Custom PU Slide Sandals: How to Plan Flex and Abrasion Testing

Who this article is for

This article is for footwear brands, private-label developers, importers and wholesalers who want clearer durability requirements before approving custom PU slide sandals for bulk production.

It explains how to prepare a test brief. It does not set universal cycle counts, abrasion limits or service-life promises.

Separate the two performance questions

Flexing testing repeatedly bends a whole shoe or a component to observe damage associated with repeated movement. Abrasion testing evaluates material loss or resistance to wear under a defined method.

For a custom PU slide, the buyer should ask two separate questions:

1. Does the product construction tolerate the agreed repeated-flexing test without the defined failure?
2. Does the outsole material meet the agreed abrasion requirement under the selected method?

Combining the two into one phrase such as durable sole makes the requirement difficult to test and approve.

Choose the flexing method before discussing cycles

ISO 24266:2020 specifies two methods for determining the flexing durability of whole shoes. The ISO abstract states that the two methods may not give comparable results and that method selection depends on agreement between the relevant parties or on the product standard that references the method. [1]

The same standard also identifies applicability limits relating to heel height, sole thickness in the flexing area and flexing angle. [1]

This matters for thick custom PU slides. A buyer should not copy a cycle number from another product without first confirming that the specimen and selected method are suitable.

The flex brief should identify:

• whole-shoe or component test;
• test method and edition;
• model and size;
• flexing location;
• conditioning;
• number of cycles or inspection intervals from the approved requirement;
• failure criteria;
• reporting photographs and specimen identification.

Define what counts as flex failure

Before the test, agree on the observations that matter. Depending on the construction, these may include:

• visible cracks in the sole or upper;
• separation at a joint;
• tearing around an attachment point;
• permanent deformation;
• surface splitting;
• a functional change that prevents normal use;
• no defined damage at the agreed inspection point.

The report should state the location and type of damage. A single pass or fail line is less useful when the development team needs to understand which part changed.

Test outsole abrasion as a separate material property

ISO 20871:2018 specifies a method for determining outsole abrasion resistance, irrespective of outsole material. [2]

An abrasion test is not a full prediction of how long a sandal will last in every market. Actual wear can vary with user weight, walking pattern, surface, frequency, environment and product geometry.

The abrasion brief should identify:

• outsole material or compound reference;
• color and production batch where relevant;
• specimen preparation;
• agreed test method and edition;
• result unit required by the method;
• acceptance source;
• comparison sample if used;
• retest rule after compound or process changes.

Keep sample conditioning consistent

ISO 18454:2018 defines standard atmospheres for conditioning and testing footwear and footwear components. [3]

If sample rounds are conditioned differently, their results may not be directly comparable. The buyer should make sure the laboratory report identifies the agreed conditions and any deviation.

For aged or environmentally conditioned specimens, keep the preconditioning step separate from the flex or abrasion method and record both.

Set acceptance criteria from a justified source

The test method tells the laboratory how to conduct the measurement. The acceptance requirement must come from an applicable source, such as:

• a retailer or customer specification;
• a destination-market requirement;
• the brand’s internal standard;
• a product standard;
• an approved reference product and agreed comparison rule.

If the project does not yet have an approved limit, mark it as pending confirmation. Do not invent a durability promise from a machine cycle count.

Link every result to the correct sample version

Record the following with each test:

• model and size;
• outsole geometry and tread version;
• material or compound reference;
• sample date and production stage;
• color where material formulation may differ;
• mold or construction revision;
• test report number;
• approval decision and approver.

This helps prevent a result from an earlier sample from being applied to a changed bulk-production version.

Practical test-plan checklist

Before sending specimens, confirm:

• flex and abrasion are listed as separate checks;
• each check has an agreed method and edition;
• the product fits the method’s scope;
• specimen model, size and material version are recorded;
• conditioning is defined;
• inspection points and failure criteria are approved;
• acceptance limits have a documented source;
• report photographs and raw results are requested;
• retest triggers are defined.

FAQ

Is a high flex-cycle number proof of long service life?

No. It is a result under a particular method and condition. Service life also depends on use, environment, construction and other material properties.

Can abrasion resistance replace a flex test?

No. Abrasion measures a wear-related material response, while flexing evaluates repeated bending under a defined method.

Should the whole slide or only the sole be tested?

That depends on the question. Whole-shoe flexing can evaluate the assembled construction, while outsole abrasion focuses on the soling material. The brief should state the test object.

When should a buyer consider retesting?

Review retesting after changes to the compound, outsole geometry, thickness, attachment method, mold, supplier, processing conditions or other factors covered by the approved specification.

Sources

1. ISO 24266:2020, Footwear — Test methods for whole shoe — Flexing durability: https://www.iso.org/standard/78251.html
2. ISO 20871:2018, Footwear — Test methods for outsoles — Abrasion resistance: https://www.iso.org/standard/63230.html
3. ISO 18454:2018, Footwear — Standard atmospheres for conditioning and testing of footwear and components for footwear: https://www.iso.org/standard/63229.html

Discuss your durability brief

Henghao Slide Sandals Factory supports custom PU slide development for brand and wholesale projects. Appropriate test methods, limits and samples should be agreed for the specific construction and destination market.

For broader sourcing guidance, visit the Custom PU Slide Sandals Buyer Help Center: https://www.henghaoshoes.com/custom-pu-slide-sandals-buyer-help-center/

To discuss a project-specific test plan, contact Henghao: https://www.henghaoshoes.com/contact/