If footwear screen printing ink cracks during flexing, start with the actual material, the affected print layer and the test conditions. Normal bending, a low-temperature flex failure and a raised clear print tested before conditioning is complete need different checks. Review water-based footwear inks, TPU printing inks or raised-print systems against the full layer construction, required appearance and specified test. Share when cracking first appears, the layer sequence and the drying and conditioning records so our factory team can plan a comparison trial before recommending another ink.
Identify the cracking pattern
| Failure pattern | Review | Record for comparison |
|---|---|---|
| Cracking during normal flexing | The complete print construction, layer build and material movement. | The affected layer, conditioning and test method. |
| Failure only in a low-temperature test | The ink candidate against the actual substrate and specified cold-flex requirement. | Temperature, conditioning, cycles and acceptance criterion. |
| Rubber-particle print changes during a run | Powder loading and whether the mixture remains uniform. | Mixing records and samples from the beginning and end of the run. |
| Raised clear print fails flex testing | The clear system, specified hardener, layer build and final conditioning. | Product models, mixing and actual drying/curing records. |
If layers peel apart rather than crack through the print, also use the adhesion and delamination guide.
Three flex problems from our factory case records
Rubber-particle water-based print cracking
A Yunrui case connected poor flex performance with excessive rubber-powder loading and settling that changed the mixture during printing. The proposed review covered loading, consistent mixing and evaluation of a more flexible clear system such as HC-7.
Trial focus: compare samples across the print run, not only the first acceptable piece. HC-7 is a case-specific candidate, subject to the actual material and finish requirements.
Low-temperature failure on a special deep-textured material
A special-material case recorded low-temperature flex and alkali-test problems with the existing solvent-based construction. It identified 37H and a suitable water-based approach for evaluation, and called for repeated testing on both cut pieces and finished shoes.
Trial focus: agree the actual temperature and test criteria. A product suitable for one TPU or mesh construction is not automatically suitable for another cold-flex requirement.
Raised water-based clear print failing flex testing
Another case identified hardener proportion, insufficient conditioning and the flexibility of the selected clear system as factors to review.
Trial focus: separate drying between layers from the final conditioning required before testing. Confirm conditions against the exact product instructions instead of copying another case’s oven settings.
Technical basis: Yunrui factory presentation, flex cases 2, 3 and 4. Candidate systems and process observations require validation on the customer construction.
Select footwear screen printing ink for a flex trial
Match the candidate to both the shoe material and the layer that cracks. Water-based footwear screen printing ink, TPU printing ink and high-density printing systems are different product routes. A colour ink, a raised-print base and a clear finish also perform different jobs in the print construction; confirm the full product name and matching TDS before comparing candidates.
For a low-temperature flex requirement, compare the complete printed construction at the specified temperature, conditioning, cycles and acceptance criterion. First make the existing mixing, application and conditioning repeatable. If it still fails the target test, discuss custom formulation and material assessment. A successful case on another material does not establish performance on yours.
Build a useful flex trial brief
- Material and finish, including an unprinted sample if available.
- Basecoat, colour, raised layer and finish, with any powder additions.
- Actual mixing, layer build and conditioning records.
- Test method, temperature, cycles, acceptance criterion and where cracks appear.
- Whether the issue is reproduced on cut pieces, finished shoes or both.
Compare the original construction and the agreed candidate under the same conditions. Confirm repeatability and relevant downstream operations before a production change.
Common questions
Is water-based ink always more flexible?
No universal choice follows from the ink category alone. The factory case identifies a water-based route as an option for a particular material. The formulation, layer construction, conditioning and target test still need evaluation.
Can you guarantee a cold-flex pass from a photo?
A photo can show the failure pattern but cannot establish test performance. Share the material, full print construction and test conditions so that an appropriate sample evaluation can be agreed.
Do you need a finished shoe or an upper sample?
Start by describing where the problem occurs. Cut pieces may help assess the print, while a failure after forming may require the finished construction. Confirm the evaluation and receiving instructions before shipping.
Discuss a flex failure or a new performance target
Start with your material, cracking pattern and test requirement. Product selection, development scope and sample arrangements are confirmed with our factory team.
When does cracking first appear?
Record whether cracking appears after drying, forming or the specified flex test. Include the material, print layer sequence, test temperature and the acceptance criteria if available.
A photo, material name and defect stage are enough to begin the discussion. Trial samples are free; the customer pays postage.
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