AATCC 22 Spray Test Explained for Buyers

Purpose and Scope

AATCC 22, formally the water repellency test by spray, measures how well a fabric surface resists wetting when water is sprayed onto it. It is one of the oldest and most widely used textile tests in the world, and it appears on an enormous number of specification sheets. It is also one of the most frequently misunderstood, because a high spray rating is routinely quoted as evidence that a product is waterproof. It is not, and the distinction matters commercially.

What the test measures is surface wetting. Water is sprayed at a tensioned fabric specimen held at an angle, and the operator observes how much of the surface has been wetted and rates the pattern against a standard scale. A fabric that beads water perfectly leaves no wetting and rates at the top of the scale. A fabric that absorbs water across its whole face rates at the bottom. Nothing in the procedure measures how much water passes through the fabric, because no pressure is applied.

What the method covers and what it does not

• Covers: the surface wetting behavior of a fabric, and by extension the condition of its durable water repellent finish
• Covers: comparison between two fabrics or two finishes under identical conditions
• Covers: lot-to-lot verification that a finish has been applied and is active
• Does not cover: water penetration under pressure, which is a hydrostatic head test
• Does not cover: seams, closures, needle holes or any product-level geometry
• Does not cover: immersion behavior, which requires a submersion method

That scope statement is the single most useful thing a buyer can take from this article. AATCC 22 tells you whether the surface finish is alive. It tells you nothing about whether water will get inside a bag. A fabric can rate 100 on the spray scale and still pass water under the pressure of someone kneeling on it, because the two mechanisms are different: one is surface wetting, the other is penetration through the coating and the fabric structure.

There is a useful historical point behind the method. It was developed to assess durable water repellent finishes on apparel, where the commercial question was whether a garment would wet out in rain. That is a surface question, and the test answers it well. It was never designed as a barrier test, and importing it into a waterproof bag specification as if it were one is the source of most of the confusion around it. Our ingress and seam test protocol places it in its correct position, as a finish control rather than a barrier proof.

Used correctly, AATCC 22 is cheap, fast and genuinely valuable. It takes a couple of minutes per specimen, needs no expensive apparatus, and it is the best available way to confirm that a finish is present and working across a production run. Use it for that, and use something else for everything else.

Apparatus and Setup

The apparatus is deliberately simple, which is part of why the method has survived for so long. It consists of a funnel, a spray nozzle with a defined set of holes, a specimen holder that clamps the fabric in a hoop, and a stand that holds the assembly at a fixed geometry above the specimen.

The setup elements that matter

• Specimen holder: a hoop that clamps the fabric flat and without wrinkles, at a fixed diameter
• Specimen angle: the hoop is held at 45 degrees to the horizontal
• Nozzle: a defined multi-hole spray head producing a controlled spray cone
• Nozzle to specimen distance: a fixed vertical distance defined by the method
• Funnel: delivers the full spray volume in a continuous, uninterrupted flow
• Stand: rigid, so the geometry does not move between runs

Geometry is the whole game. Because the method measures the pattern of wetting produced by a specific spray delivered at a specific angle from a specific distance, any drift in the geometry changes the test. A nozzle that is 10 mm closer produces a more concentrated impact and a lower rating. A hoop that sags by five degrees changes where water runs. Check and record the geometry at the start of each session rather than assuming the stand has not moved.

The specimen itself needs care. Cut it at the size the method specifies, avoid the selvedge and any creased or contaminated area, and handle it by the edges only. Fingerprints carry skin oils, and skin oils are exactly the kind of contamination that locally defeats a water repellent finish and produces a false low rating. This is a small discipline that removes a large category of spurious results.

Conditioning is required and frequently skipped. Bring the specimen to a standard atmosphere before testing, conventionally 20 plus or minus 2 degrees C at 65 plus or minus 4 percent relative humidity, and hold it long enough to equilibrate. A fabric tested straight from a dry oven or from a damp storeroom will not give the same result as one that has equilibrated, and the difference can be worth a full rating grade.

Water quality matters too. Use distilled or deionized water, because dissolved salts change surface tension and therefore change the wetting behavior being measured. Change the water regularly. Standing water in a laboratory bottle grows biological film within days, and that film changes the result in a way no one notices because it happens gradually.

