Final answer:
The material used to improve the adhesion of a specialty coating and to seal the substrate is called a primer or binding agent, often containing binders like synthetic or natural resins.
Step-by-step explanation:
The material applied to the surface to seal the substrate and to improve the adhesion of a specialty coating is commonly referred to as a primer or binding agent. Primers are usually formulated with specific binders such as synthetic or natural resins like alkyds, acrylics, or polyurethanes, which ensure that the paint or coating adheres properly to the surface.
These resins or polymers provide properties such as gloss, durability, flexibility, and toughness to the final paint layer. It's important that the primer is compatible with both the surface being painted and the paint or specialty coating that will be applied on top. In addition to improving adhesion, primers can also protect the surface and enhance the texture or finish of the overlying paint.