At the time Christian A. Peterson's book "Chaining The Sun - Portraits by Jeremiah Gurney" was published in 1999, this was the only Gurney ambrotype known to exist. Formerly in the collection of Carl L. Peterson (no relation to Christian Peterson), we are very excited to add it to our collection at Alphonse Gallery.
The collodion image is on the back side of the glass - vs. on top of the glass like most ambrotypes. The black back painting was applied over the collodion image. Over time, tension between the 2 layers caused the image to crackle and lift from the glass as shown. This may have been an experiment by Gurney to make the image more durable - without adding a top cover glass.