Waterproof Ratings for Fishing Rain Gear: Hydrostatic Head, Breathability, DWR and Seam Sealing Explained

A seam sealed jacket is a waterproof jacket whose stitched seams have been covered on the inside with waterproof tape, so rain cannot get in through the needle holes. Seam sealing is only one of four numbers and terms that decide whether fishing rain gear keeps an angler dry. The other three are hydrostatic head (how much water pressure the fabric resists), breathability (how much sweat vapour gets out) and DWR (the finish that makes water bead on the outside).

This guide is for product developers at fishing apparel brands and for distributors adding a rain-gear line. It explains what each rating measures, how it is tested, and which conditions change the result. It also shows how to write the ratings into a specification and check them when the goods arrive. It does not rank products. CYCLODRY's own fabric figures are on each product page and in current product specifications, not in this article.

Waterproof vs Water-Resistant vs Water-Repellent

The three words describe different properties and are tested differently.

Term	What it describes	How it is tested	Typical fishing product
Water-repellent	The surface sheds water so drops bead and roll off	Spray test such as AATCC TM22: a wetted pattern is compared with a rating chart	Any shell with a DWR finish; softshells
Water-resistant	The fabric holds back some water pressure but will wet through in sustained rain	Hydrostatic pressure test, low result; seams usually not sealed	Softshells, insulated jackets with storm flaps
Waterproof	Fabric, seams and closures together keep out sustained rain	Hydrostatic pressure test on fabric and seams, plus garment-level checks	Rain jackets and foul-weather bibs with taped seams

AATCC's TM22 summary describes the spray test as applicable to any fabric, with or without a repellent finish; it rates how water spreads across the surface, not whether water gets through. A fabric can score well on a spray test and still leak at a seam. That is why a "water-repellent" claim and a "waterproof" claim need different evidence.

There is also a garment standard for rainwear. In Europe, protective clothing against rain is now covered by EN ISO 24232, which the Swedish Standards Institute lists as replacing EN 343:2019. Its scope covers precipitation, fog and ground humidity, and it explicitly excludes protection against water splashes and waves. For offshore fishing gear that is worth knowing: a rating built around rain does not describe spray coming over the gunwale.

Hydrostatic Head: The Test and What Rating Bands Mean

Hydrostatic head is the water pressure a fabric withstands before water comes through. It is measured under ISO 811 or, in the US, AATCC TM127. iTeh's catalogue entry for EN ISO 811:2018 summarises the principle. One side of the specimen faces steadily increasing water pressure until water appears in three places, and the pressure at the third point is recorded. AATCC's TM127 summary describes the same purpose: the resistance of a fabric to water penetration under hydrostatic pressure.

A hydrostatic head rating is usually quoted in millimetres of water column. A rating of 10,000 mm means the fabric held back the pressure of a column of water ten metres high. Laboratories also report centimetres of water, millibar or pascals. One millimetre of water is about 9.8 Pa, so convert before comparing a lab report with a hang tag.

Brands and retailers use rough bands to describe what a number means on the water. These are general industry usage, not thresholds from a standard:

Hydrostatic head (general usage)	How it is usually described
Around 3,000 mm	Water-resistant: showers and spray
Around 5,000 mm	Steady rain for limited periods
10,000 mm and above	The common benchmark for offshore and foul-weather rain gear
20,000 mm and above	Marketed for prolonged, heavy exposure

Pressure in use is not only rain. Kneeling on a wet deck, sitting on a cooler or a pack strap pressing on a shoulder all push water through fabric at much higher local pressure than falling rain. That is why bibs are often reinforced at the knee and seat.

Two conditions matter more than the headline number. First, the specimen state: a new fabric tests higher than the same fabric after laundering and abrasion. Second, the area tested: a fabric result says nothing about seams, zips or pocket openings. Ask whether the number is for new fabric or for fabric after a stated number of washes.

Breathability: MVTR, RET and "10K/10K"

Breathability describes how much water vapour passes out through the fabric. It is reported in two different ways.

RET (resistance to evaporative heat transfer) comes from the sweating guarded hotplate in ISO 11092. Centexbel, a Belgian textile laboratory, describes the method as a heated plate that simulates skin. The plate is run dry to measure thermal resistance and "sweating" to measure water-vapour resistance, reported as Ret in m²·Pa/W. Because it is a resistance, a lower RET means a more breathable fabric.

MVTR (moisture vapour transmission rate) reports how many grams of water vapour pass through a square metre of fabric in 24 hours. Higher means more breathable. Several methods produce an MVTR. ASTM's E96/E96M-24a alone contains a desiccant method and a water method. Its own text warns that a result obtained under one method and set of conditions cannot be used to predict the result under another.

