Kallynteria (24 Thargelion) is the small festival of “Sweeping Out,” and it is on this day (most likely the 24th, but the date is uncertain) that women swept out the temple of Athena in Athens, and probably Her eternal flame was refilled and relit by the priestesses. The lamp of this flame was a golden vessel wrought in the late fifth century by Kallimachos, a distinguished Athenian sculptor and metalworker, and it was big enough to hold enough oil to burn day and night for the whole year (Parke 152).
The next day was Plynteria (25 Thargelion), the festival for washing (plynteria hiera) the ancient statue of Athena Polias (Guardian of the City), a custom which continued into the fifth century BCE even after the huge gold statue by Pheidias had become the primary agalma (cult image) on the Acropolis. The day was considered unlucky because the Goddess was “otherwise occupied” and might not be able to protect her city. In fact, the other sanctuaries of Athens were closed on this day (Parke 152-4). The women of the Praxiergidai, an Athenian family traditionally entrusted with dressing the agalma, removed the peplos (robe) and jewelry from the ancient wooden image, which was then wrapped and carried in a procession to the sea at Phaleron even though the trip to the sea was a journey of several miles, as sponging it in the temple was insufficient and no Attic rivers would have carried enough water in May for the purpose. Also, the purifying effects of salty sea water were well-known (as per the Eleusinian Mysteries). The procession was led by a woman carrying a basket of fig pastries, for the fig was believed to be the first cultivated food. Mounted epheboi (young men) escorted the (covered) image in the fourth century BCE. It was brought to the shore where it was bathed by two girls, the loutrides (Bathers). Most likely, the Goddess’s dress, the peplos, was cleaned at the same time by a special priestess. That evening the Goddess was returned to the temple in a torchlight procession and was clothed with the clean peplos and adorned with Her jewels (Parke 152-4).
Robertson has a slightly different interpretation. She acknowledges that the Kallynteria are thought to precede the Plynteria but notes that “we may suppose that the second name, which is much better known, was added in order to amplify the first, not to show the sequence. On any realistic view, the washing is prior to the adorning.” The sequence of events she concludes began on 25 Thargelion, when “the image was undressed and veiled, and the robe was washed. A day or two later, on 26 or 27 Thargelion, when the robe had dried, the image was bathed and then dressed again and adorned.”
The ancient statue was of human size or less, carved of olive wood, and probably showed the Goddess seated without weapons. She wore a tall, golden stephani (crown) and She may have had a Gorgoneion (Medusa head) on her breast.
Perhaps you can do your spring cleaning on these days, taking special care to dust and tidy altars in the house.
Parke, H.W., Festivals of the Athenians, 1977
Robertson, Noel. “Athena’s Shrines and Festivals.” Worshipping Athena; Panathenaia & Parthenon, edited by Jennifer Neils, University of Wisconsin Press, 1996. Kindle Edition.