Finally, provide a consistent viewing setup for rating. The assessment is visual, so the lighting and the viewing angle are part of the apparatus. Use a fixed light source, a fixed viewing position, and a fixed background. Rating the same specimen under a warm desk lamp and under a daylight booth can produce different grades, and that is measurement error rather than a material difference.

Spray Volume and Duration

The method defines a fixed volume of water for each test, and 250 mL is the figure that appears in the standard procedure. That volume is poured into the funnel and allowed to run through the nozzle onto the specimen in a continuous flow. The duration of the spray is therefore a consequence of the volume and the nozzle geometry rather than an independently set parameter, and it is typically in the region of 25 to 30 seconds.

Record the actual duration anyway. If the spray takes substantially longer or shorter than expected, something has changed: the nozzle is partially blocked, the wrong nozzle is fitted, or the funnel is not delivering a continuous flow. Duration is a free diagnostic, and logging it turns a silent apparatus fault into a visible one.

Why a fixed volume rather than a fixed time

• A fixed volume makes the delivered energy consistent even if the nozzle flow rate drifts slightly
• A fixed time would allow a partly blocked nozzle to deliver less water and produce a falsely high rating
• The volume is large enough to wet a poorly finished fabric completely, so the bottom of the scale is reachable
• The volume is small enough that a well-finished fabric is not overwhelmed by sheer quantity of water
• Continuous flow matters: an interrupted stream delivers the same volume over a longer period with different impact

The temperature of the water is specified because surface tension varies with temperature. Water that is too cold has higher surface tension and beads more readily, which flatters the fabric. Water that is too warm does the opposite. Use water at the temperature the method specifies, and check it rather than assuming the laboratory supply is correct.

After the spray, the method defines how the specimen is handled before rating. This usually involves tapping the specimen against a solid surface a defined number of times to remove loose surface water, because droplets sitting on the surface are not wetting. Handle every specimen identically, because an inconsistent tap changes the appearance and therefore the grade.

Then rate promptly. A wetted area continues to spread and darken after the spray stops, and a rating taken immediately and one taken two minutes later can differ. Set a fixed interval between the end of the spray and the rating, and hold to it across the whole sample set. Consistency here is worth more than precision elsewhere.

One practical note for high-volume programmes: run a known reference specimen at the start and the end of every session. If the reference grades the same at both ends, the session is valid. If it drifts, the apparatus or the water has changed and the results in between are suspect. This costs two minutes per session and it is the cheapest quality control available in this method.

Rating Scale 0-100 and Reference Photographs

The rating scale runs from 0 to 100 in steps of 10, and it is anchored to a set of standard reference photographs that show representative wetting patterns for each grade. The operator compares the sprayed specimen with the reference images and assigns the closest grade. This is a visual, comparative assessment, which is both its strength and its weakness.

Intermediate grades exist between those anchors, and the standard reference set covers the full range. The important commercial point is where to set the acceptance line. For a bag sold with a water resistant claim, a rating of 80 or above on the production fabric is a reasonable requirement, with 90 specified for premium programmes. Below 70 the finish is not doing useful work, and the fabric will wet out in sustained rain.

Now the weakness: the assessment is subjective. Two experienced operators looking at the same specimen will usually agree within one grade, but they will not always agree exactly, and near a specification boundary that is the difference between shipping and rejecting. This is inherent to a visual comparative method. The mitigations are worth applying.

Making a subjective scale usable in a contract

1. State the minimum acceptable grade numerically in the specification, for example 80 or above
2. Require the rating to be performed against the current standard reference set, and name it
3. Require two independent operators per specimen and average, or take the lower grade where they disagree
4. Require a photograph of each rated specimen alongside the grade, so the result is auditable
5. Run a reference fabric of known grade at the start and end of each session to validate the run

Photographs are the highest-value item on that list. A grade is an opinion; a photograph with a grade is evidence. Storage is nearly free, and when a dispute arises six months later, the photograph is the only thing that lets anyone re-examine the call. Require it in the RFQ and you will rarely need it, which is the point.

Note also that the scale is ordinal, not linear. The difference between 90 and 80 is not the same quantity of wetting as the difference between 50 and 40, and averaging grades across a sample set is statistically sloppy. Report the distribution and the minimum, not the mean, because the minimum is what reaches your customer.