"10K/10K" is shorthand on hang tags: roughly 10,000 mm hydrostatic head and 10,000 g/m²/24h vapour transmission. It is useful for marketing and useless in a specification unless both methods are named. Two "20K" fabrics tested by different MVTR methods may not be comparable at all.

How does a fabric keep rain out and still let vapour through? A microporous membrane has pores far smaller than a water droplet but larger than a water-vapour molecule. GORE-TEX explains its ePTFE membrane in exactly these terms. Solid (monolithic) PU and TPU films work differently: vapour diffuses through the polymer instead of passing through pores.

2-Layer, 2.5-Layer and 3-Layer Constructions

What are rain jackets made of? Almost always a face fabric plus a waterproof layer, and the number of layers describes how that waterproof layer is protected on the inside. The descriptions below are standard industry usage.

Construction	How it is built	Strengths	Trade-offs	Common fishing use
2-layer	Coating or membrane bonded to the face fabric; a separate hanging liner (mesh or taffeta) protects it	Comfortable hand, lower cost, liner adds warmth	Heavier, bulkier, liner can hold water	Bibs, deck jackets, PU-coated foul-weather gear
2.5-layer	Coating or membrane on the face fabric with a thin printed or sprayed protective layer instead of a liner	Very light and packable	Less durable; can feel clammy against skin	Packable emergency shells
3-layer	Face fabric, membrane and a thin knit backer laminated into one fabric	Most durable and stable; best for hard use	Higher cost; stiffer hand on heavy face fabrics	Premium offshore rain jackets

Our waterproof breathable fishing rain jacket is a 3-layer laminate with fully taped seams. The foul-weather fishing bib pants use a coated 2-layer construction suited to deck work. Both product pages carry the current specifications.

DWR: What It Does and the PFAS-Free Transition

What is DWR? DWR means durable water repellent: a finish applied to the outside of the face fabric so that water beads and rolls off. It is not the waterproof layer. Its job is to stop the face fabric from soaking up water ("wetting out"). A wetted-out face fabric adds weight, feels cold and blocks vapour from leaving through the membrane. GORE-TEX's FAQ notes that a garment with a saturated outer layer can feel damp and clammy even when it is not leaking. That is the most common reason a customer returns a jacket that is technically still waterproof. The same page describes the fix: when water stops beading, the DWR needs reactivating with washing and heat, or reapplying.

A DWR coating, DWR treatment and DWR fabric are the same idea seen from different sides: the chemistry, the process and the finished material. For buyers the important question is which chemistry.

For decades, the most effective DWRs were fluorinated, which places them in the PFAS family. The industry moved from long-chain (C8) to short-chain (C6) fluorochemistry and is now moving to fluorine-free finishes. The regulatory picture below was checked on 2026-10-20 and is changing quickly. It is a summary, not legal advice.

California. The state's textile law (AB 1817) defines "outdoor apparel for severe wet conditions" and gives outerwear for offshore fishing as an example, in Health and Safety Code §108970. The same section defines regulated PFAS as intentionally added PFAS, or total organic fluorine at or above 100 ppm from 2025 and 50 ppm from 2027. A 2025 Assembly committee analysis records that textile articles containing regulated PFAS have been banned from sale in the state since 1 January 2025. Bureau Veritas's summary of the law as signed adds two points. Severe-wet-conditions apparel has until 1 January 2028 to comply, and since 2025 it must carry a PFAS disclosure, including online.
European Union. The European Commission restricted PFHxA, the substance group behind much C6 chemistry, in consumer textiles "such as rain jackets". Transition periods run from 18 months to five years depending on the use; the exact dates are in the Annex XVII entry of Regulation (EU) 2024/2462. A broader EU restriction covering PFAS as a class was still under evaluation when we checked.

For a brand, three consequences follow. Specify fluorine-free DWR now, rather than relying on an exemption that ends. Expect lower oil resistance: GORE-TEX notes that its PFAS-free DWR is less resistant to oils and needs more frequent care, which matters around fish slime, sunscreen and fuel. And ask for evidence of the chemistry, such as the finish supplier's declaration or a total organic fluorine test, not only a beading demonstration.

Seam Sealing: What Is a Seam Sealed Jacket?

Every stitch puts a hole through the waterproof layer. GORE-TEX's FAQ puts it directly: seam tapes are used to seal the seams in apparel to make them waterproof. Seam sealing means covering each seam on the inside with a heat-activated tape. Some coated fabrics use a liquid seam sealer instead. Some designs avoid stitches altogether with welded or bonded seams.

Fully seam sealed (fully taped): every seam that passes through the waterproof layer is taped. This is the standard for real rain gear.
Critically seam sealed: only the seams most exposed to rain are taped, typically shoulders, hood, upper back and sometimes armholes. It is cheaper and lighter, and it suits water-resistant shells and lighter jackets that will not be worn in sustained rain.

