By The Numbers Quickie: Meet my Shakedry Replacement-The Finetrack Photon WPB

[Stephen Seeber]

There has been a lot of gloom and doom lately on Backpackinglight.com about the dearth of lightweight, high MVTR jackets that can function as both a windshirt and a rain garment.

Readers of BPL are undoubtedly familiar with the Finetrack Elemental layer. This is a very light, highly porous, hydrophobic polyester base layer designed to permit easy transfer of water vapor from the skin to succeeding clothing layers.  I have been wearing the Elemental Layer tops and bottoms for many years and have written about them in prior articles.

I came across the Photon jacket while browsing Finetrack’s website for new and interesting products. The Photon jacket is fully featured with reasonable weight and packability. The jacket features a membrane I was not familiar with. I asked them to send me one for MVTR testing. Below, I will describe what I have learned so far about the jacket’s robust feature set.

Jacket Weight: The jacket weighs 11.65 ounces in a Japanese size Extra Large. I think this is equivalent to a US Large. I am 5’10” tall and 175 pounds.  The jacket offers me plenty of room for layering.  I think the robust feature set included in this jacket makes the weight very reasonable.  It is about 3 ounces heavier than my Montbell Shakedry jacket.

Jacket fabric: The face fabric is a 15D Nylon Ripstop. The liner fabric is a 20D Polyester Knit.

Figure 1 shows the knit liner fabric and woven face fabric.

As can be seen from the backlit images, both fabrics are highly porous, particularly the liner.  The fabrics provide durable protection for the membrane while adding minimal resistance to vapor transfer through the jacket shell.

Wind and water resistance, coupled with high water vapor transfer, is provided by the polycarbonate-based polyurethane microporous film (PC/PU). I am not aware of any other products that utilize this type of membrane. According to Finetrack, the PC/PU membrane is significantly more resistant to hydrolysis than conventional PU membranes. Hydrolysis occurs when water is absorbed into a PU membrane, leading to the delamination of the membrane from the face and/or liner fabrics.

I measured the MVTR of this fabric to be 3,760 grams/square meter/24 hours. I have measured one electrospun fabric that had slightly higher MVTR than the Photon jacket. So, this is the second-best waterproof breathable membrane I have tested for water vapor transfer. It may provide the highest MVTR in a jacket that can be purchased for use. The MVTR of the Photon jacket is 11% higher than that of my Montbell Shakedry jackets, which are far less durable than the Photon jacket.

Another feature of this waterproof, breathable shell is that its fabric has stretch! Finetrack lists the stretch as 107% vertical and 117% horizontal. This stretch ensures a more comfortable and less restrictive fit.

Zippers: This jacket introduces a new product from YKK called Aquaguard Tightened. This new zipper offers a tighter front closure than a conventional Aquaguard zipper, eliminating the need for a front or rear flap to achieve adequate water resistance.

This is illustrated in Figure 2.

The left panel illustrates the tension applied to the zipper opening tapes when the zipper is closed. The center panel shows the zipper subject to backlighting.  We can see light coming through the bottom metal zipper tabs, but no light comes through the zipper seal. The right panel shows a backlit conventional Aquaguard zipper on a Montbell Shakedry jacket. Abundant light is leaking through the zipper seal.  The Montbell Shakedry jacket has a flap behind the zipper to keep water out.  The Photon eliminates the fabric flap, relying on the tight seals of the new zipper design.

The jacket features four Aquaguard Tightened zippers: the front zipper, two ventilation zippers on the sides of the torso, and an external pocket. Finetrack has developed a ventilation system that aligns airflow across multiple layers of clothing. This system is called Linkvent. The zippered torso vents on the Photon serve as the final access point to the external environment.

Hood: The hood is helmet-compatible and features a brim. You can adjust the hood’s volume and front opening using a single adjuster located at the rear. The adjustment system effectively reduces the large hood volume to create a snug fit around the head and face.

Cuff and Hem Closures: The sleeve cuffs feature hook-and-loop closures, providing maximum control over sleeve ventilation while keeping driving rain and snow out. The jacket hem is controlled by a shock cord that is adjusted with a single spring clip.

DWR treatment: The jacket has C6 DWR applied to the face and liner fabrics.  Finetrack indicates that their fabrics are compatible with Grainger’s and Nikwax DWR products when reproofing is needed.

Pockets: The Photon features both exterior and interior zipped chest pockets. These pockets are spacious enough to accommodate my iPhone 16 Pro along with its protective case.

Sizing: The Photon is available in Japanese sizes.  The US equivalents are XS, S, M, L.

Pricing and purchasing.  The jacket may be purchased from the Finetrack website for $411. Delivery to the US by DHL is shockingly fast.

