This is a negative photograph of a sculpture by Ruth Asawa. Ruth and Imogen were great friends, and Imogen took photographs for Ruth both as a document of the artwork and also as a creative endeavor. In this case, Imogen found the negative image quite interesting, so she made an inter-positive in the darkroom, and printed from that media to make a final image, in negative. Looking at these prints, we discovered that they were photographed in natural light, on Imogen's back porch in the sunlight.
This is a larger print from Imogen's archive. Printed by Imogen herself, she normally did not print in this size. The print itself is in excellent condition, with very minor imperfections only under quite close inspection. This is a vintage print, and does not fluoresce under black light inspection, indicating a 1950s vintage paper.
The verso of the print has Imogen's Green Street stamp and a publication work stamp as well.