When you remove background photoshop from glass, clear plastic or other transparencies, you could also lose valuable transparency information and/or background reflections. These types of subjects will need to be carefully masked, adjusted and highlights preserved to ensure a realistic appearance, Visuals Clipping recommends working on separate layers which will allow access to the original image for reference. The objective is to isolate the object from the background so that the glass does not appear opaque and that details that convey the shape are not removed.