Finally, be careful about what a rating means after use. A brand new fabric rating 100 tells you the finish was applied correctly. It does not tell you the fabric will still rate 100 after a season of abrasion and UV, and it certainly does not tell you it will rate 100 after washing. That is the next section, and it is where most commercial disappointment with this method originates.

Common Operator Errors

Because the method is simple, it is easy to run badly. The errors below account for the great majority of irreproducible spray ratings, and every one of them is preventable with a written procedure and a few minutes of discipline.

Contamination deserves extra emphasis because it is the most common and the least suspected. A water repellent finish works by presenting a low-energy surface, and skin oil, hand cream and mold release all raise the surface energy locally. A single fingerprint in the middle of a specimen can produce a wetting patch that reads as a failure, and the operator will report a low rating without any idea why.

The second most common issue is nozzle condition. The spray holes are small and they block with scale and with debris from the water supply. A partly blocked nozzle does not simply stop working; it changes the spray cone, so the delivered pattern is different and the rating is wrong in a way that looks plausible. Log the spray duration for every run and you will catch it the day it starts.

Then there is the temptation to re-spray. If a specimen rates badly, the natural instinct is to run it again and take the better result. That is selection bias and it invalidates the data. State in the procedure that each specimen is sprayed once, that a repeat requires a new specimen, and that both results are recorded if a repeat is run.

Train and qualify operators against a known set. Build a panel of specimens with established grades, including some deliberately poor ones, and have each operator grade them blind. An operator who cannot reproduce the known panel is not qualified, and re-qualification should happen whenever the method or the apparatus changes. This is standard practice under our ISO 9001:2015 documented procedures and it costs very little.

Consider a round-robin once a year. Send identical specimens to a second laboratory and compare grades. A systematic offset between two laboratories tells you something important about your setup, and it is far better to find it in a quiet week than during a dispute about a shipment.

Finish Durability Over Wash

A spray rating taken on new fabric is a snapshot of the day the fabric was made. The commercially relevant question is what the rating is after the product has been used, and that is a different measurement that requires its own protocol.

Durable water repellent finishes degrade through three main mechanisms: mechanical abrasion removes the finish from the fiber surface, contamination from skin oils and detergents masks it, and heat can either re-activate it or destroy it depending on how it is applied. A finish that rates 100 new can drop to 70 or below after 20 domestic wash cycles, and it will drop faster under abrasion than under washing alone.

Building a durability protocol

1. Establish the baseline: rate the fabric to AATCC 22 before any treatment
2. Define the aging cycle: a stated number of domestic wash cycles at a stated temperature, with a stated detergent
3. Rate after each cycle or at defined intervals, for example after 5, 10, 20 and 30 cycles
4. Include a re-activation step: tumble dry or press at a stated temperature, because many finishes recover with heat
5. Define the acceptance line at the end of the cycle, not at the beginning

The re-activation step is the one buyers omit and it is often the whole story. Many modern finishes, particularly the PFC-free chemistries now standard for the EU and UK markets, are designed to be re-activated by heat after washing. A fabric rated immediately after a wet wash and before drying will look far worse than the same fabric rated after tumble drying. Specify the sequence, or your durability data will be pessimistic and you will over-specify the finish.

Read that table as a shape rather than as data. The dip before drying and the recovery after heat are the characteristic signature of a working finish. If your fabric does not recover with heat, either the finish chemistry is not heat-activatable and needs a different care instruction, or the finish is being removed rather than masked, which is a durability problem rather than a testing artifact.

Abrasion is at least as important as washing for bags, and it is routinely ignored. A bag is set down, dragged and packed, and abrasion removes finish from the high points of the fabric weave. A protocol that only washes is testing the wrong degradation mechanism. Add an abraded-and-rated step, and if the product has a pack strap or a base panel, abrade those zones specifically.

Then decide what you will claim. If your product is sold as shower resistant with a care instruction that says re-activate with heat, a rating of 80 after 20 cycles is a defensible position. If your product is sold as waterproof, the spray rating on the outer face is largely irrelevant, because the barrier is the coating and the seam, not the finish. Say which you are relying on, and test that.

Finally, put the care instruction on the product. A finish that needs heat re-activation and never gets it will be reported as a defect by customers who followed no instruction at all. A single line on the care label, stating a drying temperature and time, protects the product and reduces returns.

