"Abso" wrote in message
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I've tried a traditional plunger on the kitchen sink, and a syringe
type plunger but both merely blow crap out of the overflow (straight
down my shirt, lovely). I can't think of a way to block the overflow
to increase the pressure so I'm looking for alternatives.


With many types of overflow design, the traditional way to block them up,
whilst using a plunger over the plug hole, is to ram a damp cloth into the
overflow - often works remarkably well.