For decades, the waterproof outdoor clothing market has been dominated by one name: Gore-Tex. For many walkers, climbers and mountaineers, the Gore-Tex label became almost synonymous with waterproof clothing itself. Pertex, eVent, Dermizax and manufacturers’ proprietary membranes occupied different positions in the market, but Gore-Tex remained the benchmark against which they were judged.
That comparison is becoming considerably more complicated.
The outdoor industry is undergoing one of the largest technological changes since waterproof-breathable membranes became commonplace: the progressive removal of fluorinated chemicals, particularly PFAS, from membranes and durable water-repellent treatments.
The result is a new generation of waterproof clothing that can retain extremely high laboratory waterproofness while behaving noticeably differently from older garments in prolonged rain.
To understand why, it is necessary to separate three things that are frequently confused: waterproofness, breathability and water repellency.
What Does “Waterproof” Actually Mean?
Waterproof fabrics are commonly compared using hydrostatic head (HH).
The test measures the pressure required for water to penetrate a fabric and expresses the result as the height of a theoretical column of water in millimetres.
A fabric rated to 20,000 mm HH can therefore resist approximately the pressure generated by a 20-metre column of water.
In practical outdoor clothing terms:
| Hydrostatic Head | Practical Interpretation |
| 5,000 mm | Basic rain protection |
| 10,000 mm | Waterproof for general outdoor use |
| 15,000–20,000 mm | Serious hillwalking and mountain use |
| 20,000–30,000 mm | Technical mountain protection |
| 30,000 mm+ | Extremely high resistance to water pressure |
The importance of very high hydrostatic head becomes clearer when pressure is applied to wet fabric.
Rain falling onto a jacket is only part of the problem. Rucksack shoulder straps compress saturated fabric against the body. Kneeling places considerable pressure on waterproof trousers. Sitting on wet ground produces another concentrated pressure point.
Consequently, the difference between 10,000 and 20,000 mm HH can matter considerably more in mountain clothing than it initially appears.
Modern Gore-Tex waterproof laminates remain particularly impressive in this respect, with Gore specifying waterproof performance exceeding approximately 28,000 mm hydrostatic head.
Many Pertex Shield constructions used in technical outdoor clothing sit around the 20,000 mm level, although the exact specification depends upon the particular laminate selected by the garment manufacturer.
Both figures represent genuinely waterproof fabrics. Gore’s higher figure principally provides additional resistance and margin under prolonged exposure and pressure.
Breathability Is More Complicated
The second number commonly used to sell waterproof clothing is breathability.
Unfortunately, it is considerably less straightforward.
One common measurement is MVTR — Moisture Vapour Transmission Rate.
It is normally expressed as:
g/m²/24 hours
A fabric rated at 20,000 g/m²/24h theoretically allows 20,000 grams of water vapour to pass through one square metre of fabric during 24 hours under the specified test conditions.
Higher numbers indicate greater moisture transmission.
Another measurement is RET — Resistance to Evaporative Heat Transfer.
Here the scale works in the opposite direction:
the lower the RET, the more breathable the fabric.
This immediately creates problems for consumers attempting to compare waterproof jackets.
More importantly, different laboratories and manufacturers can use different test procedures. Two fabrics both advertised with MVTR figures cannot automatically be assumed to have been tested under identical conditions.
A claimed 30,000 MVTR fabric is therefore not necessarily twice as breathable in the mountains as one claiming 15,000.
Gore-Tex and Pertex Are Not Direct Equivalents
There is another common misunderstanding.
Gore-Tex is a waterproof membrane technology and laminate system. Pertex is a textile technology company producing several different fabric systems.
Consequently, asking whether “Pertex is better than Gore-Tex” is rather like asking whether one entire range of engines is better than a particular engine design.
Pertex Shield includes different constructions, including two-layer, 2.5-layer and three-layer fabrics, with different weights, face fabrics and membrane technologies.
A current technical Pertex Shield garment might, for example, provide approximately:
20,000 mm hydrostatic head
20,000 g/m²/24h MVTR
That is already substantial waterproof-breathable performance.
Pertex Shield Air takes a somewhat different approach, concentrating heavily on air permeability and moisture movement during high-output activity.
This distinction becomes important when climbing quickly uphill.
The Gore-Tex Advantage
Traditional Gore-Tex developed its reputation partly because expanded PTFE — ePTFE — could create an extraordinarily effective waterproof-breathable membrane.
The microscopic structure contained pores sufficiently small to prevent liquid water penetrating while allowing water vapour to escape.
