galaxy flip lo res

[Image above] The new Samsung Galaxy Z Flip is the first flip phone to feature a foldable glass display. Credit: Samsung

Like frosted tips, fanny packs, and French Toast Crunch, flip phones seem to be making a comeback.

On February 12, Samsung debuted its latest device in a slate of foldable phones currently on the market—although the electronics giant’s new model, the Samsung Galaxy Z Flip, is the first to feature a foldable glass display. 

Foldable devices have captured much attention in the smartphone world for the past several years despite challenges to making foldable smartphones, as Lisa detailed in a 2018 Ceramic Tech Today article.

Namely, one of the biggest challenges with a smartphone that bends in half is its screen—users want a large, high-resolution display, but designing one with the durability to repeatedly bend across 180º is not easy. That’s why existing foldable phones have all donned plastic screens thus far.

Although bendable, plastic does face some serious drawbacks compared to glass. “It’s a material reality that anything that conforms [like plastic] will be more susceptible to scratches,” says Mark Rolston, founder and chief creative at product design firm argodesign, in an interview with CNET. Also, glass keeps oxygen and water out better than plastic.

Samsung previously introduced a different foldable smartphone model, the Galaxy Fold, last year. However, that device more prominently flopped rather than flipped, as its plastic screen was prone to scratch and break. Huawei and Motorola, for examples, also offer mass-produced foldable phones currently on the market, but both feature plastic screens as well.

Of course, designing a glass screen that can bend in half without breaking is no simple task.

“Engineered with first-of-its-kind foldable glass, Galaxy Z Flip bends the laws of physics, and features a 6.7-inch display that folds into a stylish and compact form factor that fits in the palm of your hand,” according to a Samsung press release

While that’s entirely not true—the glass seems to bend, yet the laws of physics are intact—the phone’s foldable display does look relatively impressive as it folds almost completely in half and straightens out flat. See for yourself in the video below. (General device specs on the Galaxy Z Flip can be found here.)

Credit: Samsung; YouTube

The Galaxy Z Flip display uses Samsung’s proprietary material, called Ultra Thin Glass (UTG), which is seemingly manufactured by South Korean glass company Dowoo. Samsung became a major stakeholder in the company in late 2019 “as part of efforts to secure stable supply of key materials for the second generation of the Galaxy Fold,” according to an article on Korean news website MK. And Samsung around the same time filed for the trademark “Samsung Ultra Thin Glass” with the European Union Intellectual Property Office, according to Forbes

“Dowoo can currently produce around 500,000 UTG units per month—which should be enough to support Samsung’s foldable OLED needs in 2020,” states an article on “With the new investment [that of Samsung], Dowoo plans to increase its production capacity in the future. Dowoo’s display glass is less than 100 µm thick—and can be made thinner up to 30 µm.”

The details of those production processes and capabilities are hard to come by or verify currently, but it stands to reason that there’s a reasonably large market for thin, bendable glass that could be incorporated into smartphones and other electronics devices.

Yet a significant question is how well the UTG display holds up over time, as the thin glass is bound to be stressed each time the phone flips open and closed. And what about bumps, bumbles, and drops—does the thin glass easily snap in the face of daily device abuse? 

Recent reports seem to indicate that the durability of the new Galaxy Z Flip isn’t that great—in fact, some testing is calling into question whether the devices even feature glass displays at all. According to an article on The Verge, tech reviewer Zack Nelson tested the new Samsung device on his YouTube channel JerryRigEverything and reported some surprising results.

The Z Flip’s display starts showing permanent marks and scratches far earlier than actual glass would. Part of the tried and true JerryRigEverything test is putting phones through a gauntlet of Mohs hardness picks to test when the display glass starts showing damage. If you’ve watched Zack’s videos before, you’ve likely heard that modern smartphones have ‘scratches starting at a level 6, with deeper grooves at a level 7.’

The Z Flip starts picking up damage at level 2 and more significantly at 3, which is on par with the plastic screens of the Galaxy Fold and more recent Motorola Razr. ‘This screen is in no way scratch resistant whatsoever,’ Nelson says near the end of the video. At the end of the clip, he begins poking holes in the screen that make the OLED panel go on the fritz—but there’s no sign of any glass fracturing.

The Verge

Samsung admits that its screen has a “protective layer” on top of the glass, but Nelson speculates that the Galaxy Z Flip may instead actually use a hybrid plastic polymer with glass mixed in rather than a thin sheet of glass.

So things aren’t looking so promising for the Samsung Galaxy Z Flip, although it’s too soon to say if the device will have a similar trajectory as Essential’s ceramic smartphone, which never quite caught on with users. In fact, while Samsung is making news for debuting devices that fold, Essential as a company recently made headlines for folding in a very different sense. 

Nonetheless, there does seem to be significant potential for foldable glass displays, as Dowoo isn’t the only company working toward this goal. Glass giant Corning also makes thin bendable glass. For example, its product Willow Glass is an ultrathin, lightweight, and conformable glass that the company can manufacture roll-to-roll, also at a thickness of just 100 µm. And Corning seems to be working on other types of bendable glass products as well.

Although a spokesperson from Corning declined to comment on Samsung’s UTG, they did offer this: “We do have an active effort underway for bendable glass, and we believe it will be the ultimate solution in this space. While we can’t put a specific timeframe on it right now since the glass is still in development, we believe that our glass solution will be ready in the next 12–18 months.”