Dako was originally a container to spit saliva or phlegm. It is said that it lost its utility later.
Though "Wamyo-sho" (a dictionary compiled in the Heian period) mentions it as a bathing tool, it is said to have been one of the interior ornaments in the Heian period. It was made by silver, and usually put on the right side on the lower shelf of Nikai-dana (a stand with two shelves).
A container called 'Dako' with a depth of approximately 4.5cm and diameter of approximately 28.5cm was on a pod with a depth of approximately 6cm and diameter of approximately 4.2cm with a approximately 9cm tall standard.
It was put on a pedestal approximately 30.6cm long and approximately 30.3cm wide like a lid.
"Engishiki" (an ancient book for codes and procedures on national rites and prayers) mentions 'a silver Dako with a diameter of 25.5cm.'