There is an advertising illustration of a woman wearing a silk slip and washing her hair in a pool of water by John La Gatta (1894-1977) coming up for sale on June 5, 2018 at Swann Auction Galleries.

https://catalogue.swanngalleries.com/asp/fullCatalogue.asp?salelot=2480+++++127+&refno=++743505&saletype=

See this link to the National Museum of American Illustration for more information about the artist,

https://americanillustration.org/project/john-lagatta/

The illustration in the sale might have been done for Laros Lingerie c. 1940 for either a magazine ad or Laros catalog.

Below is an similar illustration by La Gatta for Laros:

In 1938, Laros come out with “Dimensional Slip” which was billed as the best fitting slip on the market:

This image comes from a history of the company:

http://www.lehighvalleylive.com/bethlehem/index.ssf/2018/01/how_you_can_help_chronicle_leh.html