But Gore-Tex was never simply a membrane.
The complete system incorporated:
- face fabrics;
- membrane technology;
- backing materials;
- seam-taping requirements;
- garment construction standards;
- extensive testing;
- durable water-repellent treatments.
That complete-system approach remains one of Gore’s major strengths.
Modern Gore-Tex technology, however, is changing.
Gore has introduced expanded polyethylene — ePE — membranes, substantially reducing the environmental impact associated with the fluorinated chemistry historically used within waterproof clothing.
The new membrane can be thinner and lighter while retaining extremely high waterproof performance.
This sounds like an uncomplicated technological improvement.
In reality, removing fluorinated chemistry has created another problem.
The PFAS Question
PFAS — per- and polyfluoroalkyl substances — became extraordinarily useful industrial chemicals partly because of their remarkable resistance to water, oils and chemical degradation.
Those same properties created their environmental problem.
Many PFAS compounds persist for extremely long periods and have consequently become known as “forever chemicals.”
Outdoor clothing manufacturers have therefore been progressively eliminating intentionally added PFAS from waterproof membranes and, importantly, from DWR treatments.
DWR means Durable Water Repellent.
And this is where much of the consumer confusion begins.
Waterproofing and Water Repellency Are Not the Same Thing
A waterproof jacket normally contains several layers.
In a simplified three-layer shell:
Face fabric
↓
Waterproof-breathable membrane
↓
Protective inner layer
The membrane provides the fundamental waterproof barrier.
The DWR treatment is applied to the outer face fabric.
Its job is to make rain bead and roll away rather than allowing the textile to absorb water.
Older fluorinated DWR treatments were extraordinarily effective at doing this.
They also resisted oils and contamination particularly well.
Modern non-fluorinated treatments have improved enormously, but they generally require more careful maintenance.
This creates a strange situation.
A modern jacket can possess an exceptionally waterproof membrane while appearing to perform worse in rain than an older jacket.
The Problem of “Wetting Out”
When DWR is functioning correctly, rain behaves roughly like this:
Rain → droplets bead → droplets roll from garment → face remains relatively dry
When the DWR deteriorates:
Rain → face fabric absorbs water → textile becomes saturated → garment wets out
Crucially, this does not necessarily mean that water has penetrated the waterproof membrane.
The jacket may remain technically waterproof.
But something important happens to comfort.
A saturated face fabric severely compromises the garment’s ability to move moisture effectively.
The wearer is simultaneously producing heat and sweat inside the jacket.
Moisture transport decreases.
Condensation increases.
The inner surface becomes clammy.
The wearer feels wet.
The understandable conclusion is:
“My waterproof is leaking.”
In many cases it isn’t.
The waterproof membrane is still functioning.
The outer fabric has simply wetted out.
Why an Old Jacket Can Sometimes Appear Better
This produces one of the more interesting consequences of the PFAS transition.
A ten- or fifteen-year-old premium waterproof may sometimes appear to shed rain more impressively than a much newer jacket.
That does not necessarily mean its membrane is technologically superior.
Its fluorinated DWR chemistry may simply have been exceptionally persistent.
The comparison can therefore become:
Older fluorinated system
Excellent water beading
Excellent oil resistance
Slow contamination
Long-lasting surface repellency
Relatively forgiving maintenance
Modern PFAS-free system
Excellent membrane waterproofness
Reduced environmental persistence
Potentially lighter construction
Good initial water repellency
Greater sensitivity to contamination
More frequent maintenance required
The environmental improvement is substantial.
But the responsibility placed upon the owner has increased.
Washing a Waterproof Is Now Part of Its Performance
There remains an unfortunate belief among some outdoor users that washing waterproof clothing damages it.
The opposite can increasingly be true.
Body oils, sweat, dirt and contaminants accumulate in the face fabric.
These contaminants interfere with DWR performance.
Modern waterproof clothing therefore needs appropriate cleaning.
After washing, heat treatment — where permitted by the garment manufacturer — can help reactivate the DWR.
Eventually the original treatment becomes exhausted and a suitable replacement water-repellent treatment needs to be applied.
For modern PFAS-free garments, maintenance should increasingly be regarded as part of the waterproof system rather than an optional cosmetic procedure.
Where Does Pertex Fit?
Pertex presents an interesting alternative because its technologies can be optimised differently.
A conventional technical Pertex Shield fabric offering around 20,000 mm HH and 20,000 MVTR already provides sufficient waterproof performance for extremely demanding conditions.
