air ducts into the back section to improve circulation. Materials that are inherently both rainproof and breathable were not known at the time.

How Gore created his Gore-Tex empire

Then came the American Robert Gore, who in 1969 created countless small pores in a film made of polytetrafluoroethylene (PTFE) by jerky stretching. These were small enough to be impermeable to water droplets but large enough to allow water vapor to pass through. The first items of clothing with this breathable Gore-Tex membrane came onto the market at the end of the 1970s.

Fabric on the outside, fabric on the inside, with a breathable membrane in between: That was the principle for the soon to be booming segment of outdoor clothing. Basically, this three-layer design wasn’t that far removed from Charles Macintosh’s approach – except that the layer of rubber between the two layers of fabric was still a real barrier to sweat from sweat. And she was a lot fatter. Modern membranes are thinner than a human hair.

After a few years, the microporous membrane faced competition from a membrane that functioned without pores. The moisture that is sweated out is released in certain zones of the membrane and then diffuses outwards along defined paths. “Both membrane types have advantages and disadvantages,” says René Bethmann from outdoor manufacturer Vaude. The breathability of the porous membranes is usually higher. However, the pores can also become clogged. Regular washing should prevent this, which in turn reduces the lifespan of the adhesive layers between the individual layers, according to the clothing engineer.

Something else is different in modern functional clothing than in the days of the Macintosh: For rain protection, the outer layer of fabric is usually impregnated to be water-repellent. This prevents the outer layer from getting wet and clammy, because the actual barrier for the raindrops is provided by the membrane underneath.

Water-repellent effect can decrease over time

For decades, this impregnation consisted of so-called fluorocarbons (FC), which belong to the PFAS (per- or polyfluorinated alkyl substances). Because many members of this group are toxic, polluting, and extremely long-lived, they are currently under pressure and likely to be banned.

“Several manufacturers are now using alternative impregnations,” says Boris Mahltig from the Niederrhein University of Applied Sciences. As examples, the expert for the functionalization of textiles cites “siloxanes, polyurethanes and so-called dendrimers, i.e. highly branched molecules”. However, Vaude expert Bethmann admits that the water-repellent effect of these alternatives lags behind that of FC coatings.

PTFE, the classic polymer for the Gore-Tex membrane, is also a PFAS. However, Gore now also offers a fluorine-free alternative made from polyethylene. But why add a membrane when the outer layer of fabric has a water-repellent coating? “Water-repellent doesn’t mean waterproof,” explains Bethmann. “In places where a rucksack rests, for example, water can penetrate the fabric despite impregnation. Therefore, the membrane has its place in corresponding products.”

Otherwise, there could also be problems with continuous rain or sleet that stays on clothing. In addition, the water-repellent effect decreases over time, for example due to mechanical abrasion or washing.

So a lot has happened since Charles Macintosh’s invention 200 years ago. Incidentally, since 2007 the Mackintosh brand has belonged to the Japanese group Yagi Tsusho. For the high-price segment, they still have coats made in a factory in Lancashire, UK, using the classic production principle.

“Aha! Ten minutes of everyday knowledge” is WELT’s knowledge podcast. Every Tuesday and Thursday we answer everyday questions from the field of science. Subscribe to the podcast at Spotify, Apple Podcasts, deezer, Amazon Music or directly via RSS feed.