BANGKOK — Pop-up clothes dyeing centers are a new phenomenon in the Thai capital as black apparel becomes too expensive for many following the death of King Bhumibol Adulyadej.

The Thai government has declared national mourning for Bhumibol, who died Thursday, and some clothing sellers have been quick to hike prices for black garments. Others have run out of stock.

Vats of black dye were boiling nonstop Monday at a free dying station set up in downtown Bangkok by a tractor importing company.

Volunteers rushed to write down names and contact information from a stream of visitors bringing in colored clothes.

“Some people don’t have black clothes or don’t have enough to wear,” said Kanokporn Tantranont, a Krung Thai Tractor employee helping out at the center. “If you go out to buy more clothes, the prices are so high,” he said.

His employer says the dyeing station will stay open until the end of the month and people can also donate old clothes to be dyed black.

Bhumibol’s death after a reign of 70 years has triggered an intense outpouring of grief in Thailand, where the monarchy is revered. And some people have taken to criticizing others who don’t strictly conform to the mourning dress code, which allows black or black with white.

Department stores have dressed up their mannequins in all-black attire, and anything flashing red, green, pink or the like has been moved or hidden.

But for some, restocking their closet is not an option.

Waiting for his newly dyed black clothes, Kamol Samutsal, a 43-year-old office worker, said some dye shops in Bangkok have been profiteering as well.

“It has become as expensive as buying new clothes,” said Kamol. “I think it’s good that they provide a free service to the public here.”

Deputy Prime Minister Wissanu Krea-ngam said people shouldn’t be criticized for not wearing black or white because feelings of grief come from the heart, not what clothes are worn.

Government workers are required to wear black mourning attire for one year. State events are also under a 30-day moratorium, and all public offices and schools will fly flags at half-staff for 30 days.