Thought this was an excellent addition to the glossary. Taken from the thread "Request critique of Restoration by Tim_S"

Tim Adams (Hankster65) asked...
Excuse me...but, what the heck is "substrate?" (Pardon my ignorance here.)

Jeaniesa asked...
P.S. Can you please define "substrate" in the new Definitions thread? Thanks!!

The answer compliments of Greg Couch...
A substrate is simply the underlying material upon which the image or graphic is applied to. In the case of Tim's photo, the substrate is porcelain. If you get a photo silk-screened onto a shirt, the shirt is the substrate.

Thanks Tim, Jeanie and Greg.
DJ

Ahh ha! Thank you...good example!

Actually it's a bit more complex than that. What is referred to as the "base" or "support" is generally from four support groups, metal, glass, plastic and paper. The Subbing / Baryta or isolation layer is a sort of a go-between that has the purpose of maintaining the separations to achieve fine image details without the base showing through.

The "subbing layer" is an intermediate adhesive layer designed to assist in adhering the gelatin binder to the plastic. Historically, the albumen process is considered to represent a transition as the subbing layer is associated only with the production of plastic supports not the earlier photographer hand fabricated materials.

For all practical purposes "sub" may refer to the layers below the emulsion but technically it's actually just a shade above the base! "Substrate" may be used to refer to just the base or support alone ...or then again it may be referring to the whole package of layers between the emulsion and the hand that is holding the print depending on who you are talking to and how technical you want to get ...just thought I add a little something for you to think about!

Jim Conway