I am having a terrible time trying to polish a silver band bracelet.
For the life of me, I cannot rid it of drag lines when I polish! I
have removed all of the fire scale, sanded to a 1200 grit surface,
and tried everything from bristle brushes to buffs to felt laps.
(Each after re-sanding the piece). Ideally I would take a rock hard
lap with a fresh surface to the piece, but cannot due to its
construction. I have a bit of experience polishing, and never
experience this frustration with gold. Any tips for me? Thanks.
Erica Duffy
Dear Erica, If you can share a few more details on your polishing
method, it will help any of us help you. By drag lines do you mean
drag lines of media that is layed on the surface of the metal while
you polish, or actual grooves made in the metal?
Once you get the surface evenly to 1200 you really shouldn’t have
any problem buffing the metal to a mirror finish if it’s sterling.
What media you are polishing with and in what order? Tripoli, white
diamond, rouge? Maybe the wheels are the problem (of course, I
assume you are not contaminating one on top of the other). Too
thick, too thin, too old, caked on with media? Pull out the file
card and clean them up. The angle at which you hold the object
against the wheel is important, as you may well know. Are you
approaching the wheel with the same consistent motion? I put the
object gently against the wheel and pull up, over and over. Maybe
the environment? My wheel is outside under cover (I’m in So. Cal.)
and I know when I polish in the middle of the day in the middle of
the summer, the process is slightly different. The media melts all
over the place! When it’s cold out (it’s all relative, folks) the
media likes to cake.
Give us more, and will get it all polished up! Take it from what my
friends call me, an anal polisher.
Kay Taylor
Erica, Is the bracelet made from stock that you purchased or did you
roll out your own sheet? It sounds like you could have microporosity
in the silver .I would loupe it and see if you can notice any
microporosity. If it is microporosity you can burnish some of it out
if it with a burnisher you can buy from any jewelry supply store. It
is a little tricky to do but try it. Also do you have any scrap left
over from making the piece? If so try buffing that to see if you get
the same effect. I would also recommend putting new muslin buffs on
your machine and using Tripoli on a stitched buff and red rouge on an
unstitched loose buff. Your buffs may have been contaminated. Also
try buffing in the opposite direction of the streaks using easy
pressure. Regards J Morley Coyote Ridge Studio
The bracelet is made from 16g stock sheet from Hauser and Miller,
and is about 3/4" wide. When polishing silver, I generally start
with a lap and grey star. I then go directly to a yellow treated
mulsin buff with tripoli and/or grey star, or a bristle brush. I
don’t generally clean when going from grey star to tripoli, but
always clean when going to rouge or back to grey star (so as not to
contaminate my rouge buffs nor felt laps).
I think my method in terms of direction is okay–I work back and
forth at 90 degree angles and try to polish as gently and as little
as possible. The drag lines are grooves in the metal. I actually
always have this problem, but it’s not usually so obvious as the
pieces are smaller and a perfect finish is not as imperitive. Most of
my laps and buffs are relatively new. I did take some time to clean
and redress them–although maybe I need to start with a new set.
Someone suggested that I put lamp oil on the piece while polishing.
Have you heard of this method? I am a bit concerned that it will
ruin my buffs. Any help you can give me would be great. Thanks!
A few years ago I did a lot of charms and had a similar problem. I
called my supplier and they explained to me how they make the sheet.
All use what is called a continual cast process. The metal is melted
and forced through a die. Tthe metal is then immediately rolled
through the rollers. That is how they described it to me, hopefully
I have explained it adequately and accurately. Anyway, the process
makes for pretty large crystal formations and if you do very little
supplimental work to the metal, polish it and then look closely you
can see a slightly uneven surface; this is due to the nature of the
crystal structure of the metal.
With this system of creating sheet, they seem to get what I call,
though it is probably not accurate “twisted crystals”. They are not
so much pits as knotted areas that polish out at a different rate
than the area around them. The only way I was able to fix this was
to be very aggressive on those areas and swirl the item relative to
the buff so that I didn’t polish in any one direction for more that
a second or two. Eventually you polish through the “knot” and can
move on to the next area. It is a pain, but it’s the price we pay
for low(er) cost production sheet with no pits/cracks.
I hope this is helpful. If I have gotten any of the metalurgical
theory or production technique wrong please correct me, I’d love to
know if I’m accurate or not.
Larry
I think my method in terms of direction is okay--I work back and forth at 90 degree angles and try to polish as gently and as little as possible. The drag lines are grooves in the metal.
What about changing the angle to 45 degree !! !! alternating
\ /
It was suggested to me as a way to polish over solder joints so that
you don’t end up with a groove in the joint. I also use it when i
am polishing flat surfaces to avoid drag lines.
Hope that helps
Brigid Ryder
With this system of creating sheet, they seem to get what I call, though it is probably not accurate "twisted crystals". They are not so much pits as knotted areas that polish out at a different rate than the area around them.
Metals we use form crystals in the cubic system. Fully symmetrical
in all directions, and capable of distortion in any direction with
working/rolling, and during annealing, such distorted crystals relax
and reform smaller, grains with similar universal symmetry. Twisting
metal, or it’s crystals, does nothing different from any other form
of working it.
Continuous casting methods of sheet production produce a continuous
strip shaped ingot, unlike traditional methods of casting brick sized
ingots. The traditional method usually employs a step where they
mill off the exposed surfaces of the brick, to remove surface
irregularities. The result is then rolled into sheet, and given the
larger size of the “brick”, it goes through a lot more reduction. so
traditionally rolled sheet may end up with slightly more uniform, and
smaller, grain size. Continuous cast sheet, on the other hand,
doesn’t need the surface milled off, since the machines give
uniform smooth ingot surfaces as it casts them, and the process
reduces the tendency for components to segregate out from the center
to the surface, as can happen in the large brick sized ingots. So in
theory, continuous casting should also give a very uniform even raw
metal to feed to the rolls, and uniformity of the alloy composition
will be superior. But, if in the process, inclusions form, such as
oxides mixed into the melt, or carbides (some metals can combine
with carbon, such as from graphite melting crucibles, to form
carbides, which show up as hard knots in the metal), then these can
end up on the surface of the sheet metal, behaving just as you
describe. The hard bits you found are probably not just distorted
crystals of good metal, but rather inclusions of a different
material, either oxides, bits of foreign material entirely, or
carbide inclusions, or something of that sort. The highly automated
nature of sheet production from continuous casting means, among other
things, that there is not so much human observation of the sheet as
it’s rolled to it’s final form, so defects, though rare, are more
easily not noticed by the processors.
Peter
Could the brushes be stiff enough to make the lines? I use Bobbing
compound ,Graystar and Zam, I do fabrication not casting and rough
with my silver as I work on it.
Marilyn Smith