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Polishing flat surfaces


#1

Dear Orchid Members, I would like to hear what process others follow
in polishing metals. I seem to be having more difficulty than I
think I should be in achieving a mirror-like finish on flat
surfaces. Even small flat surfaces. I am working with sterling
silver. If the surface has any curvature to it, I have no problem.
If it is flat, I have a hard time eliminating all scratches without
introducing other surface imperfections. I have read in all of my
jewelry books and they all kind of gloss over this without going
into much detail. The process I have been using is as follows:
file (where needed), 400 silicon carbide sandpaper (SC), 600 SC,
1500 SC, fine Cratex rubberized wheel on my flexshaft, tripoli on 4"
stitched muslin buff (3450 rpm motor speed), red rouge on 4"
unstitched muslin buff (same motor speed).

If I omit any of these steps the results are not satisfactory. I
have tried using the red crocus cloth instead of the 1500 SC but end
up with deeper scratches (BTW does anyone know the grit equivalent
of red crocus cloth? Just curious). If I do not use the fine (light
blue) Cratex wheel I end up with scratches I cannot easily remove
with buffing. I have tried using a bristle brush and tripoli on my
flexshaft to remove small scratches but the fine Cratex wheel works
better for me. I have gotten better results using the 4" buffs than
with 6" buffs (slower surface speed). I try to constantly change
directions when buffing but this is not always possible when buffing
around other components, such as a bezel. I have also tried ZAM and
Fabulustre but have not achieved any better results than using
tripoli then red rouge. I just don’t think it should be this
difficult. I don’t remember having this much trouble way back in my
high school jewelry class (many moons ago!). I think we generally
used steel wool back then. I haven’t tried this yet. What processes
do others use? What could I be doing wrong/better?

Thanks in advance for your feedback, Dale

P.S. - Just a point of interest on another deox sterling alloy. I
recently had some castings done and they talked me into using a deox
alloy. When I asked what the alloy consisted of, they said this
particular alloy was 92.5% silver, 5% germanium, 2.5% copper.


#2

Dale, There is a great tool that I seldom hear mentioned on this
list. A split lap machine. I was trained on one years ago while
working at a jewelry manufacturing facility in Fla. and have been
using one and introducing people to them ever since.

The tool is a basic 1/2 hp motor mounted so that the spindle is
pointed directly at your face. Check out a picture in a tool mag and
it will make more sense. The laps are either GMX styles that are
very aggressive grinding tools or the polishing laps made from
pressed wool. Both the GMX and wool laps come in a variety of sizes,
grits and degrees of hardness. The working surface of the lap is the
underside of the lap, the surface facing away from you. This is the
reason for the splits in the lap. The light mounted above the work
surface allows you to “see through” the lap while it is running at
full speed. You can see the surface of your piece as you work it.

Well, with this tool and a bit of practice you can take a small
flat surface from rough casting to high polish in three steps in
about three minutes. The process creates such a flat surface that
it is often necessary to soften the edges to make a piece wearable.

The steps are simple. GMX lap with 80 or 120 grit, diamond hard
felt lap with yellow rouge and a light final polish with muslin
buff using your preferred rouge. Seriously, it is that simple.

I really can only guess why this tool is not utilized by more
jewelers. My guess is that it is an intimidating tool that takes
practice and training. There is no training manual that I have seen
and there are so many tricks involved that it would be terribly
difficult for someone to just buy one and pick it up on their own.

If you are interested in hearing more, let me know and I will try to
help.

John Sholl
Littleton, Colorado


#3
achieving a mirror-like finish on flat surfaces. 

Hi Dale,

In order to get a perfect (or very good) polish on a flat surface,
you’ve got to think “lapping.” Lapping is grinding/sanding/finishing
against a flat surface. Start with your abrasive papers glued to a
firm, flat surface. I use a block of UMHW plastic 1" thick, but plexi
or even real glass would work. It’s just got to be very flat.

When you get to the finishing stages you can use tripoli and rouge
on a dense fabric mounted on a flat surface. If you want to use a
motorized polishing solution, you have to use a hard felt wheel,
often referred to as “rock hard.”

They make a felt “split lap” specifically for this purpose. It’s
flat on one side with splits from the edge toward the center so you
can see through the lap as it rotates and see your work as you hold
it up against the flat side. Ususally requires a special buffer for
this kind of lap, but you may be able to find a way to improvise.

