A strap running through a buckle is typically easy to loosen and tighten as desired. Usually, it stays in place. Sometimes, however, it slowly (or quickly) works its way loose, as though the thickness or smoothness of the webbing doesn't quite match the size or shape of the buckle. What can I do to make the strap more grippy?
The specific problem I have is with a new backpack (no wear and tear), and it happens in dry conditions (not wet and slippery). The straps even have cloth-elastic bands wrapped around, right next to the buckles.
One method could be to add a separate clasp, as per this question. Also, I imagine I could intentionally soak it in sea water and then not rinse it, leaving the salt crystals to gum up the works (I know this happens to kayak gear and it's usually a nuisance). Other techniques? I consider replacing either the strap or the buckle to be too drastic a solution.