Field Experience: I have had limited use of this jacket, but have experienced high winds above treeline and a couple of short but intense rain squalls. The jacket has kept me warm and dry. The fit is comfortable with room for additional layers. Thanks to the Photon, I have put away my remaining Shakedry jackets, which are well-worn and no longer reliably waterproof. I expect this jacket will successfully replace the older jackets for a wide range of activities.

[Bill Budney]

Sounds like an interesting jacket. Thanks for the report!

• Does it have measurable air permeability?
• Which electrospun scored higher in MVTR?
• > “compatible with Grainger’s and Nikwax” <– Is that a credible claim (with reasonable effectiveness)? I thought that we needed to use FC on FC or wax on wax for maximum adhesion?
• > “Finetrack has developed a ventilation system that aligns airflow across multiple layers of clothing”. <– OK, so what is this fancy new ventilation system? All I see are torso zips closer to the center than traditional pit zips. I agree that is better placement for them (ventilation may not  be cut off by a pack’s shoulder straps). Is there any more to it than that?

I’m looking forward to hearing more about your field experience.

[Stephen Seeber]

Hi Bill:

• I calculated .29 CFM/Ft2. This is through curve fitting, since my instrument does not officially measure below 1 CFM/Ft2. In my opinion, air permeability for WPB is irrelevant.  It is too low to have a tangible impact on user comfort under most usage conditions.
• The Neoshell fabric was style 6770, which achieved an MVTR of 3893.  It was an exceptionally lightweight fabric — around 100 gsm. HH was 9829, and air permeability was 1.19.  I am pretty sure you won’t find a commercial product made from that fabric. Its excellent MVTR performance was likely due to its very light face and liner fabrics.
• I specifically asked Finetrack what could be used for reproofing.  They provided the information I included.  I have not tried either product on the jacket they provided, so I have no further information.
• If you go here on their website, you can see a fuller explanation.  They have a five-layer clothing system.  The three outer layers will have these vents in the same positions. I have not tried this system, but I could see how it might be a sensible approach in the right conditions.

 

 

 

 

[Jerry Adams]

There’s nylon on the outside and polyester on the inside, both treated with DWR C6?

And a membrane in between?

That must be several ounces per square yard.  I wonder if you can buy just the fabric.

Interesting product

Finetrack Elemental layer must be just a thin polyester fabric?  I’ve been experimenting a bit with a hydrophobic base layer.  I noticed it doesn’t get wet when it’s raining, even if my rain jacket isn’t perfectly keeping water out.  I wonder if there is available any thin hydrophobic polyester fabric for MYOG.

[Bill Budney]

That’s helpful about the NeoShell 6770. I see that it is the lightest 3 layer NeoShell or Power Shield Pro that Discovery Fabrics sells, so probably a good target for MYOG.

I know that we disagree about the value of air permeability in WPBs. I’m pretty sure that it matters, but maybe not in the obvious way. It’s not going to produce a ton of cooling in the way that a good windshirt does, but the fact that it allows SOME cooling makes it immediately superior (in comfort) to membranes that have none. I notice it when comparing ShakeDry to AscentShell (electrospun), which have very similar scores on your MVTR test.

It will be interesting to see whether you have similar experience with your Photon.

 

[Jerry Adams]

decoder ring for neoshell

https://cdn.shopify.com/s/files/1/0076/7318/4341/files/Neoshells_at_a_Glance_October_2022.pdf?v=1666200646

I got one of the no stretch neoshells and that made a really good rain jacket.  Pretty much stays dry

[Stephen Seeber]

Hi Jerry, regarding your comments on the fabric construction. The Photon construction is typical for a three-layer WPB.  Some weight can be saved with a 2.5 or 2-layer construction, but the three-layer construction will provide better protection for the membrane and likely offer a better feel against bare skin.  I think the 15 denier nylon face fabric is an excellent trade-off between durability, weight, and MVTR.  It is possible to produce a lighter 3-layer membrane using 7-denier fabric, such as the Zpacks Vertice or EE Visp. However, you end up with a very fragile shell, a urethane membrane with substantially lower MVTR and an increased chance of failure due to hydrolysis.  Also, the 7 Denier 3 layer fabrics must use a restrained HH test. This places a metal grid over the test sample during the test. In my experience, a non-restrained test will cause the seven-denier fabric to rupture.  The HH result is not comparable to the results of a restrained test.

Regarding hydrophobic polyester.  It may exist, but I have gone to a lot of trouble to find and purchase fabrics that do not specifically claim to wick.  I have yet to find one that is actually hydrophobic.  You can make a wicking polyester hydrophobic by treating it with Nikwax.  I have found this to be very successful, but I have not put any shirts into regular use so I don’t know how often retreatment would be necessary.  Your other alternative would be to purchase Helly Hansen Lifa, which is Polypro.

