Three 9's is OK.  Pure fine silver wire from aforesaid precious metal merchants 
at either 99.98% or 99.99%, difference is not worth worrying about.  That extra 
.2% for 4x9's cost a little more.  I don't bother with that .2%, 3x9's work 
fine for me.
N.

From: [email protected]
Date: Sat, 20 Oct 2012 20:03:57 -0400
Subject: Re: CS>Wires// Canadian silver dollars
To: [email protected]







In a message dated 10/20/2012 12:36:44 P.M. Eastern Daylight Time, 
[email protected] writes:
You can 
  use silver wire or coins(as long as at least .999 
pure)


I believe they said to put a small hole in the coin 
& suspend it into the DW with a bit of silver wire.  The silver dollars 
are four nines pure not 3.. Lois