What’s the composition of the (slighlty sticky) substance we find on foam earplugs that allow them to be easily moldable?
This substance slows down the expansion of the foam, so it makes the foam a little bit more rigid and help the foam to stick into the ear canal. (It might also have some insulation property in combination with the foam.) This substance get out when you wash the earplugs with soap, it's probably sprayed on the foam, or impregnated on the foam.
Any idea ?