Testing standard
Footwear — Test methods for whole shoe — Upper sole adhesion
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
ISO 17708 measures the resistance to separation of the upper from the outsole on a finished shoe. It also covers separation between adjacent layers of the outsole and tear failure of the upper or the sole, and it defines ageing conditions that can be used for production control.
Finished shoes, aged to defined conditions where the specification requires it and then conditioned, have the sole cut into a strip of defined width at the position to be tested. The separation is started at one end to create a tab on each side, the shoe is supported so that the peel front will travel along the bond line, and the upper and the sole strip are gripped separately and drawn apart at a constant rate. The force is recorded throughout and divided by the strip width, and the way the specimen gave way is classified.
Whether the sole will stay on — measured on the shoe the factory actually made, over the last it was made on. That is the distinction from a bonded-coupon test, and it is the whole point of the method. A coupon establishes that an adhesive is capable of a given strength under controlled conditions; this establishes whether the roughing, priming, cement application and press time used on the day achieved it on a curved, three-dimensional article. Everything that goes wrong in footwear production lives in the gap between those two, and only a whole-shoe test can see into it.
The bond can let go, a sole layer can split, or the upper or sole can tear. Only the first is an adhesion figure.
This is a whole-shoe test, not a coupon test. It measures the bond the factory actually made, on the last it was made over, with the adhesive it was made with.
Separation force divided by the width of the strip peeled
Force per unit width, so the width has to be defined and measured. A whole-sole force divided by nothing is not comparable with anything.
Bond separation, sole layer separation, or material tear
Reported with the force. Without it the number cannot be acted on, because two of the three modes are not adhesion results at all.
Pneumatic vice action grips hold each arm of the T at a constant pressure through a long peel, which a screw grip does not — a peel test runs for hundreds of millimetres and a slipping grip corrupts the whole trace.
SpecificationsLow forces and long, controlled travel — separation typically runs from tens to a few hundred newtons and continues for the length of the bond. The load cell is chosen for that range rather than for the frame. What the set-up needs more than capacity is a way of holding an irregular article so the bond line stays presented to the grips throughout, and grips that hold a flexible upper and a rubber sole strip without cutting either. Ageing to the specified conditions needs an oven or chamber alongside.
Reporting a force without the failure mode, when two of the three possible modes are not adhesion results at all — a torn upper describes the upper's tear strength, and a sole layer separation describes the sole unit's internal construction, pointing at a different supplier and a different process. Letting the shoe move so the peel angle drifts. Testing fresh shoes only, when the standard supplies ageing conditions precisely because an adhesive that bonds well may not stay bonded through a warehouse and a container.
| ISO 17708 | ISO 8510-2 / ISO 11339 | |
|---|---|---|
| Specimen | A finished shoe | A flat bonded coupon |
| Measures | The bond the factory made | The adhesive itself |
| Geometry | Curved, as manufactured | Flat and controlled |
| Answers | Will this shoe come apart? | How good is this adhesive? |
A coupon test tells you the adhesive is capable; this tells you the factory achieved it. Surface preparation, roughing, primer and press time all live in the difference, and only a whole-shoe test sees them.
It is the ISO whole-shoe test for upper-to-sole adhesion. It determines the resistance to separation of the upper from the outsole, and also covers separation between adjacent layers of the outsole and tear failure of the upper or the sole. It applies to all types of footwear — cemented, vulcanised, injection moulded — where the upper is continuously assembled, which is to say a closed shoe. The current edition is ISO 17708:2018.
Because they answer different questions. A coupon test establishes that the adhesive is capable of a given bond strength under controlled conditions. A whole-shoe test establishes whether the factory achieved it on a curved last, with the roughing, priming, cement application and press time actually used that day. Everything that goes wrong in production lives in the gap between those two, and only the whole-shoe test can see it.
That the bond is stronger than the material — commercially the best possible outcome, and not an adhesion measurement. It should be recorded as a material failure rather than averaged in as an adhesion value, because the number obtained describes the upper's tear strength, not the bond. A specification usually treats it as a pass, but the distinction has to be visible in the report.
A failure between adjacent layers within the outsole unit itself, rather than at the upper. It is a construction problem in the sole — how the midsole and outsole were bonded or moulded together — and points at a different supplier and a different process from an upper-bond failure. Reporting it as an adhesion result would send a factory to fix the wrong thing entirely.
Because an adhesive that bonds well is not necessarily an adhesive that stays bonded. Heat, humidity and time can weaken a bond that tested perfectly when fresh, and footwear sits in warehouses and containers before it reaches a customer. Ageing to defined conditions before testing catches that, which is why the standard offers it as a production control tool rather than an optional extra.
So that the force can be divided by a width and compared with something. A whole sole peels unevenly — the bond area is wide, curved and varies in preparation along its length — so the force fluctuates in ways that have nothing to do with the adhesive. A strip of defined width gives a force per unit width, which is the quantity a specification is written against.
That it is not flat. A coupon peels in a plane; a shoe curves in every direction, so unless it is supported the peel front wanders round the shape of the last and the angle changes as the test runs. Since peel force depends on angle, that turns a measurement into an average over a geometry that drifted. Supporting the shoe so the separation front travels along the bond line is the practical heart of the method.
Dak verifies against whichever standard the method names, and where a class applies our frames sit a class tighter than it asks.
| The method asks for | Dak supplies | |
|---|---|---|
| Capacity | Low — upper to sole separation typically runs from tens to a few hundred newtons | Load cells from 1 kg to 60 ton on the Series 7200, and 0.5 to 100 kN on the Series 9000 |
| Force accuracy | Class 1 over the working range | ISO 7500-1 Class 0.5, verified to ASTM E4, DIN 51221 and BS 1610 |
| Gripping | Grips taking the upper and the sole separately, with the shoe supported so the peel front stays where it is meant to be | Our peel and adhesion fixtures, built to the specimen |
| Environment | 23 ± 2 °C standard laboratory atmosphere | 3009 series chambers, −150 °C to +400 °C — temperature only |
This page describes the method as practised. The governing text is the current edition from the issuing body. Tell us what you are testing and we will answer with the machine, the fixture and a quotation.