Hope this helps,
Dave


#4

These are sanding techniques that work for me with silver.

First, avoid adding scratches. Keep silver sheet stock wrapped in
paper. Work on soft paper towels, cloth or chamois, or use masking
tape to protect the surface.

Second, use a strong light and magnification.

Third, only sand where there are scratches. Don’t sand the entire
surface just to remove a few scratches. Start sanding the deepest
scratch with 600-grit and move back to 400-grit or 320-grit sanding
paper, if the finer grit doesn’t remove the scratch. Only sand the
whole surface at 600-grit or finer. Sand in the direction of the
scratch, or no more than a few degrees of either side. Sanding
perpendicular to the scratch only deepens it and/or removes too much
metal. (I have seen people sand sheet down to foil by cross-hatch
sanding.) Also, see the last paragraph in the Short Course in my
web site for more

Last, consider the beauty of curved, textured or satin finished
areas as a way to minimize large expanses of flat, high polished
areas. As a design issue for silver, ask how the recipient (store
clerk, customer, friend) will maintain the high polish, or how will
your jewelry look after a month of normal wear?

Good luck. Sanding a flat surface to a high polish is a very
difficult challenge.

Nancy
www.psi-design.com


#5
 I use a block of UMHW plastic 1" thick 

Just to correct myself… that should be “UHMW” - Ultra High
Molecular Weight, which is a very dense, somewhat malleable plastic
similar in characteristic to Delrin. I was able to pick up a couple
nice blocks of it, inexpensively, from the odds and ends pile at
Cadillac Plastics store here in town.

All the best,
Dave
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#6

A couple of things I learned: 1. If you put too much pressure on the
piece while buffing, you are apt to introduce scratches. 2. If you
scrub too hard to get the rouge off, you are apt to introduce
scratches. Someone advised me that you need an ultrasonic to drop
the piece into to remove rouge. Since I could not afford that, I
found a baby-soft toothbrush and that seemed to work okay. 3. I now
texture most of my work because it looks more finished and elegant
to me, and scratches don’t show unless they are deep.

J. S. (Sue) Ellington


#7

Dear Dale, I have had some success overcoming these problems. I make
silver cufflinks and other pieces of silver jewellery which commonly
have flat surfaces and have found that finishing on the wheel often
does not do them justice. The way that I get around this is to use
wet SC sandpaper held on a clean surface to grind a perfectly flat
layer onto the surface. I usually take this to 1,200 grade. I then
take a clean piece of scrap cloth, stretch it over a wooden board
(pine works well, make sure it has a lightly sanded surface),
impregnate it with white diamond polish (similar to tripoli, but cuts
faster and brighter) and place the face to be polished on to it and
rub vigourously for a minute or so. Then repeat the process using a
different cloth and rouge, which can be cut with a bit of paraffin to
help it get into the cloth. A bit old fashioned, but surprisingly
quick and gives a good finish. The other way to get around this is to
break up the surface - lightly planishing it works well, as does
strategically placed hallmarking (my favourite - see examples at
http://www.cpenner.freeserve.co.uk/cufflinks.htm). Good luck, and I
look forward to hearing what everybody else has to say. Chris Penner


#8
   I really can only guess why this tool is not utilized by more
jewelers. My guess is that it is an intimidating tool that takes
practice and training. 

John, I think it’s a little bit like wondering why more people don’t
drive very high powered cars on a race track for fun. Split laps
are wonderful tools, indeed, and I love the things for what they do
well. But I’ve also seen people out of practice or less experienced
with then reduce a fine piece of jewelry to scrap metal on a split
lap so fast it wasn’t’ funny. Well, wouldn’t have been funny even if
done slowly. But these tools are not only very efficient, they also
require some skill and a high level of attention. Let your eye
wander for a moment, and you can peel off an amazing amount of metal
that you didn’t wish to remove…

And hers’a question for you and others using split laps. I’ve seen,
and have also used, both the flat side of split laps, and the
slightly tapered side. I find both sides useful, for various
different types of lapping. but i’ve always been curious whether one
side or the other was the traditionally preferred method. Intuition
would have suggested the flat side is the usual working side. But I
often find the tapered side not only a little easier to use, but
because the angle of the work is slightly more level, I find it
easier to see what i’m doing when working the tapered side of the lap
(which means the flat face is facing me, of course). I’ve known
professional polishers who fall on both sides of the issue. How
’bout you? Anyone else?