[Woubeir (from Europe)]

I notice it when comparing ShakeDry to AscentShell (electrospun), which have very similar scores on your MVTR test.

And what exactly do you notice?

[Jerry Adams]

Thanks Stephen

I’ve been looking for a hydrophobuc polyester too.

Of course, polypropylene is hydrophobic.  I made a shirt with that.  Maybe, that fabric is uncomfortable against the skin.

When the WPB fails, the inside of the membrane gets wet.  If the inner fabric is hydrophobic, then the water stays on the inside surface of the WPB, and doesn’t get any clothing inside wet.

[Bill Budney]

what exactly do you notice?

The electrospuns are slightly more comfortable while active. Not a lot, to be fair, but enough to persuade me that there is more to WPB comfort than any single lab measurement. Enough that I choose an electrospun when I know that the weather will be light.

I get a little condensation inside of ShakeDry while working that I don’t notice in AscentShell. They have nearly identical MVTR, so what is the difference? AscentShell is a hydrophilic membrane with very small air permeability, which ShakeDry is a hydrophobic membrane with essentially none. Polartec claims that the small amount of air permeability matters. My experience is consistent with that.

OTOH, in driving rain, I get a small amount of moisture inside the AscentShell that I don’t notice inside of ShakeDry or Outdry. I used to think it was condensation encouraged by the wet out face fabric, but there may also be a small amount of reverse-wicking possible in electrospuns. This effect may increase due to age and/or use.

Another observation is that my EE Visp is more comfortable in light weather than ShakeDry, even though the ShakeDry has superior MVTR.

There are confounding factors. My Visp has pit zips, my ShakeDry does not. Both my AscentShell and Visp fit better than my ShakeDry, which is narrow in the upper arms, inhibiting air flow.

These effects are subtle and we don’t have any way to measure them, which is why we haven’t discussed them (although I report them to Stephen as I notice them). I only say it here because Stephen brought it up. Otherwise, this is in the “we need more information and further field testing before we can come to confident conclusions” category.

 

[Stephen Seeber]

Hi Woubier. I have had lots of use from Shakedry over the years and a few weeks of summer use for the Photon jacket.  In terms of MVTR, their test performance is similar, and I doubt I can perceive a difference in similar circumstances. I expect that the durability of the Photon will far exceed that of Shakedry.  I had pit zips in my Shakedry jackets (aftermarket).  I expect that the layers on my arms in the Photon will retain more moisture than the Shakedry due to the differences between pit zips and torso zips.  I was happy with Shakedry’s performance, but not Shakedry’s durability. I expect I will be happy with Photon’s performance and durability.

[Woubeir (from Europe)]

Stephen, it would be interesting to know how the DWR is performing in a long rain shower.

BTW, is there here a  study on how DWR influences the MVTR?

[Jerry Adams]

are there any studies about anything about DWR?

[Stephen Seeber]

Hi Woubier and Jerry: I have two studies done by Philip Wayne Gibson with the Natick Soldier Research, Development, and Engineering.  Gibson, now retired, was a highly influential and prolific researcher in the field of military clothing.

Here is the conclusion from his 2005 study.  This study was done using C8 treatments, so results may vary for present day treatments.

Two of the water-repellent treatments had good durability to laundering. One treatment
had very poor durability, and lost all its water-repellent properties after 20 laundering
cycles. The Quarpel-treated control fabric performed better than any of the
experimental treatments. None of the water-repellent treatments significantly affected
the breathability, air flow resistance, or pore size of the BDU fabric.

It was found that the standard Battle Dress Uniform (BDU) fabric can be modified with
very effective water-repellent treatments. Soldiers’ duty and combat uniforms can be
made water-resistant and retain the same air permeability and “breathability” properties
as the untreated wicking fabric. Several questions arose as a result of this work. What
are the physiological implications of changing the BDU fabric from a wicking fabric to a
non-wicking fabric? Will the fabric still be comfortable when a soldier is sweating
heavily? Will liquid sweat now remain on the skin underneath the fabric, and is this bad
or good?
Following a separate field trial using combat uniforms with and without a DWR
treatment, it was found that these treatments decreased the comfort of the uniform in
hot environments. The differences between the comfort of the Control uniform and
those treated with the DWR treatments are probably not due to intrinsic differences in
the air permeability or the water vapor diffusion resistance (breathability) of the fabric. It
is more likely that the non-wicking behavior of the fabric was responsible for perceived
comfort differences, per comments from the field trial, and by analysis of
wicking/comfort properties contained in this report.
Some of the DWR treatments are available as coatings on just one side of the fabric.
The outer layer of the fabric can be made water-repellent, while the inner surface
retains its wicking characteristics. Based on comments from the field trial, and modeling
results, such asymmetric treatments would improve the comfort of DWR treatments on
military duty uniforms as compared to water-repellency on both sides of the fabric.

