On his birthday Thais wore yellow, when he got sick they put on pink, and now that King Bhumibol Adulyadej has passed Bangkok's streets have turned monochrome in a extraordinary display of collective grief.

The venerated monarch died at the age of 88 on Thursday, plunging the nation into mourning and leaving a politically divided people bereft of a rare unifying figure.

Thailand is a country that leans heavily on symbols and people have long expressed devotion to the king through clothing, with many in Bangkok sporting yellow every Monday, the day he was born.

Pink became the hue of choice in the sovereign's final days out of the belief that it would bring him good luck as his health declined.

But since his passing most in the distraught nation have for the first time honoured the late king in black, with tens of thousands pouring onto the streets in unprecedented displays of sombre devotion.

All government staff have been ordered to forgo colours for an entire year and many private businesses are asking employees to don black for at least a month.

That has sent shoppers rushing to snaffle up black garments from street vendors and luxury malls who swiftly replaced their stocks -- and even their mannequins -- with mourning attire.

At a streetside stall at Pratunam, a bustling wholesale market in Bangkok's commercial heart, Somporn Sriwichai is raking in more money than she has in weeks selling t-shirts and polos for between 150-250 Thai baht ($4-7).

"All of us in Thailand are very sad and I don't want to be selling black clothing," said the 45-year-old, who normally sells children's dresses.

"But I have very little money and now I have something I can really sell," she said, adding she shifted 100 items on Friday alone.

Like many of the city's streetside clothing hawkers, Somporn rolls out special merchandise in lockstep with royal events.

For the king's birthday on December 5 the shirt's are yellow. For the princess's they are purple.

Last year a mass cycling event led by the Crown Prince saw hundreds of thousands sport yellow-and-blue polos bearing the name of the event, "Bike for Dad".


Grieving all day

The sudden demand for black has sparked fears of a national shortage, with the government saying it will work with manufacturers to ensure supply as well as crackdown on opportunist price-gougers.

"We want the world to know our feelings," Somporn said, explaining that "by wearing the same colour shirts and being united we can express our grief all day."

While royal occasions have often brought uniformity from Thais, the realm of politics is defined by acrimony.

For the past decade Thailand has been torn apart rivalling camps known by their opposing colours: a populist "Red Shirt" movement and their foes -- a royalist elite-backed "Yellow Shirt" group.

The colour-coded political tribes have staged repeated rounds of mass protests over the past decade, often bringing Bangkok to a standstill and sometimes spilling into violence.

Though Bhumibol had in the past drawn upon his moral authority to avert political crises, the monarch remained mostly silent during the twilight of his reign as the colour wars rocked the kingdom.

The ruling junta seized power amid the latest show of protests in 2014 and vowed to restore order and encourage reconciliation.

But critics say the army's tight grip on expression has only temporarily buried the nation's strife, leaving open the possibility of a new flaring of the country's fiery political divides.