Peter


#9

Hi Dale, As soon as you try to use any form of wheel you will destroy
a flat surface - particularly on a soft metal like sterling silver.
Achieving a ‘black’ polish on a flay surface is one of the most
difficult operations in metalwork and requires absolute cleanliness.
The way I do it on hardened steel for watch parts (the same procedure
applies to any metal) is to use sheets of perspex (acrylic) of around
6" x 4" and 3/16" thick with diamond paste. Each grade of paste has
its own sheet which is kept in a zip-top bag whenever it is not
actually being used - that is it is not allowed to even sit on the
bench while another grade of polish is being used. I usually start by
removing any fine file marks using a 45 micron grit and you must keep
going with this until a very even grey matt surface is produced. The
action is to put a very small amount of diamond paste on the perspex
sheet and to rub the surface to be polished on this paste, moving it
all over the sheet to prevent any depressions being created in the
plastic. Now, the polish is wiped off the perspex and tis is put away
in its bag and the workpiece is thoroughly cleaned by washing and
then finished off in the ultrasonic. If even one speck of the 45
micron polish is left on the metal it will scratch the next stage!
Now the process is repeated using 30 micron paste, then 15 micron, 6
micron, 1 micron and finally 1/4 micron. At each stage, every trace
of the previous grit must be removed. As small scratches like to hide
in the ‘grey’ surface of the first couple of stages, it is quite
likely that you will have to go back and repeat these to get rid of
all marks. When a good polish has been achieved like this, you can
add the final lustre by burnishing the silver using jewellers rouge
on a hard, wooden-backed, felt buff stick. As I said before, you will
not be able to maintain a really flat surface using any form of wheel
and particularly with cratex wheels which have a variable composition
and cut more or less depending on how the abrasive is distributed
through the composite.

Best wishes,
Ian
Ian W. Wright
Sheffield, UK


#10

Dear Dale, I have had some success overcoming these problems. I make
silver cufflinks and other pieces of silver jewellery which commonly
have flat surfaces and have found that finishing on the wheel often
does not do them justice. The way that I get around this is to use
wet SC sandpaper held on a clean surface to grind a perfectly flat
layer onto the surface. I usually take this to 1,200 grade. I then
take a clean piece of scrap cloth, stretch it over a wooden board
(pine works well, make sure it has a lightly sanded surface),
impregnate it with white diamond polish (similar to tripoli, but cuts
faster and brighter) and place the face to be polished on to it and
rub vigourously for a minute or so. Then repeat the process using a
different cloth and rouge, which can be cut with a bit of paraffin to
help it get into the cloth.

A bit old fashioned, but surprisingly quick and gives a good finish.
The other way to get around this is to break up the surface - lightly
planishing it works well, as does strategically placed hallmarking
(my favourite - see examples at
http://www.cpenner.freeserve.co.uk/cufflinks.htm). Good luck, and I
look forward to hearing what everybody else has to say. Chris Penner


#11

I like using the beveled side of the lap. Using the beveled side,
one can usually avoid hitting the edges of the work. Although this
doesn’t result in a perfectly flat facet, the edges can come out
razor crisp because all other forms of polishing that I am aware of
will tend to attack the edges first. I can’t even imagine why someone
would use the flat side of the lap as the side of a hard felt lap on
a regular polishing lathe can provide equal results. I might also add
that although the jewelers that I have seen use the flat side of the
lap may have produced a decent job, the jewelers that used the
beveled side seemed to do a little better.

It comes down to this. The flat side of the lap will always attack
the edges first and produce a very slightly convex surface. The
beveled side can be controled to the point that one never touches toe
edges, thus producing a slightly concave surface with sharper edges.


#12
Someone advised me that you need an ultrasonic to drop the piece
into to remove rouge. Since I could not afford that, I found a
baby-soft toothbrush and that seemed to work okay 

Try Rio Grande’s Buffing Compund Remover. It’s a concentrate you
mix up, works great, I recommend it t everyone.

Elaine Luther
Chicago area, Illinois, USA
Metalsmith, Certified PMC Instructor
Studio 925; established 1992
@E_Luther


#13

Peter,

Oh yeah, the split lap can do a number on a piece of jewelry really
fast. Have you ever jammed your finger against the edge? They
remove skin really fast too.

