Which tool is best for applying cement to the joint of a PVC pipe?

The best tool for applying cement to the joint of a PVC pipe is a pure bristle brush. This tool is specifically designed to handle adhesives and solvents effectively. The bristles allow for even distribution of the cement across the surface, ensuring that it penetrates all areas needing adhesion. Additionally, the flexibility of the bristles helps reach into the joint's grooves, providing a thorough application that is essential for a solid bond.

Using a foam brush, although it may seem like a good choice for distributing liquids, can lead to uneven application and may not hold up well when working with the thicker chemical properties of PVC cement. A paint roller, on the other hand, is not suitable for this task because it is designed for larger surface areas and would not provide the precision required for the small joints in PVC piping. An applicator gun is typically used for caulking or dispensing viscous materials but is not suited for the same precision required for applying cement to join PVC pipes.