Molecular Mixology: Buchner Funnel

Darcy O'Neil :: May 18, 2006 8:38 PM

Buchner FunnelFor those who are aspiring molecular mixologists there is more to the “molecular” part of the title than just liquids and powders. There are some great pieces of chemistry equipment that can benefit any aspiring mixologist. The first one that I’m going to discuss is the Buchner funnel. Basically, this is a filtering device that uses a hand operated vacuum pump to pull liquids through a fine grade filter paper in a flask. Nothing sucks more than trying to filter something through a coffee filter for 20 minutes. A Buchner funnel will filter liquids in a fraction (think seconds) of the time and the costs of this device is relatively cheap (about $60). For anyone playing with bitters, a Buchner filter is a must.

Vacuum Pump

A Buchner funnel is really easy to operate. Basically you have the funnel, which has a small number of holes and a good surface area. This is to provide support for the filter paper so that it doesn’t get sucked into the flask. The funnel is connected to the vacuum flask with a rubber stopper. The vacuum flask has a nozzle where a piece of tubing can be attached. The other end of the tubing is connected to the hand held vacuum pump. Once it is setup, you pour your liquid into the funnel and that start creating the vacuum. The liquid will be sucked into the flask and the filter will remove any particulate.

In the lab we used these filtration devices in organic chemistry. Basically, we would react a number of chemicals together, in a solvent, and then create a new compound. To recover this compound from the solvent, we would precipitate it in a solution and then filter it out. The Buchner funnel allows you to remove the filter paper with the collected filtrate, where you can scrape it into a vial for storage or analysis.

Vacuum FlaskA sample application for the Buchner funnel is that you can “polish” liquids like fresh squeezed lime juice. Depending on the type of filter paper you use, you can filter out very small particles or just the large pulp. The process doesn’t strip out any flavours, but will filter out the pulp and bits of pith that float around on the lime juice. This makes for a nice clear lime juice and when mixed with other ingredients will create a good bright drink.

Another good application for this apparatus is for the home bitter blender. When you work with wild craft herbs and roots, they can contain a lot of dirt and small pieces of ground up bark. Usually you have to decant and filter the product through cheese cloth and the volumes are usually greater than a litre. A Buchner funnel can make your life a lot easier.

You can find complete filter setups on the Internet for $60.

Fix the Pumps
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