I have several laps for several different applications and I do have
one that uses the tapered side down. It is medium hardness lap which
is the softest split lap. I have ground the working surface into a
curved surface and while I don’t use this lap very often it is great
for curved (concave) surfaces such as side of shanks.

The guy who trained me was a partially retired career polisher from
New York city. Can you imagine polishing for fifty years? He did do
amazing work with the split lap. He had a collection of wooden laps
some with knife edges! those really scared me but now I regret not
learning how they were used.

Here are some of the tips he passed on to me.

-Always use leather pads to hold your piece while lapping. The
pieces get really hot really fast and you should be concentrating on
the work and not searing flesh.

  • All sorts of jigs can be made from old ring clamps and spring
    loaded clothes pins.

  • Never use greasy compounds. These compounds will get absorbed into
    the lap and cause the felt to swell thus ruining it. Don’t let it
    get wet either.

  • Constantly clean and true your lap with a dressing stone. You
    can’t make a flat surface with a rough one.

  • When the lap is worn down eliminating the splits simply cut them
    deeper.

  • Black out the top surface of the lap with permanent marker. The
    contrast helps you to “see through” the lap at speed.

-Practice practice and practice some more. My first lesson was to
facet the edge of a nickel. I still use that as a demonstration.

John, I think it's a little bit like wondering why more people don't
drive very high powered cars on a race track for fun.

I like this analogy but I must point out that if I could buy a high
powered car for the same price as a split lap machine and lap (under
$500.00) I would be on my way to the track tomorrow. For a lesson
of course.

John Sholl
Littleton, Colorado


#14
    Intuition would have suggested the flat side is the usual
working side.  But I often find the tapered side not only a little
easier to use, but because the angle of the work is slightly more
level, I find it easier to see what i'm doing when working the
tapered side of the lap (which means the flat face is facing me, of
course).   

In my experience the Flat Lap works easiest with the tapered side
facing down , the angle presented to my hands provides a more easily
controlled surface and control is “the name of the game” in flat lap
usage , in addition I find the work more visible too .Excellent
results with the flat lap , in my experience , becomes a matter of
feel [ the relationship of the piece to the wheel via the hands ]
over visibility , it takes practice . I teach co-workers to use the
lap with scrap jewelry , you can really impress with the speed you
can change the metals surface .

Mark Clodius


#15
   - Black out the top surface of the lap with permanent marker.
The contrast helps you to "see through" the lap at speed. 

Ya see, that’s what I, and others, love about Orchid. I’ve used
split laps for years, but here’s a really good and simple idea I’d
not thought of. As I get older and more experienced at this, the
percentage of postings that give me new info may diminish some, but I
still never stop learning from this forum.

   -Practice practice and practice some more. My first lesson was
to facet the edge of a nickel. I still use that as a demonstration. 

that IS a good demo. You could advance to doing a Canadian nickel,
which is already facetted on the edge, requiring the victim ( mean,
student), to retain the exact positions of the original tiny
facets…

        John, I think it's a little bit like wondering why more
people don't drive very high powered cars on a race track for fun.
I like this analogy but I must point out that if I could  buy a
high powered car for the same price as a split lap machine and lap
(under $500.00) I would be on my way to  the track tomorrow. For a
lesson of course. 

Me, I think I want to hold out for the space ship at that price.
(I’m thinking I’d love to find a Sanders Rapid Toolmaker type RP
machine, at the price of an ordinary ink jet printer…)

Peter


#16

Thank you all for your responses so far. (You need not stop now,
though). I have heard of the split lap as a possible tool, but I
have also heard that they require much practice/skill to master
without, as Peter says, reducing a fine piece of jewelry to scrap
metal. Are these laps used with rouge or tripoli or which
compound(s)? I have tried hard felt knife-edge wheel with tripoli
(on a practice piece of silver) but the results were not good. I
pretty well trashed the surface and could not get a consistent
finish across the whole surface.

I will try some of the methods proposed but it seems some of them
may be a bit difficult to do around a bezel or in tight quarters
between other non-flat components. The surfaces I have trouble with
are not necessarily large, just flat.

I know that using the Cratex wheels will not result in a perfectly
flat surface but for the smaller surfaces this is not that critical
or noticable as long as the polish is high and consistent and the
surface doesn’t vary too far from “flat”. Using the Cratex wheels
is also a painstaking and time-consuming process which requires some
practice/skill also to not do more harm than good. It’s just that
this is what I have found to be most effective so far. I have found
I must frequently dress these wheels with some fine emery paper to
remove the built-up metal residue before this begins to cause
grooves. (I seem to be able to prevent any emery particles from
remaining on the wheel).

