Far better than pouring a chemical cocktail down your plug hole. You'll get an instant result, too. Whether you're using a plunger or a gas cartridge, make sure that you fill the sink before you try to unblock it. The plunger has to be well under the water level for it to work well.
This'll do the business:
http://www.diy.com/diy/jsp/bq/nav/nav.jsp?action=detail&fh_secondid=9271679&fh_location=%2f%2fcatalog01%2fen_GB&fh_search=plunger&fh_eds=ß&fh_refview=search&ts=1195674655678&isSearch=true
Far better than pouring a chemical cocktail down your plug hole. You'll get an instant result, too. Whether you're using a plunger or a gas cartridge, make sure that you fill the sink before you try to unblock it. The plunger has to be well under the water level for it to work well.