Technology journalist Joanna Stern ran an opening-and-closing test of more than 30,000 cycles on Apple's foldable smartphone, the iPhone Duo, and published the results on October 21, 2026. Even after the test, she said, the hinge felt almost the same as it did on day one. The result adds hands-on evidence to the durability design Apple described in September. On the 22nd, however, a report emerged that the display near the crease deforms under finger pressure. A hinge that survives repeated folding and a screen that withstands localized pressure are separate questions, so assessing the iPhone Duo's durability requires keeping each test's conditions and results distinct.
Hinge feel nearly unchanged after 32,640 folds
In her iPhone Duo review on her outlet The New Things, Stern said she used a custom-built rig to fold the phone more than 32,000 times. A review unit was mounted in the machine, which kept opening and closing it automatically, even overnight. The public portion of the article outlines the test, while the detailed findings are in a paid section.
According to a description quoted from the article, the test ran over four nights and totaled 32,640 folds. Stern compared the force needed to open the hinge before and after, using a calibrated measuring instrument. The force required had increased slightly, but she judged that in everyday use it felt "almost the same as on day one." In other words, under these test conditions, no change such as an obvious loosening of the hinge was reported after more than 30,000 folds.
The rig did not, however, close the iPhone Duo fully on every cycle. That differs from real-world use, such as closing the device completely, slipping it into a pocket, and opening it again later. And a test that folds the phone repeatedly over a short period cannot reproduce all the wear and aging that come with long-term use, so it is hard to convert 32,640 folds directly into years of everyday use.
What the test confirmed is that, under specific conditions, the hinge's feel was largely maintained after repeated folding. It was not a run-to-failure test measuring product lifespan, nor does it indicate the failure rate of devices on sale. Even so, it is meaningful to have results from repeated operation of a real unit to set against Apple's description of the hinge design.
Apple's display structure aims to make the crease less visible
According to the specifications Apple announced on September 9, the iPhone Duo has a 7.6-inch inner display and a 5.4-inch outer display. The inner display uses a Nano-texture finish that reduces light reflections and glare, making the crease in the middle of the screen less noticeable. However, this is a technology for reducing the crease's visibility; it does not mean the structural unevenness at the center of the display has disappeared entirely.
Making the crease less conspicuous depends not only on the display's surface treatment but also on support from the hinge. Apple says the iPhone Duo's hinge is made up of more than 100 parts, controlling the folding motion and keeping the center of the display flat when the device is open. The design reduces reflections on the screen surface while the internal mechanism supports the part that bends.
The display itself also has features meant to withstand repeated folding. Apple explains that high-strength glass is placed above and below the foldable panel, and a dedicated adhesive lets the layers slide against each other like the pages of a book. This is intended to distribute the force on each layer when the phone folds and keep stress from concentrating in one spot. The surface is further protected by a scratch-resistant coating and a polymer cover layer, and a titanium plate sits beneath the display.
Rather than bending a single rigid plate, the structure lets multiple layers move independently to reduce the load from folding. But such a design mainly anticipates the forces generated while opening and closing; it does not guarantee strength against a finger pressing on a single point of the screen. Durability against folding and resistance to localized pressure need to be evaluated separately.
Indeed, HotHardware reported on October 22 on a video in which the surface deforms under relatively light pressure when a finger is run along the crease area. The outlet cited a video posted on Weibo, but the original sits behind an authentication page and could not be checked directly, so how much force was actually applied is unknown. It is also unclear whether the deformation returned to normal after the finger was lifted or left a mark. This report alone therefore cannot establish that the display suffered permanent damage, and there is not enough evidence to pin the problem on a particular material or structure.
Hinge durability and screen strength are separate measures
What matters in sorting through this information is that the hinge fold test, the visibility of the crease, and deformation when the screen is pressed each measure a different property. Stern's test focused on how the hinge felt after repeated folding. Apple's Nano-texture finish is primarily a technology for reducing light reflections, and the video HotHardware described deals with how the screen deforms under localized pressure. It would not be appropriate to compare these as results of the same durability test.
The table below summarizes what each source confirms and what cannot yet be determined.
| Item evaluated | What can be confirmed now | What cannot yet be determined |
|---|---|---|
| Hinge durability | Report that, after 32,640 folds, the feel in everyday use was almost unchanged | Durability and lifespan over long-term use, including full-closing motions |
| Crease visibility | Apple uses a reflection-reducing surface treatment and a structure that supports the center of the screen | Whether the crease stays inconspicuous under the same lighting and angles after long-term use |
| Resistance to pressing on the screen | Report that the surface deformed when a finger was run along the crease area | The amount of force applied, whether the deformation recovers, and whether there is permanent damage |
The table organizes Apple's official design explanation, Stern's hands-on review, and the report on the video HotHardware covered by the aspect each addresses. It does not rank the results; it separates what the current information shows from what it doesn't.
Seen this way, there is no contradiction between the absence of reported hinge loosening in the fold test and concerns about deformation when the display is pressed. That the hinge withstood repeated motion does not guarantee the strength of the whole screen. Conversely, even if part of the screen is seen deforming under pressure, that alone does not mean there is a problem with hinge durability. As for the crease, the bumps felt by touch differ from how visible the line is depending on how light hits it, so each should be evaluated separately.
Future testing will focus on full closing and changes to the screen
The fact that the rig did not fully close the device in this test is one point to watch in future evaluations. Repeating folds that include fully closing the phone, and measuring the force needed to move the hinge before and after by the same method, would allow an assessment closer to real-world conditions. Beyond simply increasing the number of folds, it is also important to clarify how far the device opens and closes in each motion and at what speed. Without matching test conditions, it is hard to compare different results by count alone.
The display likewise needs separate tests for how visible the crease is and for physical deformation. To compare crease visibility, one approach would be to fix the lighting and viewing angle and record the screen's condition before and after use. To examine resistance to pressing, it is important to keep the position and load of the applied force constant and to check whether the screen returns to its original state once the pressure is removed. Such tests would make it possible to distinguish differences in appearance caused by light reflection, temporary deformation, and permanent damage.
Apple's design explanation in September gave no guaranteed fold count equivalent to the product's lifespan. Stern's test is an interesting result, showing that the hinge feel was largely maintained through more than 30,000 repeated folds, but it is not enough to draw conclusions about long-term durability. After the October 23 launch, hands-on testing will matter, including fold tests that involve fully closing the device and continued comparisons of the crease and surface condition of the screen. As such data accumulates, buyers will be able to judge the iPhone Duo's durability under conditions close to their own use, rather than relying only on a fold count.