Which type of roller covers is most effective for applying primer?

Ultrahigh density foam covers are the most effective choice for applying primer because they have a very smooth surface that allows for even and consistent application of the primer. Their dense structure helps to minimize the occurrence of bubbles and ensures that the primer goes on without leaving streaks or lines that can result from other types of rollers.

These foam covers are also less likely to shed fibers, which is beneficial in achieving a clean finish, especially important for low observable aircraft where surface smoothness is critical for radar evasion. Additionally, ultrahigh density foam can hold a substantial amount of primer, allowing for a more efficient application process.

In contrast, standard bristle covers may leave brush marks and aren't as ideal for smooth finishes. Polyester covers can absorb too much product, resulting in uneven application. Nap-covered rollers can contribute to texture on the surface that is undesirable for primer application, making them less suitable compared to ultrahigh density foam.