I thought my method for removing old duckbills might be of interest to the members. Recently I had left an eyedropper with a rubber bulb submerged in an isopropyl alcohol solution, only to find it in pretty bad shape which got me to wondering what it would do to an old duckbill. Since I had one that was in really bad shape I decided to experiment a little. As you can see from the photos, it was hard inside the can and bonded tightly to it. In contrast, inside and outside the exhaust port of the can was a gooey mess. I soaked the can in denatured alcohol for 24 hrs and was pleased to see the results. The entire duckbill has pretty much dissolved and what little remained was easily removed with a rag or wood tool. Denatured alcohol is easy to find at pretty much any hardware store, does not smell too bad and is a lot safer to use than most any other chemical I know of that will remove the rubber.
Cans before cleaning:
Cans after soaking for 24hrs in denatured alcohol. Other than a sloshing of the alcohol, no mechanical means of cleaning were used. The container is shown here laying flat, while soaking I had it raised at one end to keep the exhaust port submerged which allowed me to use less alcohol.
Cans after a light cloth rub and rinsing:
