This is the first of an on going feature of this list called Silver
Supplies. I will discuss different chemicals, compounds, and supplies
that I use. I will also try to explain why I use them instead of some
of the others. I, of course, encourage you to add your comments, and
suggests of different supplies that you use and like. If I have not
tried them, I will and let the list know how I liked it. If you have not
used the supplies that I recommend please do compare another one as
being better. All I ask is that you try "My Way" before you compare.
Supplies 1, Flux
Photos for this Lesson can be found at:
http://www.frii.com/~dnorris/slapa.html
Flux
What is flux? I don't know; I don't care. I use Battern's
Self Pickling
Flux. Photo 1 and 2
I use it with by spraying it on with a spray bottle, photo 5,
not a brush as the bottle suggests. Photo 3
It says it has some kind of acid in it. Photo 4
Because of
this, use
all the safety precautions that you feel necessary. Keep it
off your skin,
do not drink it, do not spray it in your eyes,
ventilate your work area, wear a mask, safety goggles or
glasses or face
shield, and perform all other safety measures that
make you comfortable.
Flux does not clean the metal as most books state. I once
had a class of
11 people bring all kinds of cleaning agents to
clean silver before we soldered. We had steel wool,
ammonia cleaners,
ultrasonic cleaner, soaps, detergents and even a
bottle of something that a science teacher brought, that
smoked when he
took off the stopper of the glass bottle. I
made him take that back to his a car and leave it there!
We used each,
and a combination of each to clean the silver.
Then we tried to solder without flux, and had no success.
Then we
added flux, and the solder flowed and did a great
job of soldering. I just wanted to prove that I did not
believe flux
cleaned the silver. The silver in all these cases
could not have been cleaner. We concluded that flux did
something else
besides clean the metal. We also noticed that
it coated it with a crusty crud. Certainly not clean!
So we went back to the physics books and learned how
solder works.
Solder works just as most glues. It flows into pores (small
holes) in
the surface of the metal and is trapped there so it
cannot get out. This holds the two pieces of metal
together, but
it is a little more complicated than that.
How Solder Does Its Job
As you heat the metal to be soldered, it expands. As it
expands, it opens
up these pores, or at least they also expand
and become larger. Because the solder flows at a lower
temperature than
the sterling silver melts, the solder melts and
flows into these enlarged pores. When the torch is
removed, the solder
solidifies and hardens in these pores. Then
sterling silver cools and "shrinks back to it's normal size,
including the pores. This traps the hardened solder in the
pores so that it can not be pulled out, and the pieces are
soldered
together.
Does this makes sense to you? If not, it is time for more
questions!
Please ask!!
This is different from welding. In welding the two pieces
of metal (and
sometimes a third metal as a filler) are
actually melted together. Both pieces, or all three, are
melted and then
combine to form a weld. This is a joint where all the
metal has melted, flowed together, and combined to make
a separate "metal"
that contains some of each of the pieces used.
This is very different than soldering. Welding is sometimes
called fusing, and
is used for some artistic effects. I very seldom
ever use fusing for silversmithing. To me it always looks as
if two
pieces were just melted together. Oh, well that is
an entire discussion for later debate.
If you understand soldering, then we also need to explain
"oxidizing"
and oxidization. As metals are heated,
especially with a torch, oxygen from the air will mix with
the heated
metal and oxidize it, burning it. As with everything
in the universe, this is just magic. Oxygen likes to mix with
things and
thereby change them. In the case of most
metal it sort of burns it. As it does this, it creates a dirt, an
ash, or
microscopic crud of some kind that coats the surface of
the metal. This crud inhibits the solder from flowing across
the surface
of the metal and blocks the pores so the solder
cannot flow into them. If the surface gets oxidized, you
cannot
solder. It is as simple as that.
What flux really does then, is coat the surface of the
sterling silver, making it so
oxygen cannot get to the surface and oxidize it. Because
of this,
the solder can flow across the surface, into the
pores, so that the pieces get soldered. Simple, yes?
The only time I have seen this explained in this way, in 30
years, is in
the Rio Grande catalog. Check out their
description of flux.
I also believe that flux does something else. I believe that
it acts as
a surface tension reliever. You know, like the
stuff you put into you dishwasher, to keep water spots off
the glasses.
If you read what it actually does, it is to relieve
the surface tension of the glass so that the water runs off
the glass.
This makes it so there are no drops left on the glass to
leave spots. I believe flux acts like this too. I think that as
it
"melts" on to the surface of the metal, it coats it. It
also, helps the solder flow by making the surface
slippery. The solder
can slide over the surface as it pushes the flux
out of the way.
I had a member of this list let me know that the dishwasher fluids say
that it reduces the surface tension of the water and not the glass. I
will accept that, and them just add that flux may reduce the surface
tension of the solder and not the metal to be soldered. It is OK with
me, the results are the same.
Flux goes through several stages as it does its job. We
will spray it on.
We will use a $1.00 spray bottle from Walmart
or other such store. It goes on as a liquid, and as you heat
it, it
dries into a crust. This crust can be quite bubbly. As
you keep heating the flux it will smooth down to a thin
coat. Then as it
is heated to a higher temperature, it actually
begins to melt into a syrupy brown fluid. It is important for
you to
recognize each of these steps. As I solder, I watch
the flux as much or more than the color of the silver or the
solder, to
determine how hot to get the piece for
soldering. By the way, I compare this brown syrupy liquid
to glass
enameling. As it cools it gets almost as hard as
enameling glass. It cannot be buffed off. That is why you
need to put
the piece into pickle. The acid in the pickle
dissolves this hardened flux and removes it from the piece.
I will talk
about this more later.
I do not use other fluxes becuase I like the stages that Battern's Flux
goes through while soldering. It makes it very easy for every one,
including beginners, to know just how hot their pieces are, before the
solder flows. I explain this in detail in the Beginning Class.
Information about the class can be found at:
http://www.frii.com/~dnorris/homesilversmithing.html
We will discuss pickle next week.
