Date:         Fri, 15 Jun 2012 17:02:49 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: friday - home made rosin flux
Comments: To: neil n <musomuso@GMAIL.COM>
In-Reply-To:  <CAB2RwfjRnyZOZSEavwThRYV50mx1nhRZodjMZtbOhOSY1wjreQ@mail.g
              mail.com>
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At 03:55 PM 6/15/2012, neil n wrote:
>And speaking of DIY flux, one can use Borax for silver brazing flux!

Ordinary powdered flux for "bronze" brazing is 
largely borax, but silver-brazing flux is a lot more complex (and nasty):

>Silver-brazing fluxes contain boric acid and 
>potassium borates, combined with complex 
>potassium fluoborate and fluoride compounds. 
>Fluorides, up to 40 percent in flux content, 
>give these fluxes their characteristically low 
>melting points, 1,050º F. and high activity for 
>dissolving metal oxides. Silver-brazing fluxes 
>that contain elemental boron offer improved 
>protection on carbides and on materials that 
>form refractory oxides such as chromium, nickel, and cobalt.

;-)
d