As hundreds of workers spill out of the canteen after lunch, the young women's bright pink uniform jumpers stand out against the grey sky, the hulking grey factory buildings and the thick grey coal dust under their feet.
They are back at work at Foxconn Technology Group's plant in Taiyuan, and some of them wonder how nothing has changed after it was rocked by one of China's worst incidents of labour unrest in years.
People's Armed Police on Tuesday continued patrolling the Foxconn campus in groups of 12. The car park of mdo – an upmarket shopping mall across the street from the south-west corner of the factory campus – was blocked off and filled with more than 30 trucks, 15 vans and several buses carrying PAP in a show of force.
Forty people were hospitalized and several arrested after a riot involving more than 2,000 on Sunday night, according to Foxconn.
The company, also known under the name of Hon Hai Precision, its Taiwan-listed flagship, makes many of the world's electronics gadgets, including most of Apple's iPhones and iPads, in what may well be the world's biggest manufacturing empire.
A series of suicides among Foxconn staff in 2009 and 2010 dragged this gargantuan manufacturing machine to public attention.
They threw a spotlight on the more than one million mostly very young men and women who spend their days and nights caught between the stress of Foxconn's manufacturing lines and the boredom and loneliness of its dormitories in factory towns housing up to 400,000.
In reaction, the company raised wages drastically, started offering counselling services and promised to reduce overtime.
But workers and external analysts say that, while the reforms have helped, the scale of the Foxconn manufacturing operation and the overall conditions in the industry mean that the old problems are bound to keep coming back.
"The nature of the Foxconn workers' job – the pressure, the monotony, the tediousness – has not changed," says Liu Linping, a professor at the school of social sciences at Nanjing university.
"Therefore it is unavoidable that incidents like this [can] happen from time to time."
That was less of an issue a decade or two ago, when Chinese migrant workers were more desperate for a manufacturing job and more willing to sacrifice their youth to accumulate some savings.
The women and men in their teens and 20s now working on the production lines are less patient.
Workers at the Taiyuan plant say that, while Sunday's riot started as a brawl between a few workers and factory guards, throngs of others quickly joined in because of pent-up anger and frustration.
"Within half an hour, people were screaming to smash the windows of the supermarket and the handset mall on the shopping street on the factory campus," says Liu Senqi, an employee in the factory's human resources department who watched the riot from his dormitory window.
Once there was violence, the plant, which employs close to 80,000 people, proved far too big to bring under control.
"Every inch of ground was covered with people; it was a black mass of bodies below me. When the police arrived after an hour, they could just stand there and watch," says Mr. Liu.
One main source of anger was that the company "borrowed" large groups of workers from its plants in Shenzhen and Zhengzhou because it is facing a constant labour shortage at the Taiyuan factory.
Mr. Liu, who was transferred from Shenzhen in early June, says he was initially told he was to work in Taiyuan for about four months, but that the company is now being vague about when he can go back. Another cause for disquiet was the lack of overtime during the forthcoming National Day holiday. Many workers say they have been counting on working next week, as overtime during national holidays means threefold wages.
Although Foxconn's basic monthly pay of Rmb1,800 ($285 U.S.) for line workers is much higher than the minimum wage in Taiyuan, staff say the overtime, which can take their pay to double that figure, is what makes the monotony of the job bearable.
"I feel a bit … hungover now," says Chang Guixiang, a 22-year-old female worker from a small town a few hundred kilometres from the factory.
Like dozens of others on the night shift, she has nothing to do during the day. Leaning against a wall opposite Number 3 South Gate of the huge factory compound, they watch workmen sweep up glass from broken windows and smashed bus windscreens, carry off a steel gate pushed over by the crowd and scrape at a big scorched stain on the wall of the police post.
Another staff member, who asked not to be named, says many felt inspired by the anti-Japanese protests across the country earlier this month.
"It is so rare in China that you can demonstrate when you're unhappy about something. It felt like the right moment," he says.