Which membrane should I choose if I need high breathability and high water resistance at the same time?

The two membranes achieve the target in opposite ways, and the choice usually follows from which requirement is tighter. An ePTFE membrane transmits through a pore structure, so it delivers high transmission if the pores are kept open, and its water resistance comes from the pore structure resisting liquid water. A TPU membrane transmits through the polymer itself and holds water out as a continuous film, so it typically makes the water resistance requirement the easier of the two. The decision belongs in the specification before any lamination discussion, because the membrane decides which requirement binds.

Our laminate lost breathability after bonding - what usually causes that?

On a porous membrane, the usual cause is something filling or compressing the pore structure. A wet adhesive can be drawn into the pores, and a nip pressure that was raised to improve the peel figure can compress them. That is why a porous build is normally bonded with hot-melt adhesive lamination using controlled film placement, and why pressure has to be judged against the transmission figure and the peel figure together rather than against one of them.

Should I worry about a face fabric finish migrating into the membrane?

Yes, on a porous membrane. A repellent finish or a softener on the face fabric can transfer into the pore structure during bonding or later in use, and a pore that has been wetted by a surfactant behaves differently from a dry one. Check the face fabric finish and the adhesive chemistry against the membrane before the build is locked, rather than after a transmission complaint arrives.

We ran the same line settings for a TPU build as for an ePTFE build and got handling marks - why?

Because the binding constraint changed. A TPU film is heat-sensitive and softer, so it is more inclined to stick to itself or to the roll face under warmth and pressure, and it also blocks more easily on the roll. The bonding temperature and the tension have to be set from the film's own behaviour and from the face fabric's limit, not carried across from a porous membrane build.

Do I need a protection print or an extra coating on a TPU build?

Usually not for water resistance, because the continuous film already holds water out. A protection layer borrowed from a porous build adds mass without improving the property it was taken from — mass is verified under GB/T 4669, and the programme usually notices the difference. Keep the protection decision separate from the membrane decision.

ePTFE and TPU Membrane Lamination: Two Membranes, Two Different Sets of Requirements

For fabric development, sourcing and quality control teams Prepared by the Technical Department, Suzhou TTK Textile Technology Group Co., Ltd. The standard numbers below come from TTK's commissioned testing scope; the process statements come from TTK's own capability record.

Bottom line

An ePTFE membrane asks the line to protect a porous structure; a TPU membrane asks it to control heat and moisture, so settings do not transfer.

1. Two membranes that achieve breathability in opposite ways

	ePTFE membrane	TPU membrane
Structure	Expanded PTFE — a microporous structure, with air spaces forming the transmission path	A monolithic film, with no pores; available in transparent and matte finishes
How vapour passes	Through the pore structure	Through the polymer itself, by molecular transport
Water resistance	Comes from the pore structure resisting liquid water while vapour passes	Comes from the film being continuous
What the membrane is sensitive to	Anything that fills or wets the pores, and anything that compresses them	Heat at the bonding temperature, and the tackiness of the film on the roll
Handling character	Relatively stiff and dimensionally stable	Softer and more elastic

Both sit in this scope alongside plain, non-expanded PTFE and PVDF membranes, so the membrane choice is a genuine decision rather than a default. The membrane chemistry decides which lamination requirement is the binding one, and the two membranes below bind on different things.

2. What an ePTFE membrane demands of the lamination process

The pore structure is the product. Everything in the lamination process has to be arranged so that the pores are still open, still hydrophobic and still the same shape after bonding:

The adhesive must not be drawn into the pores. A wet adhesive applied against a porous membrane can be pulled into the pore structure, which blocks part of the transmission path and leaves a localised stiff, glossy patch. This is the single strongest argument for hot-melt adhesive lamination with controlled adhesive-film placement on an ePTFE build: the adhesive arrives as a film, and the dose and position are a purchased specification rather than a live pick-up.
Nip pressure has to be set against pore collapse, not only against bond strength. Pressing harder improves the immediate peel figure and can compress the pore structure, which reduces transmission. The requirement has to be written as transmission and peel, because either one alone can be met by sacrificing the other.
The adhesive and the face fabric's finish have to be compatible with the membrane. A face fabric carrying a repellent or softener finish can transfer that chemistry into the membrane during bonding or during later use, and a pore that has been wetted by a surfactant behaves differently from a dry one.
Both membrane faces are not equal. A membrane face that carries a protective treatment behaves differently in bonding from the untreated face, so the specification has to say which face is bonded to the face fabric and which faces the inside of the garment.

Practical wording for the specification: name the membrane, name which face is bonded, state the transmission method, and state the peel requirement with a wash tier. Then let the lamination settings be verified against both figures together.

3. What a TPU membrane demands of the lamination process

A TPU membrane has no pores to flood, so the risk profile is different:

Heat sensitivity is the constraint, not pore damage. The bonding temperature has to be set from the film's own behaviour and the face fabric's limit, not from the ePTFE settings. Running a TPU build at an ePTFE activation temperature is one of the commonest ways to lose a roll.
Roll tackiness and blocking. A softer film is more inclined to stick to itself or to the roll face under warmth and pressure, which shows up as handling marks and as tension variation through the line.
Elastic behaviour belongs in the peel clause. Because the film is elastic, the bond is judged under strain as well as in the flat state, and a peel figure taken from a flat specimen may not describe the build that is actually worn.
The continuous film is what holds the water out. A TPU build usually carries a high water resistance figure from the film itself, so an ePTFE-derived habit of adding a protective print or a heavier coating to secure water resistance is unnecessary weight on a TPU build.