When Spray Test Is Not Enough

There is a clear line where AATCC 22 stops being useful, and it is worth knowing exactly where it falls so you do not build a specification on top of a method that cannot carry it.

Signals that you need a different or additional method

• Your claim mentions waterproof, submersible, or any immersion language
• The product has seams, closures or needle holes, which the spray test does not evaluate
• The product will be kneeled on, sat on, or compressed against a wet surface
• The buyer is a marketplace or a large retailer asking for penetration evidence
• Your spray ratings are consistently high but the field still reports leaks

That last signal is the diagnostic one. If your fabric rates 100 and your customers still report water inside the bag, the spray test is doing its job perfectly and telling you about the wrong thing. The leak is coming through a path the method does not see, and the next step is to find the path rather than to improve the finish.

The most common and most costly error in this area is a specification that lists a spray rating as the sole water-related requirement on a bag sold as waterproof. It is cheap to run, it looks rigorous on a document, and it provides essentially no protection against the failure that will actually occur. Add a hydrostatic result for the material and a submersion result for the product, and keep the spray test where it belongs.

There is also a scope question about the finish itself. A spray rating tells you the surface is shedding water, which is a genuine benefit: a fabric that does not wet out stays lighter, dries faster and breathes better. Those are real performance advantages worth specifying for, independently of any waterproof claim. Just do not let them stand in for one.

A sensible minimum protocol for a mid-tier waterproof bag, then, is three lines: hydrostatic head to ISO 811 at 10,000 mm or higher for the material, a rain or spray assessment on the finished product for geometry, and a submersion test with a stated depth, duration and threshold for the claim. AATCC 22 can be added as a fourth line for finish control, and it is worth adding, but it is not one of the load-bearing three.

For the broader method comparison, including where enclosure codes from IEC 60529 fit and where they do not, see the water ingress test methods guide and the IPX rating explainer.

Specifying AATCC 22 in an RFQ

The method is only useful to a buyer if it is specified tightly enough that two parties will produce the same result. Below is a block you can paste into a request for quotation. Each line removes an ambiguity, and each is the kind of detail that otherwise gets decided by whoever runs the test.

1. Method: water repellency by spray to AATCC 22, current edition, with the edition stated
2. Specimen: production fabric in the production colorway, cut away from the selvedge, conditioned before testing
3. Conditioning: 20 plus or minus 2 degrees C at 65 plus or minus 4 percent relative humidity, held to equilibrium
4. Water: distilled or deionized, at the temperature stated in the method, changed regularly
5. Spray volume: the volume stated in the method, delivered in one continuous flow through the specified nozzle
6. Rating: against the current standard reference set, by two independent operators, taking the lower grade on disagreement
7. Acceptance: minimum grade stated numerically, for example 80 or above, on a defined sample size
8. Evidence: a photograph of each rated specimen, with the grade, the date and the operator recorded
9. Durability: a stated number of wash cycles, with a heat re-activation step and a post-wash acceptance grade
10. Session control: a reference fabric of known grade run at the start and end of each session

Add two procedural requirements that prevent the most common disputes. First, state that each specimen is sprayed once and that a repeat requires a new specimen. Second, state that the fabric may not be substituted after approval without a new test, because a finish change at the mill is invisible on a swatch and shows up only as a rating drop.

Then decide where the test sits in the schedule. Material-level spray testing belongs at incoming inspection on every fabric lot, because it is cheap and it catches a finish problem before cutting. Product-level testing belongs at first article and at pre-shipment. Keep the two separate in your documentation, because a fabric result and a product result answer different questions and conflating them is how specifications lose credibility.

On the commercial side, align the evidence with the money. Sampling runs 6 to 10 working days for a standard construction and 12 to 15 working days when the build is complex, and bulk production runs 35 to 50 days after sample approval, quoted FOB Xiamen with T/T 30/70 payment terms. Require the test report, with photographs, to be issued before the balance payment is due. That single linkage is the most effective quality lever available to a buyer.

