The black wax used for protection in
KOH etch is called 'Apiezon Wax W'.
Vendors are:

1. Scientific Instrument services
   (908) 788-5550  -phone
   Apiezon Wax (APW) - $102 a box

2. VWR
   1-800-932-5000  -phone
   Apiezon Wax W - $106 a box

Hope this helps.
Thanks to everybody who responded!!

******************************

Kavita Chandra
MEMS Design Engineer
Wilcoxon Research Inc.
(301) 216-3032 -voice
(301) 330-8873 -Fax