They are held for deceased members of the royal family, and consist of numerous rituals which typically span several months to over a year.
Today, the cremation ceremonies are held in the royal field of Sanam Luang in the historic centre of Bangkok.
The body is brought to the cremation field in an elaborate procession featuring great funeral carriages, and days of theatrical performances are held.
Today, it is held in the Phiman Rattaya Throne Hall in the Grand Palace, and is attended by members of the royal family and senior government officials.
For high-ranking royals, a gold death mask is placed on the body (after sealing the orifices with wax, in times before embalming).
This is performed by officials of the phusa mala, an ancient court office responsible for, among other things, maintaining the king's wardrobe and attending to the bodies of royals after death.
It consists of two layers: an outer shell, usually ornately decorated, with two opening halves and a pointed lid; and an inner cylindrical container known as long.
[10] For high-ranking royalty today, the kot is enshrined on a decorated pedestal known as bencha in the Dusit Maha Prasat Throne Hall of the Grand Palace.
A long strip of cloth known as phusa yong, tied to the shroud within the kot and passing under the lid, is laid down to symbolically connect to the deceased during the sadappakon ritual.
Despite the Sanskrit origin of the term, such urns were not used by Medieval cultures of the Indian Subcontinent, from which the practice of cremation spread to Thailand, along with Buddhism.
In modern times, this has become analogous to lying-in-state, although the practice predates Western contact and did not originally serve to allow the public to pay their respects.
[15] While these rites were also historically private affairs, members of the public have been allowed to pay their respects in the Dusit Maha Prasat Throne Hall since the funeral of King Chulalongkorn, in recent funerals the main public vigils are also broadcast on radio and TV and livestreamed online.
[19] The construction of merumat for royal cremations date to the Ayutthaya period, as Hindu beliefs were absorbed from the Khmer Empire.
The one built for King Narai (died 1688) was recorded as being 3 sen (60 fathoms) tall—120 metres according to modern conversion rates.
[14] The practice of building very large merumat was last seen in the funeral of King Mongkut (Rama IV, died 1868).
His successor, King Chulalongkorn, expressed his distaste of the waste of labour and money, and ordered that a simple structure be built for his cremation instead.
Since then, royal funerals have employed such simplified designs for the merumat and men, and the terms are now only used to distinguish the rank of the deceased.
[20] Following cremation, the merumat or men is disassembled and the components and materials are usually donated to Buddhist temples or to charity.
[22] As the merumat is being built, restoration and maintenance work is also done to prepare the royal funeral chariots for the cremation ceremony procession, and practice sessions are held.
In the past, the partially-decomposed flesh would also be removed and stripped from the bones, in order to be cremated separately, but embalming has rendered this process unnecessary.
This is done out of necessity or for convenience, e.g. in cases where the site is far from the procession route, or, in modern times, where body is placed in a coffin rather than the kot.
It is an old tradition dating back to the Ayutthaya kings which saves time for the royal funeral procession within hours.
[26] Entertainments and theatrical performances used to feature largely during royal cremation ceremonies, but were discontinued during the funeral of King Chulalongkorn.
Recent developments introduced in the late twentieth century include live television broadcasts of the ceremony, as well as increased public participation.
In Cambodia, the late King Norodom Sihanouk received a royal cremation in 2013, more than 50 years after the ceremony was last held.