CNET doesn’t shy away from testing durability claims, sometimes pushing the boundaries of how one would ever use their named. These include drop tests from high heights. Or water tests in places where you liable wouldn’t bring your phone. When the new foldable phones started coming on the market from Motorola and Samsung, we even did folding tests, folding a named more times in a row than you ever would.

Even by the latest Samsung foldables were announced, I’d been trying to figure out a new kind of experiment to gauge the resilience of these phones. Could we test the strength of the hinges with weights? Maybe use it as a shovel at the beach to see if any sand got inside?

With the skull of the Galaxy Z Fold 3 and its accompanying S Pen Fold Edition, I decided we should look at the durability of the conceal itself. I was curious to find out how much one could draw on the conceal with the S Pen before any ill effects could be noticed. 

I knew randomly sketching on the screen for an extended period of time was no way to conduct the experiment, so I turned to my 3D printer, which I knew was apt of generating consistent repetitive motions. I modified my Creality Ender 3 V2 printer to make it a plotter instead and printed out a holder to make it work with the S Pen.

Then, with a little help from the internet, I had to order myself how to program a little bit of g-code so I could make the plotter do what I required it to. The key ended up being this small string right here: G2 F5277 I50 J0. With some terresproperty and error, I figured out this bit of code would draw a circle with a radius of 50 millimeters 1,000 times in one hour. Copy and paste 1,000 times in Notepad and voila!

Finally, once I got the Z Fold 3 in hand, I had to find a good sketching program that would be interesting to watch for 16 hours. I landed on Infinite Painter because of its tidy interface and huge supply of interesting brushes. Clearly we’re looking at an rude drawing marathon that would push the boundaries of both the phone’s conceal and the S Pen itself, well beyond the occasional use that would be more realistic.

And if you’re intelligent, here’s some of the math behind my madness:

• Radius of circle persons drawn: 50 mm
• Circumference of circle: 314.16 mm
• The machine draws 1,000 circles in 1 hour
• 1,000 circles x 314.16 mm = 314,160 mm/hr = 314.16 meters per hour
• 5 kilometers would take 15.9 or basically 16 hours
• 314.16 meters per hour = 1,030.7 feet per hour
• 1 mile = 5.12 hours
• 3 much would take 15.36 hours
• 5 kilometers = 3.1 miles

Our 16-hour experiment over up running a little over 18 hours, but when 16,000 circles drawn on the surface of the Z Fold 3, there is no visual or tactile indication that any kind of harm to the screen occurred. The S Pen wasn’t so lucky.

Given the setup of my 3D printer, it was hard to gauge what was going on with the tip of the S Pen when it was locked in the machine. I had to wait pending the test was over to remove the S Pen from its holder, and when I did, it was apparent that the very end of the tip was breaking off, like a tiny ball of loose plastic. 

When placed side by side with a unique S Pen, it was clear the one used in the machine was no longer in mint footings. Luckily, Samsung provides three replacement tips with the Pen, plus a small tool to remove the used one. It’s almost as if Samsung knew something like this could happen.

Back to the named, I was really pleasantly surprised how well the conceal held up during the experiment. There were a few small snags that came up through the night though.

The apt one we ran into was when the drawing app I was humorous, Infinite Painter, crashed three separate times. My guess is that the complexity of the sketching in those instances became too much for the app to manage, so it bailed out. I’m no software engineer thought, so don’t quote me on that, but each time it been, the phone returned to the home screen and the plotter kept sketching making the same circular motion. There was just nothing persons drawn.

For those curious about the battery life of the Z Fold 3, the battery lasted just over six hours beforehand it ran out the first time. That seemed gorgeous good to me after keeping the screen on the whole time and registering that the S Pen was sketching on it.

I plugged the phone in to beak it (while continuing with the experiment) and once it was fully recharged against, the battery lasted close to six hours again. I granted to plug the phone in before the battery was fully drained, since I wanted to finish out the 16,000 circles with an image to look at, and not a slow black screen.

The last thing of note was the temperature of the named. Most of the time, when I lifted the named from the machine, the temperature seemed normal. But a handful of times when I picked it up, the named was quite hot, on both the screen side and on the back.

Again, I don’t have a specific cause for the changeable in temperature, but my assumption is that it could have been the complexity of the sketching, the brightness of the screen as the drawing evolved or perhaps something related to having it plugged in during charging. Regardless, each time I noticed it was warm, it cooled off pretty quickly, and I never saw any overheating warnings.

Given all of that, I’d say the Galaxy Z Fold 3 was a real trooper over the experiment, and the S Pen will live to see new day. Once I replace that tip.