Let's talk about PU coatings

Let’s talk about PU coatings

Table of contents

PU coatings… Anybody who’s ever perused the intricate details of the production of outdoor clothing has probably stumbled upon this term at some point. But, have you ever asked yourself what the mysterious little abbreviation “PU” actually means? Or whether you actually need it? Could you do without it? Let’s find out!

Definition, properties and effect

Let’s begin by having a look in our trusty internet dictionary to see what polyurethane means. This will tell us that polyurethane – PU for short – denotes a a class of synthetic materials. This class of synthetic materials is in rigid foam, flexible foam, liquid form or casting resin. The famous industrial chemist called Otto Bayer discovered the polyaddition for the synthesis of polyurethanes in 1932.

Polyurethane foam insulation inside house walls
Rigid polyurethane foam insulation for houses

Pretty useful stuff, right? But, what about all this talk about polyurethane coatings on apparel? Well, as the term already suggests, a “PU coating” is a protective film made of polyurethane. Simple, right? When used in its liquid form, polyurethane can be transformed into a permanent waterproof treatment. And this is precisely where things get interesting for us outdoorsy folk.

In order to provide textiles with an additional layer of protection, a thin film of liquid PU is applied to the garment. The PU coating has extremely strong water-repellent characteristics and is even capable of making fabrics completely waterproof! Such a film can be applied once or multiple times. One coat is appropriately called single-coated, whilst multiple coatings are referred to as multicoated. Depending on the area of use, manufacturers treat either the entire surface of the garment or just single fibres. Besides waterproofing the garment, PU coatings also make the fabric more robust and more resistant to tears, kinks and abrasion. These coatings also happen to be very flexible and durable. Plus, thanks to modern manufacturing processes, it’s now even possible to make breathable PU fabric! Magical, right?

The upsides and downsides of polyurethane coatings

A real disadvantage is definitely the weight of a PU coating. A polyurethane coating may be nothing more than one (or multiple) layer(s) of plastic, but it does have some weight to it. In fact, polyurethane-coated fabrics tend to be heavier than those treated with DWR. So, if you an ultra-light garment is what you want, I’d steer clear of PU-coated apparel.

Two persons in outdoor clothing
PU coatings are primarily used for outdoor clothing

A polyurethane coating also has a certain amount of volume to it, so a polyurethane-coated jacket would be somewhat bulkier than a “normal” outdoor jacket as well. True, that may just be an aesthetic disadvantage, but for me, PU-coated textiles look so much heavier than those with a DWR treatment. Personally, I’d prefer to wear something lighter and less bulky. But that’s just me!

Polyurethane-coated textiles have had one major thing going against them: their lack of breathability. But we can breathe easily now that that’s no longer the case! Thanks to modern technology, PU-coated fabrics are highly breathable as well. One such modern technique is called a microporous coating. Basically, this is a PU coating that contains billions of tiny holes. These holes are so small that water vapour can escape to the outside, but moisture can’t get in. Voila! Breathability! Fortunately, these coatings are not as expensive as you would think and are now widely used for outdoor textiles.

Environmental impact and uses

Of course, there’s a lot to be said for PU coatings in terms of environmental sustainability as well. A PU coating is clearly the environmentally friendlier alternative to many DWR treatments. Admittedly, polyurethane is by no means the environmental angel hovering over the outdoor industry. Quite on the contrary! When it comes to the production and the disposal of polyurethane, it can get pretty problematic. But in comparison to a fluorocarbon DWR, PU is as innocent as a lamb. Fluorocarbons (perfluorocarbons or PFCs) are very harmful to the environment and can be harmful to our health as well. That’s why so many outdoor clothing companies steer clear of them. Also: When compared to PVC coated fabrics, which contain toxic plasticisers, PU definitely comes out ahead.

