We use this routinely:
Variable transformer, e.g.12 volt microscope lamp transformer or "variac".
Carbon rod. We used to get them out of old disposable batteries.
Tungsten wire held in metal pin holder (ensure there iselectrical contact
between tungsten and holder). Scrape end of tungsten wire with scalpel
blade to remove any coating.
Leads with alligator clips
NaNO2 solution: Dissolve 71g NaNO2 and 34g KOH in 100ml distilled water in
jar with screw top. If this solution spills onto benchtop or skin, wash
immediately. It is very alkaline.
Connect carbon rod to one pole of transformer output via lead.
Immerseone end of carbon rod in NaNO2
Connect your pin holde to the other lead with alligator clip
Turn transformer on low and dip the tip of the tungsten wire in and out of
the solution by hand. Solution will bubble. Regulate degree of sharpening
by voltage and dipping rate.
If you get alternative recipes, please post them for everyone's benefit.
Dave Merritt (email: dmerritt at metz.une.edu.au)
University of New England
Australia (fax: 67 71 1869)