[Jewelry making - Article 00899] - Re: [Orchid] Using MAPP gas for silver work?

[James Binnion]

========[ Invite a Friend - http://www.ganoksin.com/invite.htm  ]========

>     This is the first I've heard of this torch. Why does it mean there
>     is little chance of firescale or using up flux? 

    This is the torch I learned to solder with back in high school in
    1970. It has been around for a lot longer than that but I have used
    it on and off since then. 

    Flux is acting as a barrier coating to the oxygen as well as a
    reducing agent. As a barrier it prevents oxygen from reaching the
    metal and as a reducing agent it combines with oxygen in the air and
    will also strip oxygen from the oxides on the metal surface leaving
    behind pure metals. The problems in using flux come from not getting
    a good complete coating to act as a barrier, and in overloading it
    with oxygen by having it at heat too long, leaving too much oxide on
    the metal surface before applying the flux and having too much
    heated oxygen around it. The gas air torch addresses the time at heat
    and too much oxygen problems. The flame size from these torches are
    much larger in diameter than the oxy-fuel torches used for the same
    work. This allows you to bathe the whole piece or at least a sizable
    chunk of it in the flame. This heats the entire piece faster so there
    is less time at temperature, the large flame if properly adjusted
    consumes all the oxygen in its confines so the area inside the flame
    is not getting exposed to excess oxygen while soldering. Oxy-fuel
    torches are almost always producing an oxidizing environment except
    at the very tip of the inner cone on neutral or even moderately
    reducing flames. This is because the pure oxygen mixed with the fuel
    does not completely combust due to less than perfect mixing and it
    therefore will not consume as much of the oxygen from the
    surrounding air in the secondary flame as a gas air torch. With gas
    air there is just less oxygen present. It is also an improvement over
    a naturally aspirated torch (prest-o-lite or bernz-o-matic or little
    hand held butane models) because you have total control over the mix
    of fuel and air and do not rely on the venturi used by those types of
    torch. So if you want a more reducing flame you just turn up the gas
    or turn down the air. 

>     What is the source of the compressed air? Do you run a compressor?
>     They are very noisy! 

    Yes you need a compressor, and most compressors are noisy. I have
    mine outside the studio for this reason. This is the big drawback of
    this type of torch. 

>     I have three or four torches already, but anything that minimizes
>     the chance of firescale gets my attention! 

    Most times I solder with this torch the flux is left as a clear
    glassy coating with little if any black or green flux glass. Such
    dark coloration is an indication of the flux being overloaded with
    oxygen. This clear coating comes off easily and leaves behind a
    metal surface that is little affected by the soldering process. 

Jim

James Binnion
jbin AT mokume-gane.com
James Binnion Metal Arts
http://www.mokume-gane.com
360-756-6550

 
____________________________________________________________________
T h e   O r c h i d   L i s t
Open Electronic Forum for Jewelry Manufacturing Methods and Procedures
____________________________________________________________________
Orchid FAQ:
~ http://www.ganoksin.com/orchid/faq.htm
Orchid Archives:
~ http://www.ganoksin.com/orchid/archive
Orchid Galleries:
~ http://www.ganoksin.com/orchid/gallery.htm
Invite a Friend:
~ http://www.ganoksin.com/invite.htm
____________________________________________________________________
Tips From The Jeweler's Bench - Article Archive
~ http://www.ganoksin.com/borisat/tip_sear.htm
The Jeweler's Selected Bibliography List
~ http://www.ganoksin.com/jewelry-books
Buy Orchid Jewelry:
~ http://www.ganoksin.com/shop
____________________________________________________________________
-Unsubscribe:
-Email: orchid-request AT ganoksin.com Body=unsubscribe subject=blank
____________________________________________________________________