Which preposition to use with shirtwaists

at Occurrences 1%

"That there was anybody left in the world who could look like that in a white shirtwaist at 6:30 A.M. Is that all your own hair?" "Strictly.

for Occurrences 1%

She thought about her at night when she was washing and ironing her other shirtwaist for next day's wear.

Which preposition to use with  shirtwaists