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Flux for soldering small parts


Hello friends, here I am again, I want to ask you which kind of flux
is better for solder silver and gold. I always use sodium borato
(Borax), but sometimes I have trobles in soldering, specialy when I
am soldering small parts. Does any one of you have any experience
with boric acid. Thank you: Denis.


Denis, I use boric acic and denatured alcohol_for silver and gold
soldering, and as a flux when melting metal to stop oxidation. Where
are you located in Cuba. My wife is from Varadero Matanzas.

Harold Momany


Hello Dr. Denis! Welcome to the Orchid community! I haven’t had a
chance to write to you earlier! I’m glad you’ve found us, and that
our community doesn’t suffer the problems that the international one
does! I hope that our two countries can one day be as open and
friendly as Orchid is! I understand the diving and boating in Cuba is
extraordinary, and I hope to be able to experience it soon!

I used to always use the white paste flux, called Handy Flux. It was
quite messy, but very effective for silver work. I have since been
using a green liquid flux, which is much more easy to work with. The
paste flux is much more resilient… it will continue to hold up
under longer torch times and continue to work. The liquid flux will
lose its fluxing ability (absorb all the oxygen it can) more quickly.

Boric acid, in my experience, isn’t really a flux. It acts as an
oxygen barrier, preventing the development of fire scale on the piece
as it is heated. It is an excellent dip, mixed with alcohol, to keep
the work clean, but you will still need a legitimate flux.

I hope this helps!

Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)


Denis, Try Fluoron for gold, it is cheap and also good for silver.
But if flowing is a problem try using Degussa H on silver

Boric accid is only used as a coverage against oxide stains.

Martin Niemeijer


Boric acid is nor a flux for silver or gold.

Id a borax slate and cone proves to give you too much trouble then
choose on of the proprietary solutions from someone like Rio Grande.
They are all excellent.

Tony Konrath