My supplier just says "three-proof" - what should I ask for instead?

Ask for the three properties separately, because they are judged in three different ways. Water repellency is a spray rating under AATCC 22, ISO 4920 or GB/T 4745; oil repellency is a grade on the grade scale; stain repellency is a stained-swatch observation. A single "three-proof" line lets the supplier choose which one was demonstrated.

How do I test whether three-proof survives washing twenty times?

Name the tier and the washing standard together. The post-wash figure has to be tied to GB/T 8629, ISO 6330 or AATCC 135, because those three do not apply the same mechanical action, and the tier has to be the one your claim names. A count with no standard, or a standard with no count, cannot be compared across suppliers.

The report gives a grade for oil repellency but no standard number - is that normal?

Yes, and it should be stated plainly rather than filled in. In this scope, three-proof and oil repellency items have measured data in TTK's external test records, but the testing menu carries no independent standard number for them, so the result is offered as data and no standard number is attached. What you should not accept is a spray rating standard printed next to an oil grade, because that is a different test.

We need fluorine-free finishing and a high oil repellency grade at the same time - can both be met?

Usually not on one route. A fluorine-free system typically reaches a lower oil grade than a fluorinated system, with the usual trade comparison around grade 2–3 against grade 6–8. The specification has to name which requirement is binding, and the supplier has to say plainly whether the chosen chemistry carries it, rather than leaving the collision to be discovered on bulk.

Washing twenty times dropped the oil grade but the water grade held - is the finish faulty?

Not necessarily. The three properties share the same film but decay at different rates, and oil repellency is the one that depends most on the low-surface-energy chemistry. What matters is whether the result is judged against the tier you wrote into the specification, and whether the retention rule was an absolute grade or a share of the as-received figure.

Three-Proof Finishing and Wash Durability: How Water, Oil and Stain Repellency Are Tested After Washing

For fabric development and sourcing 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

Three-proof finishing is one recipe carrying three properties, and each survives washing at its own rate under its own test method.

1. Three properties, one recipe, three different judgement methods

"Three-proof" means water repellency, oil repellency and stain repellency applied in the same finishing pass. The three are judged in three different ways, which is where most specifications go wrong:

Property	How it is judged	What the supplier can attach
Water repellency	Spray rating, read under AATCC 22 in points or under ISO 4920 and GB/T 4745 in grades	The standard number and the result
Oil repellency	Oil repellency grade, judged by the grade scale rather than by a spray test	Measured data exist in TTK's external test records for three-proof and oil repellency items, but the testing menu carries no independent standard number for them, so a result can be discussed and a standard number cannot be attached
Stain repellency	Staining and cleaning behaviour, judged by the buyer's own stained-swatch comparison	Available as a finishing process; no test values and no standard numbers are quoted here

One line in a specification collapses all three into one word. If the specification says "three-proof" and nothing else, the supplier is free to choose which of the three was actually demonstrated, and the buyer has no basis to object.

2. Why one recipe gives three different durability curves

The three properties share the same film on the surface of the fibre, but they do not decay at the same rate:

Water repellency depends on surface energy. It is the property that a silicone-based or polyurethane-based fluorine-free finish can hold best.
Oil repellency needs a lower surface energy than water repellency, which is why fluorinated chemistry has historically been the route to a high oil grade. A fluorine-free system typically reaches a lower oil grade — the usual trade comparison is around grade 2–3 against grade 6–8 for a fluorinated system.
Stain repellency depends on the same film plus anti-soiling behaviour, and it generally tracks the oil result more closely than the water result.

Practical consequence: a report reading "three-proof passed" tells you nothing about which property was measured, at which tier, or how far the weakest of the three fell. Ask for the three separately.

3. The wash durability protocol: four things that have to be written down

Wash durability is not a property of a finish; it is a property of a test protocol. Four items decide the result:

The tier. Is the figure as-received, after 1–5 washes, after 6–10, after 11–15, or after 20 or more? The tier the brand writes into its claim is the tier that has to be tested.
The washing standard. GB/T 8629 for domestic orders, ISO 6330 for European orders, AATCC 135 for North American orders. They do not apply the same mechanical action, so a tier tested under one cannot be quoted as the same tier under another.
The retention rule. Is the requirement written as an absolute grade after washing, or as a percentage of the as-received grade? A retention rule is easier to satisfy across colours; an absolute rule is easier to enforce in a claim.
The specimen and averaging rule. The average of the specimen set and the single worst specimen are two different numbers, and a complaint is usually built on the worst one.

A tier without a washing standard, and a washing standard without a tier, are both unreadable. Write all four items into the technical specification before quotation, not after the bulk order fails.

4. Where the fluorine-free choice lands on each of the three

A three-proof requirement and a fluorine-free requirement can point in opposite directions, and the specification has to say which one wins.

