When I ran a chemical reuse website, the request I got over and over was for help with setting up a project to reuse little bars of soap from hotels. So I got to wondering what kind of redesign could be applied to soap bars.

I still don’t know what to do with those tiny bars they use in hotels, That might require an industrial strength redesign of the whole practice of soap packaging since hotels are more focussed on patrons’ perception of neatness and newness than with anything else. This focus leaves fewer available neglected parameters. But when it comes to bar soap used in homes, there is a neat way to increase the reuse.

As usual, it involves changing one of the neglected design parameters to increase reuse. In this case, it is the shape of the bar. What if one side of the bar had a recess in it that was made to receive the typical, small, used up former soap bar? In other words, when a bar becomes too small to use, the homeowner would open up a new bar, wet it up, and then place the wet, soapy, small residue bar into that recess. As soon as the two had a chance to dry together, they would stick. Subsequent wettings just add to the adhesion until the two are welded together.

I do this anyway, today, but with smooth or flat or curved surfaces it is difficult and most people wouldn’t bother. If a pre-engineered recess were available, the tendency for the two pieces to slide apart would become less annoying and everyone could use the trick.

Of course there is a missing link. A study would be needed to determine the typical shape of a used bar of a soap and the best recess for holding it. This is a very small project. Some soap molds would need to be changed and the packaging would need to announce a new Zero Waste reuse ability. More and better advertising for Zero Waste.