iPhone Duo back glass and frame: materials, care and repair

iPhone Duo pairs a grade 5 titanium enclosure with a Ceramic Shield back, according to Apple. Here is what that means, what independent tests found, and what to do if the back cracks.

What Apple says the back and frame are made of

Apple's launch announcement says iPhone Duo is "crafted from grade 5 titanium for incredible strength," with a mirror-polished finish. Apple's Identify your iPhone model support document also lists a grade 5 titanium enclosure and hinge cover.

The iPhone Duo spec page adds that the enclosure is 85% recycled titanium, while the internal structural frame is 100% recycled aluminum. The 3D-printed hinge cover is 100% recycled titanium, and Apple's announcement says it gets a micro-blasted finish that contrasts with the polished frame.

On the back, the spec page lists a Ceramic Shield back, while Ceramic Shield 2 covers the front, which Apple's announcement identifies as the outer display. Apple says Ceramic Shield 2 has 3x better scratch resistance than the previous generation. Apple hasn't given a comparable figure for the back, and the spec page doesn't describe the back's finish. Apple also says antenna splits with ceramic fiber inserts add rigidity to the frame.

What durability tests found

The published scratch and bend results cover the screens and hinge, not the back. MacRumors' write-up of JerryRigEverything's video reports that the Ceramic Shield 2 outer display scratched at level 7 on the Mohs scale and the inner display at level 2. It doesn't report a result for the back glass. Its bend test left a permanent line across the inner display; the JerryRigEverything video summary has the details.

Drop tests say more about the back. iPhone in Canada reports that in PhoneBuff's robotic drop test, a 1-meter drop onto the back cracked the back glass on both iPhone Duo and iPhone 18 Pro Max, with the damage spreading wider on iPhone Duo.

In the same test, corner drops left only hard-to-see scuffs on the iPhone Duo titanium, while the iPhone 18 Pro Max's aluminum lost paint and dented.

9to5Mac reports that iFixit's teardown found one of iPhone Duo's two batteries under the back glass and the other under the outer display. More in the teardown roundup and the durability tests roundup.

How Apple says to clean the back and frame

Apple's iPhone cleaning guide says to unplug all cables, turn the phone off, and wipe it with a soft, slightly damp, lint-free cloth, such as a lens cloth. To disinfect the exterior, Apple allows gentle wiping with a 70% isopropyl alcohol wipe, a 75% ethyl alcohol wipe, or Clorox Disinfecting Wipes.

Apple says to avoid bleach, hydrogen peroxide and compressed air, and to keep moisture out of openings. Apple also warns that cleaning products and abrasive materials can wear down the oleophobic coating and scratch the phone.

That coating covers the back as well as the front on iPhone 8 and later, Apple says, and it wears down with normal use.

One useful note: Apple says contact with denim or other pocket items can leave material transfer that looks like a scratch but can usually be removed, and the guide lists iPhone Duo among the models this applies to.

For the hinge, Apple's water and dust resistance document says to make sure the hinge is clean before unfolding iPhone Duo, without cleaning products or compressed air. More in hinge care and outer display care.

If the back glass cracks or the frame is damaged

Leave the repair to Apple or an authorized provider. Apple's back glass repair procedure is written for technicians and uses specialist heating and pressing equipment.

Apple's iPhone Duo parts list does name the back glass as an orderable part, in Star White and Night Sky versions. iFixit's teardown found one of the two batteries under the back glass, so get a cracked back looked at by Apple or an authorized provider.

Apple's iPhone repair page prices back glass damage on its own and also lists a combined outer display and back glass repair. See the current fees for back glass and outer display plus back glass, or run the numbers in the repair calculator.

The same Apple page says AppleCare covers unlimited repairs for drops and spills, with a service fee. More in whether AppleCare+ is worth it and how to make a claim.

A dented frame near the hinge is a different case. Apple's hinge troubleshooting guide lists enclosure damage that affects the hinge among hinge issues, and says there aren't diagnostics or software remedies for hinge issues, so that's a job for Apple service.

Bottom line

In PhoneBuff's test, the titanium corners held up better than the back glass. A case that covers the back and corners is the cheap fix; start with the best iPhone Duo cases.

Has your iPhone Duo's back or frame picked up damage yet, and how did the repair go?