One final practical note on cost: AATCC 22 is the cheapest water-related test you will buy. Because it is cheap, it is worth running on a larger sample than the more expensive methods, and a large sample gives you a distribution rather than a single point. Use it as your high-frequency screening tool, and reserve hydrostatic and submersion testing for the decisions that need them. That mix gives you better data for less money than any single method used alone. If you are building a protocol from scratch, start from the waterproof bag product range and the production and inspection workflow, and reference the finish requirements alongside REACH and RoHS declarations in one compliance file. Finish and barrier requirements are normally written together in the custom waterproof bag development brief.

Frequently Asked Questions

Q1: What does the AATCC 22 spray test measure?

A: It measures how well a fabric surface resists wetting when a fixed volume of water is sprayed onto a specimen held at 45 degrees. The wetting pattern is rated from 0 to 100 against standard reference photographs. It assesses the durable water repellent finish, not water penetration, and it applies no pressure at all.

Q2: Is a spray rating of 100 the same as waterproof?

A: No. A rating of 100 means no wetting of the fabric surface under a spray with no pressure behind it. Waterproof requires resistance to penetration under pressure, which is measured by a hydrostatic head test such as ISO 811, plus product-level testing of seams and closures.

Q3: How much water is used in the AATCC 22 test?

A: The method specifies a fixed volume, commonly 250 mL, poured into the funnel and delivered through the nozzle in one continuous flow. The spray lasts roughly 25 to 30 seconds depending on nozzle condition. Log the actual duration, because a change indicates a partly blocked nozzle.

Q4: What spray rating should I require for a bag?

A: Require 80 or above for a water resistant claim on production fabric, and 90 or above for premium programmes. Below 70 the finish is not doing useful work and the fabric will wet out in sustained rain. State the minimum grade numerically in the specification so the result is not arguable later.

Q5: Why do two laboratories report different spray ratings?

A: Usually because of conditioning, water quality, nozzle condition, operator judgement or lighting at the rating step. AATCC 22 is a visual comparative method, so it has inherent operator variance. Require two operators, a fixed interval before rating, and photographs to make the result auditable.

Q6: Does the spray rating drop after washing?

A: Yes, typically. A good durable water repellent finish may drop before drying and then recover after heat re-activation, so rate after drying rather than before. Expect a good finish to hold around 80 after 20 cycles with re-activation, and a marginal one to fall to 50 or below.

Q7: How do I test finish durability properly?

A: Establish a baseline rating, define a wash cycle with a stated temperature and detergent, rate at defined intervals such as 5, 10, 20 and 30 cycles, include a heat re-activation step, and set the acceptance line at the end of the cycle. Add an abrasion step, because bags abrade more than they wash.

Q8: What is the most common operator error in spray testing?

A: Handling the specimen face with bare fingers. Skin oils raise the surface energy locally and produce a wetting patch that reads as a failure. Handle specimens by the edges or with clean gloves, and condition them at a standard atmosphere before testing.

Q9: Should I use distilled water for the spray test?

A: Yes. Dissolved salts in tap water change surface tension and therefore change the wetting behavior being measured. Use distilled or deionized water at the temperature stated in the method, and change it regularly, because standing water grows biological film within days.

Q10: When is the spray test not enough?

A: Whenever the claim is waterproof or submersible, whenever the product has seams, closures or needle holes, and whenever the product will be compressed against a wet surface. In those cases add hydrostatic testing for the material and submersion testing for the finished product.

Q11: Can the spray test detect a leaking seam?

A: No. It uses a flat fabric specimen and evaluates only the surface finish. Seams, welds, closures and needle holes are product-level paths that require a submersion test, an air decay check on a sealed chamber, or a rain test on the assembled product.

Q12: How often should spray testing be run?

A: Run it on every incoming fabric lot as a finish control, because it is cheap and fast. Run product-level testing at first article and at pre-shipment. Keep the material result and the product result separate in your documentation, because they answer different questions.

Q13: What should I record on a spray test report?

A: The method edition, the specimen identity and colorway, the conditioning record, the water type and temperature, the spray volume and duration, the grade assigned by each operator, the acceptance threshold, and a photograph of each rated specimen with the date.

Q14: How does spray testing fit the production schedule?

A: Material spray testing happens at incoming inspection before cutting. Product testing happens at first article and pre-shipment, within a bulk lead time of 35 to 50 days after sample approval, quoted FOB Xiamen with T/T 30/70 payment terms, with the report issued before the balance payment is due.

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