DWR, WP Coating vs. WP Laminate

[EndoftheTrail]

A while ago, in response to my questions re. wp/b coating, laminate/membrane, I received the following response from MontBell. This may be of interest to some:

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Hi Ben,

Thanks for contacting us with your questions about rainwear, hopefully I can sort this out for you.

We're basically talking about three different things here:

1) DWR treatments
2) Waterproof/ Breathable coatings
3) W/B laminates

1) Durable Water Repellent (DWR) treatments are applied to the exterior surface of most (all MontBell) rainwear. When you notice water beading off your jacket, you are seeing the DWR at work. The quality of a water repellent finish is determined by measuring the percentage of the original water resistance after a specific number of washings, for example 20/50 means that a treatment maintains 20% of it's original water resistance after 50 washings. MontBell uses Polkatex DWR on all rainwear, and it has a rating of 90% of original water resistance after 100 washings (90/100). This is about as good as it gets. Washing, while perhaps a poor test, is the standard way of simulating real-life wear and tear in a lab setting. We don't really intend that you'll have washed your jacket 100 times, it's more for the purposes of comparison. DWR treatments will degrade over time due to becoming dirty, abrasion, and contamination, but can be renewed through washing and drying, as well as re-treatment.

2) Waterproof/ Breathable (W/B) coatings are almost always polyurethane based and are generally used on less expensive rain wear. Coatings are generally less breathable than laminates, and of less consistent quality due to variations in the thickness. Coatings, as the name implies, are basically smeared onto a finished fabric and then cured. Just like smearing cream cheese on a bagel, it's hard to get the thickness truly consistent and accurate. As a result, the coating often needs to be made thicker to ensure that even the thin spots are sufficiently water resistant. Coatings do not degrade with washing or wear the same way that DWR's do, but are susceptible to long term wear. Furthermore, water is actually a solvent of polyurethane, so the material ultimately becomes softer and more susceptible to wear in exactly the situations for which it was designed. This weakness is really more for the purposes of argument and comparison, in everyday life, a coating can still deliver many years of excellent performance. Hydrobreeze is the only coated W/B material in MontBell's line right now. Everything else is a laminate.

3) W/B laminates are either polyurethane (PU) based or teflon (PTFE, ePTFE) based. To make them, the PU or teflon is cast out over an extremely smooth surface (far smoother than a finished fabric) and then glued (laminated) to the surface fabric. Because the thickness is more uniform, it can be overall thinner, allowing for more breathability for the same water resistance than a coated material. Some laminates will also have an additional (usually very thin) coating. Gore-Tex is one such material, where the ePTFE laminate has a very thin PU coating to prevent contamination from body oils. Some PU laminates also have a PU coating. Instead of washing, the durability of a coatings or laminate is measured through a 'wet flex' test. As the name implies, the fabric is wetted and a machine basically flexes of folds the fabric for a set period of time. The fabric is periodically tested for water resistance until it reaches a failure point. This is where the primary difference lies between PU and ePTFE. ePTFE laminates last several times longer in this test than even the highest quality PU laminates. Again, these weaknesses are more for the purposes of comparison, and all MontBell products should deliver many years of trouble free service. The durability factor is, for me, the primary reason that one would choose a Gore-Tex (ePTFE) product over any of the PU products that we or anyone else makes. Furthermore, all of the Gore-Tex XCR jackets in our line, as well as the Peak Shell, use a 3 layer laminate, meaning the fabric is constructed from a layer of surface fabric (usually nylon) which is laminated to the waterproof/ breathable "laminate" which is then laminated to a lining (usually polyester tricot). These constructions offer extra durability, abrasion resistance, overall strength, and performance over "2-layer" constructions. Again, these strengths and weaknesses are for the purposes of comparison, and are not meant to indicate that one product is a 'bad' product. All the materials that MontBell uses are of the highest quality and the products they're made from should deliver long term, high quality service. Material selection comes down to fulfilling certain sets of requirements and priorities.

While a bit long-winded, I hope this is good information for you.

[EndoftheTrail]

Here's an excerpt of another email from MontBell in response to my question regarding their air-permeable Breeze Dry Tec laminate versus the also air permeable eVENT laminate and the various Gore Tex type laminates.

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Hi Ben,

The Peak Shell uses a MontBell proprietary PU based laminate that we call Breeze Dry Tec. This is a fairly high tech fabric, in that it is air permeable, which most W/B's are not. For this reason, Breeze Dry Tec is more breathable than Gore-Tex XCR (Gore's most breathable product).

Very few materials are Teflon based. For the most part, it's just Gore-tex and Event. These are both ePTFE (expanded PolyTetraFluoroEthelyne). I think there are a couple other small players using some other PTFE (not expanded), but I'm not really sure. The primary difference between Gore and Event is that Gore-Tex applies a very thin polyurethane coating to the interior of the laminate to prevent contamination from your body fluids and oils. This reduces the breathability. Event claims to have figured out a way to prevent contamination without the coating, making the material air permeable improving the breathability. Gore claims it is not as reliable, they believe that it will still contaminate.

Most PU laminates use a similar PU non-porous coating as Gore-tex because the micropores in the PU are inconsistently sized and water resistance can become an issue. With Breeze Dry Tec, we have figured a way to skip the extra coating through use of a very high quality PU with extremely consistent pore size. The result is similar water resistance as other non-Gore laminates on the market, and a dramatic increase in breathability.

[Richard Nisley]

Ben-Thank you for some additional information of value that wasn't covered in the BPL related articles. I tried to find an independent source for Polkatex DWR but, I didn't have any luck.

[EndoftheTrail]

Richard:

You're welcome! While the above was from a MontBell wholesale manager who had since moved on — I found his explanations easy to read and also very logical.

I would trust his descriptions about the effectiveness and longevity of MontBell's Polkatex DWR. Goofy name though.

[Eric Carlsen]

This is a side topic but what really amazes me about this thread is the sheer amount of time the MontBell rep put into his explanation. That's some good customer service. Gives me warm fuzzies about the super stretch down bag I've got coming.

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