4. The two requirement sets side by side

Requirement	On an ePTFE build	On a TPU build
Adhesive family	Hot-melt adhesive lamination with controlled film placement is the safer starting point	Hot-melt adhesive lamination is usually also the choice, but the activation window is set by the film rather than by the membrane
Nip pressure	Set against pore collapse and verified by a transmission figure as well as by peel	Set against bond strength and against blocking, with less concern about structure damage
Bonding temperature	Set from the adhesive system and the face fabric finish	Set from the film's heat sensitivity, and kept well inside it
Transmission clause	The pore structure is the transmission path, so the method has to be stated explicitly — GB/T 12704.2-B for a waterproof-and-breathable construction, or JIS L1099-B1 or ASTM E96	The same clause applies, but the figure is set by the film and is less sensitive to bonding pressure
Water resistance clause	Read under GB/T 4744, ISO 811 or AATCC 127, with the ramp rate settled in writing	The same clause applies, and the continuous film usually makes it the easier of the two requirements
Peel clause	FZ/T 01010, with a wash tier under GB/T 8629, ISO 6330 or AATCC 135	FZ/T 01010, with the same wash tier, and a note on behaviour under strain
Contamination risk	Higher — anything that wets a pore reduces performance	Lower — there is no pore structure to contaminate
Handfeel outcome	Firmer; the inside usually needs a liner or a protection print	Softer and more elastic, which is often the reason the membrane was chosen

5. Common pitfalls

Pitfall	What it looks like	Cause
The ePTFE settings carried over to a TPU build	Localised gloss and handling marks on the laminate	The bonding temperature was set from the wrong membrane
Wet adhesive used against an ePTFE membrane	Transmission drops and stiff patches appear	Adhesive was drawn into the pore structure
Nip pressure raised to fix a peel complaint	Peel passes and the transmission figure falls	Pressure was treated as a single-objective control
Extra weight added to a TPU build "for protection"	The laminate is heavier than the programme needs	A habit borrowed from a porous build, where a protection layer does have a purpose
A transmission figure quoted with no method	Two suppliers disagree about the same membrane	GB/T 12704.2-B, JIS L1099-B1 and ASTM E96 are different methods and are not interchangeable
The bonded membrane face not specified	Two builds using the same membrane behave differently	The treated and untreated faces of a membrane are not equivalent in bonding
A peeling figure taken only in the flat state on an elastic film	The figure passes and the worn garment still separates	The bond was never judged under strain

6. Working order for development teams

Fix the membrane and the bonded face before any lamination discussion, because the membrane decides which requirement binds.
Fix the adhesive family next, and on a porous membrane prefer film-fed hot-melt lamination rather than a wet adhesive.
Set pressure against both the transmission figure and the peel figure, never against one of them.
Set temperature from the membrane and the adhesive system, and from the face fabric's own limit.
Name the transmission method and the water resistance standard in the specification, with the ramp rate for the hydrostatic clause.
Add a wash tier to the peel clause, under GB/T 8629, ISO 6330 or AATCC 135.
Keep a retained sample per lot, so a transmission or peel complaint can be traced to a specific roll.

Criteria Table: How to Tell Whether the Membrane Requirement Was Set Correctly

Criterion	What Passing Looks Like	Common Failure
The membrane is named, not implied	The specification names ePTFE, plain PTFE, TPU or PVDF, rather than saying only "membrane"	The lamination settings are set for one membrane and applied to another
The bonded membrane face is stated	The specification says which face is bonded to the face fabric and which faces the wearer	Two builds using the same membrane behave differently, and the cause is never located
The adhesive family suits the membrane	A porous membrane is bonded with a film-fed hot-melt system rather than with a wet adhesive	A wet adhesive is drawn into the pore structure and transmission falls
Nip pressure is judged on two figures	Both the transmission figure and the peel figure are reported for the same build	Pressure is raised until the peel figure passes, and the transmission figure is never re-checked
The transmission method is named	The transmission clause names GB/T 12704.2-B, JIS L1099-B1 or ASTM E96 for a waterproof-and-breathable build	A figure is quoted with no method, so two suppliers appear to disagree about the same membrane
The water resistance clause names its standard	The clause names GB/T 4744, ISO 811 or AATCC 127, and the ramp rate is fixed in writing	A hydrostatic figure is quoted with no standard, and the ramp rate question surfaces after the bulk order
The peel clause carries a wash tier	The peel requirement names a tier and a washing standard under GB/T 8629, ISO 6330 or AATCC 135	An as-received peel figure is handed over as the whole answer
The bonding temperature is set from the right membrane	The temperature window is derived from the membrane and the adhesive system, and stays inside the face fabric's limit	An ePTFE temperature is used on a TPU build, and handling marks or localised gloss appear
Contamination risk on a porous membrane is addressed	The face fabric finish and the adhesive chemistry are checked for anything that could wet the pore structure	A repellent finish or a softener migrates into the membrane and the transmission figure drifts
A TPU build is not given unnecessary protection weight	The build keeps the film as the water-resistance element, and mass is verified under GB/T 4669	A protection print or extra coating borrowed from a porous build raises mass without improving performance
Strain behaviour is covered on an elastic film	The peel requirement notes that the bond is judged under strain as well as in the flat state	The flat peel figure passes and the worn garment still separates
A retained sample exists per lot	A same-lot retained sample is kept so a transmission or peel complaint can be traced to a specific roll	No retained sample survives, and the complaint cannot be separated from a later process change

ePTFE and TPU Membrane Lamination: Two Membranes, Two Different Sets of Requirements