The vast majority of sanding discs are available in both self adhesive (PSA) and Hook & Loop (H&L) forms, and for many people, which they prefer is almost as hot a topic as their favorite sports team. But both mounting styles are valid, and while one may be preferred over the other within particular industries, there are very few shops where there is no place for both.
Air sanders generally come with PSA sanding pads, whereas electric sanders are more likely to come standard with H&L pads, but there may be times when it make more sense for you to use H&L over PSA, and vice versa. Sander manufacturers usually have both types of mounting pads for all their models.
The biggest difference between the two mounting methods is that PSA discs cannot generally be reused and must be thrown away each time you change the sandpaper; H&L discs, on the other hand, can easily be reused.
So, why does this matter? When you’re sanding, you need to change grits as you refine the finish on your piece. H&L discs can be changed rapidly and reused; PSA discs can do neither. This makes H&L very convenient on a job site because one sander and a selection of discs can handle most jobs whereas PSA discs are wasted as grits change or a separate sander is needed for each grit to be used.
The hook for the pads on hook & loop provides a slight cushion, so H&L discs work better on mild curves and surfaces that are meant to be contoured. This can be an important consideration to the work. In contrast, PSA pads are flat and stiff -they don’t follow curves, but they also do not tend to round corners and do not follow contours. This makes them ideal for leveling surfaces. Depending on your application, this can help you choose which type of mounting system to use.
Like most things, there is no magic bullet, and most shops that do any sort of finishing will have both PSA and H&L sanding discs on hand to get the best results for the task at hand.