Does anyone know how to preserve individual rose petals with a coating that allows them to be used as hand soap?

I was in a bathroom at a nice restaurant in Green Lake Wisconsin (near Milwakee) this summer and instead of liquid or bar soap they had these gorgeous, fresh-looking rose petals that had some kind of translucent coating with a satiny feel that lathered up in water. You just discarded the petal after soaping up.

This weekend I collected some rose petals and tried dipping them in melted vegetable glycerine soap base. But the heat wilted and ruined most of the petals. Those that stayed somewhat intact had a rubbery texture and weren't at all like the ones I used at the restaurant.

Any ideas for the type of treatment used on the soapy rose petals would be appreciated.