[This is the latest in a series of posts on Cloth that has now built into something very substantial: browse the others on the dedicated page here]

The use of synthetic fibres in cloth for tailoring is generally frowned upon by consumers, and with good reason.

Most of the time, synthetic fibres are included to save money – to try and replicate some of the aspects of good natural materials at a lower cost.

However, as with most things, it’s not always so simple.

There are different types of synthetics, sometimes used for very practical benefits, and they don’t necessarily make cloth cheaper. I’ll lay some of those out in this piece.

Overall, though, it’s still worth retaining that scepticism. Natural fibres have their own performance properties, and usually just require a little more care. If you can’t be bothered to give them that, then frankly there’s no point spending good money on clothing in the first place.

First, the types of fibre. There is huge variation here, but essentially these split into two big categories, usually called artificial and synthetic.

Artificial fibres originate in natural materials (either plant or animal, cellulosic or protein) and are then repurposed, usually with chemical treatments. Examples are Rayon, viscose (above), Cupro, acetate and triacetate.

Synthetic fibres do not use natural materials, but are made from synthesised polymers of small molecules (usually from petroleum).

The most common here are polyester, polyamide (Nylon, below), Lycra, Modal and Teflon. Some of these are brand names, some not, as indicated by the capitalisation.

Synthetics are easier to manipulate than artificial ones, and are therefore more commonly used in sports or active clothing, where you might need a specific combination of breathability, water resistance and stretch, for example.

The fibre itself is also often made with properties such as being stainproof or stretchy, whereas natural and artificial fibres achieve this through the weave or (more commonly) a finish on top. It’s usually not in the yarn.

Synthetics are also generally tougher than natural or artificial fibres, but suffer in being more sensitive to heat and not very comfortable or allergy-friendly.

Which is why people are more likely to wear a cotton T-shirt (the most comfortable against the skin), wool knitwear (warm and temperature-regulating) and synthetic outerwear (lightest, toughest, most water-resistant).

Artificial fibres like viscose have some of the benefits of natural ones, such as being biodegradable, but are also more energy-intensive to produce than natural fibres.

So they are certainly better in some ways than synthetics, but also have their disadvantages.

It’s at this point that it’s worth highlighting the natural performance aspects of natural fibres like wool.

Wool is hypoallergenic, flame-resistant and odour-resistant. But its most important feature is probably that it can absorb so much water (more than 30% of its weight) before it feels damp or cold.

This applies to moisture coming from the outside (rain) and inside (sweat). So it rarely feels cold and is a natural thermoregulator.

There are then natural performance elements that come through how wool is spun or woven. A plain weave is more breathable than a satin weave; high-twist yarn increases elasticity and wrinkle recovery; a milled or brushed finish traps air and retains heat.

If you want something to be tougher, just use a coarser yarn. Tweed is very resistant to abrasion or tearing; its hairy surface creates water-resistance; and it has all the other advantages of wool above.

Plus it feels nicer. I put on a synthetic rain jacket for the first time in months the other day (to go camping). It has minimal stretch, it doesn’t move with the body, and it’s really loud. It crinkles constantly, like wearing a bin bag.

In that situation, I needed it for a very specific purpose: staying in the rain for a long time – as I put up a tent, for example – and drying very quickly afterwards. Tweed would stay damp for too long.

But at home I would always wear a wool or cotton coat in the rain, perhaps in a Ventile weave or with a light wax or other coating, because it’s so much nicer to wear.

There are treatments for natural materials, of course, as we covered in more detail in the equivalent of this post for shirt fabrics.

These can make wool or cotton more resistant to water, stains or bacteria, by soaking it in a chemical bath.

But those treatments eventually wash out (more an issue with shirts than suits) and usually reduce the nice ‘hand’, the feel, of the material.

The only one that works very well is ‘real’ natural stretch: where fabric is woven larger than required, then washed in soap and water to shrink it down.

I know many people dislike synthetic fibres because they don’t have the heritage or craft of natural ones.

Synthetics are made in a lab, where natural fibres come from animals bred in the field, then shorn and woven in traditional mills – and sold by companies that might have been doing the same thing for centuries.

Personally, I’m not as emotional about it. But it is true that most synthetics only aim to increase performance, whereas natural ones tend to aim for feel and for beauty.

A cashmere overcoat is made to be a beautiful object: lustrous to look at and luxurious to wear.

If it’s raining, don’t complain that the coat isn’t waterproof. Just carry an umbrella.

As a final word, I’d say that as a general rule you should only use cloth with synthetic fibres when you want it for a particular purpose.

So some lightweight, open-weave slubby linens have synthetics added, to give the cloth body and sharpness. You sacrifice a little of the feel, but you know what for.

Be sceptical of a navy overcoat that has 20% polyester in it, when it would be perfectly practical in 100% wool. You’re not gaining much, and chances are that one reason for including the synthetic was to reduce the price.

Thanks, as ever, to Luca Driusso and others for their help with this article.