But technologies such as Pertex Shield Air concentrate on another problem: moving moisture during intense exercise.
This introduces the concept of air permeability.
Conventional waterproof-breathable membranes predominantly rely upon moisture vapour passing through the membrane.
Highly air-permeable membranes permit a small degree of actual airflow.
That can increase comfort dramatically during high-output activity.
Imagine two mountaineers wearing waterproof shells.
One is standing at a belay in freezing rain.
The other is climbing rapidly uphill carrying a pack.
The first primarily needs protection.
The second is producing enormous quantities of heat and moisture.
The ideal waterproof for one is therefore not necessarily the ideal waterproof for the other.
Other Important Alternatives
Gore-Tex and Pertex are far from alone.
eVent developed a strong reputation around highly breathable “direct venting” membrane technology.
Dermizax, developed by Toray, uses hydrophilic membrane technology and has been widely used in technical ski and mountain clothing.
The North Face Futurelight uses a nanospun membrane structure designed to combine waterproofness with unusually high air permeability.
Patagonia H₂No is slightly different because H₂No is effectively a performance standard rather than one single membrane. Fabrics must meet Patagonia’s requirements for waterproofness, breathability and durability.
Other manufacturers including Rab, Mountain Equipment, Berghaus and numerous European brands increasingly employ their own proprietary waterproof technologies.
The consequence is that the waterproof market can no longer sensibly be divided into:
Gore-Tex versus everything else.
What Actually Matters in the Mountains?
The correct waterproof depends upon what the garment is expected to do.
For Scottish winter mountaineering, prolonged Alpine storms, expedition use and long periods exposed at belays, priorities might reasonably be:
Waterproofness → durability → construction → DWR performance → breathability
A rugged three-layer Gore-Tex or Gore-Tex Pro garment remains extremely compelling here.
For fast Alpine climbing, mountain running and high-output approaches, the priorities change:
Breathability → air permeability → low weight → drying speed → adequate waterproofness → durability
Here Pertex Shield Air, Futurelight and other highly breathable systems become particularly interesting.
For general UK hillwalking, a well-constructed 20,000 mm waterproof may already provide considerably more hydrostatic resistance than most users genuinely require.
The difference between a 20,000 and 28,000+ mm jacket may therefore be less important than:
How well does it fit?
How effectively does it vent?
Does it have useful pit zips?
How well does the hood work?
Will it accommodate a helmet?
How durable is the face fabric?
How heavy is it?
How easily can its DWR be maintained?
These questions may ultimately matter more than the logo on the chest.
The End of the “Gore-Tex Is Best” Argument?
Gore-Tex remains one of the most technically impressive waterproof systems available.
Its extremely high hydrostatic resistance, manufacturing standards, testing regime and decades of development continue to justify its position at the technical end of the market.
But waterproof technology has diversified.
A mountaineer producing enormous quantities of heat may benefit more from an extremely breathable 20,000 mm fabric than from a less air-permeable 28,000+ mm system.
Likewise, someone standing in driving Scottish rain for eight hours may make precisely the opposite decision.
There is therefore no universally “best” waterproof membrane.
There is a most appropriate waterproof for a particular activity.
Conclusion
The removal of PFAS represents far more than an environmental change in outdoor clothing.
It has altered the way modern waterproofs behave.
The membrane inside a modern technical shell may provide extraordinary resistance to water pressure, yet the PFAS-free DWR protecting its face fabric may require more frequent washing, reactivation and renewal than the fluorinated treatments used on previous generations of clothing.
That produces an apparent contradiction.
Modern waterproofs can be technically more sophisticated while appearing to wet out sooner.
Understanding the distinction between hydrostatic head, breathability, air permeability, membrane waterproofness and DWR performance is therefore increasingly important.
Gore-Tex continues to offer exceptionally high waterproof performance. Pertex Shield demonstrates that approximately 20,000 mm waterproofness combined with strong breathability can provide an excellent balance for mountain use. Pertex Shield Air, Futurelight, eVent, Dermizax and modern proprietary membranes demonstrate that breathability and air permeability can sometimes be more valuable than simply pursuing ever-higher hydrostatic-head figures.
The most important change, however, may be philosophical.
For decades consumers were encouraged to ask:
“Is it Gore-Tex?”
The better question today is:
“What am I actually going to use it for?”
Once that question is answered, the highest specification is not necessarily the best waterproof.
The best waterproof is the one whose balance of waterproofness, breathability, durability, weight and maintenance most closely matches the environment and activity in which it will actually be used.
