Manifests as: change in surface reflectivity
Primarily caused by: moisture, heat, light, pollution, and/or abrasion
Gloss change is caused by various harmful forces that result in a change to the reflectivity of the surface of the print. Change in gloss for traditional photographs typically occurs when the print is in direct contact with a smooth surface and exposed to high humidity. This form of gloss change is usually referred to as ferrotyping (see below). Gloss change for digital prints can occur whether they are in contact with adjacent surfaces or not. It can result from high humidity but also from light, pollution, abrasion, and heat exposure. The resulting surface damage can be widespread throughout the print, or localized in small areas. Gloss change most often occurs to prints that originally had a high-gloss surface.
The images above were taken with the same illumination angle to maximize the specular reflection. The original image shows full gloss with high reflectivity, and the girl’s face is barely noticeable. The second image shows how loss of gloss has reduced the print’s reflectivity making the girl’s face visible.
Ferrotyping and Blocking
Ferrotyping can occur when traditional photographs or polymer photo-coated inkjet prints are in physical contact with smooth surfaces – such as glass, plastic films, or other prints – under high humidity. Ferrotyping is usually not even throughout the whole print resulting in localized changes in gloss. In the most severe cases the print becomes bonded to an adjacent surface. This is called blocking. The image below is a digitally printed chromogenic photograph blocked to framing glass. Inkjet, electrophotographic, and dye sublimation prints for the most part are unlikely to block, although some may ferrotype.