A section of the Potala Palace in Southwest China's Xizang Autonomous Region Photos: Chen Xi/GT

Every autumn, as the fierce summer sun over the Xizang Autonomous Region softens to a gentle glow and the monsoon rains retreat, the iconic white walls of the Potala Palace in Lhasa begin to look a little weathered. It is then that a unique call goes out through the buzz of social media. "I traveled 3,000 kilometers to be a volunteer wall-painter at the Potala Palace… finally realized a dream I've had for four or five years…" reads a typical post on Chinese social media Xiaohongshu, where the hashtag "I'm painting the Potala Palace" recently began trending. What unfolds next is a captivating spectacle of community, tradition, and scientific ingenuity that gives the 1,300-year-old UNESCO World Heritage site its annual "facelift."

The scene at dawn is something out of a reverent dream. By 7 am, the vast square in front of the palace is still empty, the city of Lhasa barely stirring under hazy, pre-dawn light. But a crowd is already gathering, clutching buckets and brushes. They are a vibrant mix of local Tibetans who make the pilgrimage from distant cities like Qamdo and Nagqu, curious domestic tourists whose Lhasa trip serendipitously coincided with the event, and some other volunteers like the young man whose video diary charmed millions online. United by a shared sense of purpose, they spend the warm autumn days splashing, brushing, and laughing, their faces and clothes speckled with paint, participating in what many fondly call a "sweet" painting ceremony.

In fact, this painting job is a centuries-old tradition, a timed preservation ritual that takes place after the harvest, during an auspicious month of the Tibetan calendar, and must be completed before the 22nd day of its ninth month. The timing is critical: The harsh winter freeze has yet to arrive, and the summer rains have passed, providing a perfect window for the paint to dry and set, according to a report by tibet.cn.

More than just paint

The most enchanting part of this tradition lies in the paint itself. The materials read more like a kitchen recipe. The base is a special white clay, or kaolin, but the magic is in the additives, including fresh milk, sugar, honey, and even a sprinkle of precious saffron.

Bianba Qiongda, head of the cultural relics protection office of the Potala Palace Administration Division, told the Global Times that this unique formula is a masterpiece of preventive conservation.

"These natural ingredients create an eco-friendly coating that not only maintains the palace's vibrant colors but also forms a durable protective film on the wall surface," she explains. This organic layer is remarkably effective at shielding the ancient walls from the extreme elements at high altitude, the intense ultraviolet radiation, the battering winds, and the erosive rain and snow.

Bianba Qiongda explained that the Potala Palace is adorned in four distinct colors - white, red, yellow, and black - with each serving a specific climatic purpose. The dominant white color acts as a reflector, bestowing a "warm in winter and cool in summer" quality upon the massive structure by deflecting the strong sunlight. The red and black sections, strategically placed, absorb light and heat, while the yellow accents aid in dissipating heat.

"For a millennium-old structure, this color palette is far more than just majestic decoration, but a vital tool for self-preservation," she said.

The 'milk wall' myth

As the painting project commences, the palace walls become a canvas of human endeavor. Some volunteers work from the ground, while the professionals scale the formidable heights with the agility of seasoned climbers.

"We have a team of professional, trained personnel who perform the splashing work while suspended mid-air," Dasang, deputy head of the maintenance office of the Potala Palace Administration Division told the Global Times.

Down below, a festive, communal atmosphere prevails. It is here that a charming, if slightly messy, myth persists: the legend of the "milk wall."

The notion that the walls are literally made of milk has been fueled by social media, with some eager tourists even attempting to taste the "freshest" wall. The truth, while still sweet, is more nuanced.

Driven by deep devotion to the sacred site, local Tibetan families often arrive with offerings for the paint - bottles of milk, jars of honey, and bags of sugar.

"It's an expression of their pure and simple sentiment," Bianba Qiongda noted with understanding. However, she quickly added a note of scientific caution. "The exact ratio of ingredients, such as milk, sugar, ox-bone glue, and plant-based glue, is determined by our veteran craftsmen based on long-standing experience. Altering this formula affects the viscosity and gloss of the paint and is ultimately not beneficial to the preservation of the cultural relic."

Each year, the administration division emphasizes to volunteers the importance of sticking to the proven recipe in order to balance the heartfelt tradition and the rigors of modern conservation.

In 2025, more than 200 professionals formed a chain of care, safeguarding this architectural marvel for future generations.

As sunset bathes the newly coated Potala Palace in soft light, the rope-access professional workers lower their equipment, and volunteers clean their paint-stained hands. This annual ritual is a vibrant festival, and also a powerful symbol of unity. People from diverse backgrounds come together to honor a shared cultural legacy, and by doing so, consistently tell the ongoing story of one of the world's most iconic heritage sites.