In this study, there is a statement that improper application of DWR can fill the fabric pores and impact fabric performance, but no examples are provided and this did not occur in any of his publications.

We don’t know if the comfort degradation found for the DWR treatment in the uniform garments under high effort, high humidity and high temperature conditions may be mitigated for our use purposes by choosing garment with far higher permeability and adding layers, such as Brynje that encourage evaporation from the skin.

One article can be downloaded here.  Another can be found here.

This is an area of research that is of interest to all of us and one I intend to pursue.  I have one relevant article ready for publication, but when this happens is out of my control. So, stay tuned.

 

[Jerry Adams]

Thanks, that will be interesting

[Woubeir (from Europe)]

Absolutely.

Because that was according to me the most important feature of Shakedry: the  PBS.

Here it would be something like this as a question: how is the MVTR affected on a garment with a classical construction vs a garment with a PBS and that after wet-out (of the classical garment as is supposed that a garment with a PBS doesn’t wet-out)?

[Woubeir (from Europe)]

Hi Bill,

AscentShell is a hydrophilic membrane with very small air permeability, which ShakeDry is a hydrophobic membrane with essentially none

do you have an AP-value for AscentShell because both are AP?

 

[Bill Budney]

Hi, Woubeir. The air permeability of (2024) AscentShell is small. I generally assume between 0.5 and 1.5 CFM.

I don’t have any reason to think that greater air permeability matters in WPB garments. I’m pretty sure that “a little” is more comfortable than “none”, but we don’t have the resolution of test gear required to differentiate between them.

The tradeoff for the greater comfort is possibly less than perfect water resistance. It’s pretty clear that hydrostatic head doesn’t tell us the entire story there. The Motive AscentShell tested (or was estimated) at > 10,000 mm of H20, which sounds plenty waterproof. But if the pores stretch after repeated use and stuffing, and if the hydrophilic membrane wicks a little, then a small amount of water may ingress anyway (in heavy rain).

In heavy rain, my AscentShell feels soggy inside. My Outdry remains drier. But the AscentShell is more comfortable in light weather.

Tradeoffs: different membranes perform differently. Electrospun is great for light to moderate weather, while Outdry and Gore-Tex may be more waterproof in heavy weather.

What is “PBS”?

[Woubeir (from Europe)]

PBS = Permanent Beading Surface (so no separate application of a DWR needed)

Shakedry may have an AP ranging from 0,3 to 0,9 so maybe the difference you feel is not because of the AP but just another reason (still unknown to us).

[jscott]

I love it when scientists and their acolytes use abbreviations about technical materials only to conclude, “AP ranging from 0,3 to 0,9 so maybe the difference you feel is not because of the AP but just another reason (still unknown to us).”

I’m old and don’t have time to wait for the MTV to meet up with PBS  to bring me the hip hop News Hour while I’m wearing my leaky jacket in frigid temps.

“another reason still unknown to us” could be inscribed on every one of our tombstones.

 

[Jerry Adams]

That’s what I was thinking, public broadcasting system

Is polypropylene a permanent beading surface?

Maybe they could make the outer layers polypropylene

[Stephen Seeber]

Jerry: Check this out.

[Woubeir (from Europe)]

Is polypropylene a permanent beading surface?

No. The surface energy is too high with 30.

You need a surface energy of 20 or so,

[Jerry Adams]

Any idea how that polypropylene jacket would work in the rain Stephen?

I looked at https://www.tstar.com/blog/bid/33845/surface-energy-of-plastics

Fluorinated plastics are 20 but they’re unhealthful.  Rubber and Polydimethyl siloxane (which I think is silicone) are good but you can’t make clothes out of them..  Polyethylene and polypropylene are the best available.

In those links Stephen posted, they said DWR can wash out after laundering.  What about the DWR getting worse after exposure to water?  It seems like some DWR beads up initially, but after an hour in the rain it quits beading up, it wets out.  Other DWR continues to bead up after a long exposure to the rain.  Am I just imagining this?  Is this something you can test?

Polypropylene seems to maintain beading indefinitely.

Another thing that happens is I had a DWR jacket that wetted out easily, so I washed it, and applied DWR treatment and the DWR performed much better.  I’ve read that the DWR can get dirty over time which reduces effectiveness.

[Woubeir (from Europe)]

Jerry, what do you mean with ‘other DWR’?

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