On 8 Jan 2005 15:43:55 -0800, jim rozen
wrote:

If you have trouble with the solder running where you don't
want it, that can be remidied with "stop-off" which is a paste
or paint sold expressly for the purpose of preventing silver
solder or braze from adhereing where it isn't wanted.

Milk of magnesia. Paint the areas to be stopped off with it.It repels
the solder. We use it at work when furnace brazing all the time, and
jewellers use it as well.