Most commercial solder fume extractors use activated charcoal filters.
I guess it depends what you need to keep away (particulate, volatiles, etc..).
There may be regulatory requirements on the level of worker protection and a furnace filter may not always meet them.
If the room is large and the soldering minimal a simple fan without any filter drawing the fumes away from you works fine.
Dilution is the solution to pollution more often than not.
As someone mentioned the smoke tends to home in on your face, it has to do with the air currents created by your body heat and breathing.
The fan needs to be slow and larger diameter, any strong draft will interfere with soldering.
Many production places vent outside the building rather than use filters.
Depending on what you make downdraft benches with perforated metal tops can work out better than hoods or elephant trunks.
Also there are vast differences between flux types, some bother me much more than others.
ST
On Mon, Jul 21, 2014 at 8:20 PM, Daniel Donnelly KC7VDA@... [Homebrew_PCBs]
<Homebrew_PCBs@yahoogroups.com> wrote:
My stepfather solved the problem for under $15.00, He put a box fan with a furnace filter on my bench ... end of problem. No expensive fume hood needed.