Primers typically contain a small amount of ____ and a large amount of ____.

Primers are essential in the application of roofing systems, particularly in built-up roofing (BUR) systems. They serve as a preparatory layer that enhances the adhesion of roofing materials to the substrate. The correct understanding of a primer’s composition highlights its effectiveness in this role.

Primers typically contain a significant amount of solvent, which helps to dissolve and carry the asphalt or other binders into the surface it's being applied to. This solvent facilitates the uniform distribution of the primer and allows it to penetrate the substrate, improving adhesion. The asphalt content in primers serves as the bonding agent that adheres to the subsequently applied roofing materials.

The choice of a small amount of asphalt in relation to a larger amount of solvent in primers is crucial. It ensures that the primer remains fluid enough to be easily applied and allows for drying, which is essential for forming a strong bond with the roofing materials that will be layered on top of it. The combination of these components ultimately provides the necessary performance characteristics that make the primer effective in protecting and securing the BUR system.