Two production points follow from this. Any decoration that pierces the shell after taping creates new holes. GORE-TEX notes that embroidering a logo on a sealed garment requires the seams to be resealed. For rain gear, plan logos as heat transfers or as embroidery on a patch or panel before taping. Also, tape width, tape type and the temperature, pressure and speed settings must match the fabric, so tape adhesion belongs in the inspection, not just the spec.

Waterproof zippers are not all waterproof. YKK distinguishes its AquaGuard zips from its watertight AQUASEAL and PROSEAL lines. AquaGuard uses a polyurethane film to shed water and is classed as water-resistant; the watertight lines are designed to stop water penetrating the exposed surface completely. Most rain jackets pair a water-resistant zip with a storm flap or an internal gutter. Name the zip type in the spec and say whether a storm flap is required.

Fabric Combinations: Polyester or Nylon With PU, TPU or ePTFE

Is polyester waterproof? Polyester fibre absorbs very little water, but a woven or knitted polyester fabric has gaps between the yarns, so is 100% polyester waterproof? Not on its own. It becomes waterproof when a coating or membrane is added and the seams are sealed. The same is true of nylon.

Element	Options	What to know
Face fabric	Polyester or nylon, plain or ripstop	Nylon is generally the more abrasion-resistant face for the weight; polyester is usually cheaper and absorbs less water
Coating	PU (polyurethane), applied as a liquid	Economical, robust on heavy bibs; breathability limited
Film	TPU or PU film laminated to the face	Solid film; vapour diffuses through it; good for welded constructions
Membrane	ePTFE or ePE microporous membranes	Highest breathability; GORE-TEX describes its newer ePE membrane as made without intentionally added PFAS
Finish	DWR on the face	Specify fluorine-free chemistry; see the DWR section

A packable softshell fishing jacket sits at the other end: a bonded stretch fabric with a DWR finish, built to be water-resistant and breathable rather than waterproof. It is the right product for wind and showers, and the wrong one for a day of offshore rain. Getting that distinction right on the hang tag avoids returns.

Writing It Into a Spec and an Inspection

A rain-gear specification should state each rating with its method and specimen condition. A number on its own is not enough. Add these lines to the tech pack; our fishing shirt tech pack guide shows the overall structure.

Spec line	What to write	What to check at sample and bulk
Construction	Face fibre and weave, coating or membrane type, 2 / 2.5 / 3-layer, backer	Fabric article and lot match the approved sample
Hydrostatic head	Target, method (ISO 811 or AATCC TM127), and condition: new and after an agreed number of washes	Lab report on the production lot, not a mill catalogue page
Breathability	Target, method (ISO 11092 RET, or the named MVTR method and conditions)	Report states the method; do not compare results from different methods
DWR	Chemistry (fluorine-free or declared), spray rating method, condition after washing	Supplier chemistry declaration; spray test after laundering
Seams	Fully or critically taped; tape type and width; which seams	Visual check of every taped seam; tape peel and edge lift; water test on a garment
Closures	Zip type (water-resistant or watertight), storm flap, cuff and hood closures	Zip model on the bill of materials matches the delivery
Labelling	Market-specific claims and any PFAS disclosure the destination market requires	Hang tag and care label proofs approved before printing

For inspection, a buyer can do three things without a laboratory. Look inside every garment in the sample for lifted tape edges, wrinkles and gaps at seam crossings. Water-test a finished garment, for example by filling the hood and sleeves or spraying the shoulders, and check the inside for wet spots. And compare the zip, tape and fabric references on the delivered goods with the approved bill of materials. CYCLODRY includes seam-seal checks in its four-stage inspection for waterproof styles. The laboratory figures for any fabric you shortlist come from test reports, which you should request for the specific fabric and colour.

For rain jacket manufacturers, the questions to put in writing are simple. Which method produced each number? Was the specimen new or washed? Is the DWR fluorine-free? Which seams are taped? Which test can be run on the production lot? Our guide to finding a fishing apparel manufacturer covers how to ask them as part of a sourcing inquiry.

Build Your Rain-Gear Line With CYCLODRY

Browse the fishing jackets and rain gear category for the jackets, bibs and softshells most programmes start from. Then tell us the conditions your customers fish in, the markets you sell in and the ratings you need on the label. We will say which fabric, membrane, DWR and seam construction fit, and which test evidence exists or can be arranged for the production lot.

Contact CYCLODRY about waterproof fishing rain gear for your brand to go through the spec together.

References

The linked pages are public summaries of test methods, laboratory and standards-body descriptions, technology providers' descriptions of their own materials, and government or test-laboratory summaries of regulation. They describe general methods and third-party technologies; they do not establish test results, ratings or certifications for CYCLODRY products, and they are not legal advice for any market.