However, it became clear that this mechanism served a dual purpose: to measure out enough product and control flow as a stopcock (like one would find in a scientific buret). Because there were fins (on the white rotating part of the dispensers shown above) that were the diameter of the channel, between uses, the product would be sealed from freely flowing out the bottom of the container.
This design was not used because there is no simple way to stop the flow of product when not in use while still allowing for accurately measured ½ or 1 teaspoon in volume outputs in use.
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