Albumen prints were introduced in 1851 by Louis Désiré Blanquat-Evrard. While salted paper prints are comprised of a single layer of paper support that contains the image particles, albumen prints have two layers. When albumen (egg white) was applied to the paper support, a binder layer was also created. In an albumen print, the image sits in the binder rather than in the paper fibers as in a salted paper print. The albumen binder, which could be thin or thick, created a smooth, sharp appearance. Photographers also used special burnishing tools to attach albumen prints to a mount, which resulted in an even smoother, glossier surface.
Use of the salted paper print process lasted well into the 1860s and was for a time contemporaneous with albumen prints. The two processes incorporated many variations during this period and produced prints with sometimes similar appearances. As a result, salted paper prints can be misidentified as albumen prints and vice versa. Albumen, gelatin, resins, milk whey or various starches, for example, were sometimes added to salted paper prints for paper sizing before processing or applied as coatings on prints after processing. These salted paper prints exhibit a smoother, shinier, sharper appearance similar to albumen prints. Similarly, albumen prints coated with albumen or other organic materials can have the same appearance as coated salted paper prints. In addition, albumen prints with a thin emulsion layer (and thus semi-matte appearance) can sometimes be confused with salted paper prints that had additional sizing or coating.
Various terms in the literature used to describe prints made during this period include dilute albumen, albumenized salt print, starch print, hybrid print, transitional print, or so called low sheen prints. In the Harvard survey, prints with a single layer (including those with additional sizing or coating) were identified as salted paper prints and prints with an albumen binder or so-called emulsion layer were identified as albumen prints. This transitional period has been a topic of interest and research for conservators, conservation scientists, and curators. Instrumental analysis can aid in the identification of these photographic processes to determine if they are salted paper prints with added albumen or other starches or if they are albumen prints.