If the requirement is…	Fluorine-free (C0) route	Fluorinated (C6) route
Fluorine-free chemistry mandatory	Carries the requirement	Does not carry the requirement
High water repellency grade after washing	Achievable when the crosslinking route and curing are controlled	Achievable, with a wider process window
High oil repellency grade	Normally weaker; the trade comparison is around grade 2–3 against grade 6–8	The route to a high oil grade
Stain repellency at high grade	Tracks the oil result, so it is limited by the same ceiling	Stronger
Cost and process simplicity	Fewer chemistry constraints	Additional compliance handling for restricted markets

The honest sentence for a buyer to ask for is: which of the three properties is binding, at which tier, under which washing standard — and then the answer that says plainly whether the chosen route carries each one.

5. Common pitfalls

Pitfall	What it looks like	Cause
"Three-proof passed" as a whole result	One line covers three properties that were judged three different ways	No property, tier or standard was ever named
An oil grade quoted with a spray standard number	The report attaches AATCC 22 or GB/T 4745 to an oil repellency figure	Those are water repellency tests; oil repellency is a grade scale
A wash count with no washing standard	The spec says "washes 20 times"	GB/T 8629, ISO 6330 and AATCC 135 do not apply the same mechanical action
The tier tested is not the tier claimed	Post-wash data exist for one tier and the marketing claim names another	Testing was done once, and the claim was written later
The average is quoted and the worst specimen is not	Bulk is rejected on one specimen while the report average passes	The averaging rule was never agreed
Fluorine-free chosen and the oil requirement left in place	The programme requires a high oil grade and a fluorine-free finish at the same time	The trade-off was never put in writing

6. Working order for development teams

Split "three-proof" into three written requirements, each with its own grade and its own judgement method.
Attach the tier and the washing standard to every post-wash requirement — GB/T 8629, ISO 6330 or AATCC 135, named explicitly.
Decide the fluorine-free question against the oil requirement, because that is where the two constraints collide.
Agree the specimen and averaging rule in the specification rather than in the complaint.
Test post-wash at sample stage, and re-check the same tier on the bulk order.
Keep retained samples by lot, so a post-wash complaint can be traced to a specific roll.

Criteria Table: How to Tell Whether Three-Proof Wash Durability Was Actually Tested

Criterion	What Passing Looks Like	Common Failure
The three properties are reported separately	The report carries a water repellency result, an oil repellency grade and a stain repellency observation as three distinct items	One line reading "three-proof passed" covers all three, and no single property can be checked
The water repellency standard is named	The report states AATCC 22, ISO 4920 or GB/T 4745, matching the standard the buyer will judge against	The water repellency figure is quoted with no standard, so it cannot be compared with the buyer's reference test
Water repellency is given in the right unit	AATCC 22 results appear in points and ISO 4920 or GB/T 4745 results in grades, with the scale printed	A figure is quoted with no scale, so a points result and a grade result are read as the same thing
The oil repellency figure carries no water repellency standard	The oil result is stated as a grade on the grade scale, with no spray standard number attached	A spray rating standard is attached to an oil repellency figure, which misrepresents how it was judged
The oil result is presented as data, not as an attached standard	The oil grade is offered as a measured result, and the absence of an independent standard number in the testing menu is stated	A standard number is invented for the oil item so the report looks complete
The wash tier is stated with a count	The report states the exact tier, such as as-received, after 1–5 washes, after 6–10 washes, after 11–15 washes or after 20 or more washes	The report says "after wash" without a number, so the durability tier cannot be judged
The washing standard is named beside the count	The post-wash figure is tied to GB/T 8629, ISO 6330 or AATCC 135 on the same report	A wash count is written with no washing standard, and the candidate standards differ in mechanical action
The claim tier matches the tested tier	The tier named in the marketing or specification text is the tier that appears on the report	Data exist for one tier and the claim names a different one
The retention or absolute rule is agreed	The specification states whether the post-wash requirement is an absolute grade or a share of the as-received grade	No retention rule exists, so a post-wash figure cannot be judged as passing or failing
The specimen count and averaging rule are stated	The report shows how many specimens were tested and whether the figure is the average or the worst specimen	Only the average is printed, and the complaint turns out to be based on the worst specimen
The chosen chemistry matches the binding property	The specification names which of the three properties is binding, and the chemistry selected carries that one	A high oil grade is required alongside a fluorine-free finish, and the trade-off is only discovered after the bulk order
Post-wash data exist before bulk	The tier result exists at sample stage, and the same tier is re-checked on the bulk order	The tier is tested only on bulk, where a failure is expensive to correct

Three-Proof Finishing and Wash Durability: How Water, Oil and Stain Repellency Are Tested After Washing