Areas of use

Waterproof jacket with PU coating.
PU-coated clothing are particularly waterproof

So, now that we know a bit more about polyurethane, the coatings themselves and the pros and cons of the polymer, we can move on to what a PU coated garment is best suited for. Nobody’s going to wear a heavy coated jacket for a trail run on a warm sunny day. Rainy and damp weather is where these garments are at their best. As a general rule, we can say the PU-coated garments are best for “normal” bad weather. If the fabric and seams are nice and sealed, even the craftiest of raindrops won’t be able to penetrate your garment.

Even though modern coating techniques have made it possible to manufacture breathable PU-coated fabrics, you shouldn’t wear them for highly aerobic activities in bad weather. Look for an alternative instead. Why? Well, for one thing, the breathable properties will never suffice for high-intensity physical activity. For another, the coated fabric will just weigh you down. For bad weather and when you need a particularly strong and abrasion-resistant garment, PU-coated fabrics are the way to go. Polyurethane-coated Cordura (a particularly strong polyamide fabric), for example, can withstand the sharpest of rock edges without any damage. Pretty neat, right?

Well, that’s about it for polyurethane-coated textiles. You’re all probably sick and tired of reading the word polyurethane, anyway! Still, I hope I was able to shed some light on the mysterious polymer that is PU!

If you have any questions, feel free to ask our experts in customer service. They are available during the week from 8 a.m. till 4 p.m. and can be reached by phone at 03 33 33 67058 or per e-mail.

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Alpinetrek-Expert Guest author

Alpinetrek-Expert Guest author

No comments yet

  1. Is there Latex in this product. As I’m extremely sensitive to it. And have had sevier allergic reaction.
    Thank you Tracy..

  2. Hi, when you say reproofing after washing , can a pu coated jacket be reproofed? If so, how please.! I have a berghous I desperately want to revitalise!! Many thanks

  3. Could I apply a new PU coating to an older rain jacket. For example. Montane Atomic DT. Where the inner lining has started to flake away? Would this work. As it’s different to tent flysheets or groundsheets.
    This is a common problem with older Jackets.
    I’m assuming the breathability would be greatly reduced though.
    Obviously the old lining would have to be completely removed first.
    Many thanks.

  4. I have old work flurestant waistcoat it still has works logo but I need to cover it,please could you advise me please,material of jacket states 100% polyester pu coated,thankyou.

  5. I have a linen jacket with a light PU coating. I’d like to get rid of the texture and stiffness of the coating. light machine wash? light machine dry?
    Plse email me at joan@joantucker.com

    Thanks very much

  6. Hey,
    I am looking to reproof my tent’s rainfly. I was told to remove the old PU coating from the internal facing side and apply a new layer. Can you recommend a PU products to use for reproofing?

  7. Hello Kristy,

    yes PU coating is washable, normally not more than 30 degrees, and please don´t use fabric softener. Important is the reproofing after the washing.

    Kind regards,


  8. Hello Tracy,

    unfortunately I don´t know which product you are referring to, if you let me know that, I´ll take a look at it.

    Kind regards,


  9. Hello Tom,

    yes you can rproof the coating after washing your jacket with Nikwax spray, which we donßt stock in our UK shop at the moment, I´m sorry.

    Kind regards,


  10. Hi Chris – in my opinion this isn’t a practical option unfortunately – it would effectively reduce the breathability to nil and be like wearing a plastic bag. In that situation I’d have to recommend replacing the jacket.

  11. Hello Paul,

    this means, that the fabric is bulit with three layers, so the membrane is especially robust.

    Kind regards,


  12. Hi Joan, I couldn’t really recommend it to be honest. It’s likely the effect wouldn’t be what you wanted and may well compromise the integrity of the material.

  13. Hi Kate,

    ‘Reproofing’ means that you treat a product so that the protective coating of the outer material is reactivated and it can fend off rain and dirt. To revive a product you should ‘proof’ it from time to time.

    Best regards,

  14. Hey,

    I would recommend using Tent & Gear Solarproof by Nikwax, which we don´t have in stock currently, sorry.

    Kind regards,


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