I am still curious through what grit sandpaper does everyone
normally progress before proceeding the buffing wheel? I am also
still curious if anyone knows what grit the red crocus cloth is
equivalent to?

I could use a tool that provides a narrow strip (~3mm) of sandpaper
on a firm (and also narrow) “stick” where I can easily and
frequently advance the sandpaper to a fresh surface. I currently
hold small pieces around various shape needle files and such to
access small spaces. Does anyone have a better method? I guess I
should have piped up with this during the thread on “tools I’d like
to see”.

Thanks again,
Dale


#17

Dale, Several bench jeweler I know use “sanding sticks,” which are
12"?? X 1"?? X 1/8" ?? (dimensions are a guess, I don’t have one at
hand.) You could make them by cutting lengths off a yardstick and
wrapping fine sandpaper or crocus cloth around them (abrasive side
out.) The edge is close to your 3mm. As you ‘use up’ the abrasive,
just peel off a layer. This MAY be a hint that EVERYONE on the list
knows about, but maybe not David Barzilay, Lord of the Rings


#18

One item that comes in handy is the silicon abrasive pins. I shape
the tip and am able to access small spaces.

Jon in Montreal


#19
  ... Using the Cratex wheels is also a painstaking and
time-consuming process which requires some practice/skill also to
not do more harm than good. 

True enough. The smaller the tool or wheel, the harder it is to
keep the surface even and flat. By the way, if you’re actually using
Cratex brand wheels, you’d be pleased with your results if you try
the various types of silicone rubber wheels instead. Cratex rubber
wheels are optimized for working steels in tool and die work, and
aren’t as good on our soft metals. I especially like a rather soft
and flexible gray colored wheel carried by many dealers, that’s rated
as a soft coarse grit, but the finish you can get with it, due to
it’s softness and flexibility, is quite good. Much nicer feel to
them than the kinda rough feeling cratex wheels.

   I am still curious through what grit sandpaper does everyone
normally progress before proceeding the buffing wheel? 

Depends on the work. Sometimes I stop with 220 grit, on gold when
I’m in a hurry and things are easy to lap. On platinum, I prefer to
go to around 400 or so. But the Gesswein platinum polishing
compounds are so effective that sometimes I’ve gone to them straight
from a fine cut file or a relatively coarse paper like that 220, or a
#3 emery, which is pretty coarse… And where I work, most of use
just use that #3 emery on a majority of ordinary surfaces that don’t
need higher refinements before polishing. This may be due to the
fact that we’ve got a full time polisher who’s quite good, already,
at removing a good deal of metal in his quest for the perfect polish.
Given his sometimes heavy hand, going to a higher grit than that
isn’t always needed… but if you’re doing your own polish, and
working on really precise things that need to keep that precision,
you may want to go all the way to a 600 grit. You don’t normally
need to go higher than that for most work, even with platinum.

 I am also still curious if anyone knows what grit the red crocus
cloth is equivalent to? 

I don’t think it really equates. It’s finer than most actual grits,
and the abrasive is rouge, so the particles are producing a
different type of mark that abrasive particles of harder materials…
But if I had to guess, I’d guess at about 1200 grit or so. Maybe
higher.

   I could use a tool that provides a narrow strip (~3mm) of
sandpaper on a firm (and also narrow) "stick" where I can easily
and frequently advance the sandpaper to a fresh surface. 

You can buy cool little plastic sanding sticks that are color coded
so you can keep track of which grit is on which. They’ve got a
spring loaded end, and use a closed loop of abrasive cloth, around a
quarter inch wide or so. which goes end for end around the stick,
being held in place by that spring tension. As the strip wears, you
just move it around the loop. One end of the stick comes to a narrow
profile, so it gets into tight spaces.

You can also buy, usually from tool and die places, abrasive tapes.
These are like sturdy round or flat cords, coated with abrasives.

And if you want really flat narrow little abrasives, you’ll get
longer life from the paper or cloth if you glue it to a stick or your
choice. The 3M sanding films are very durable, and glued to narrow
plastic or metal strips make fine long lasting tools.

And one other favorite tool, long unavailable, but now again
available, are the “scotch stone” abrasives. Also labeled “water of
ayre” or something of the sort. They’re like a soft slate or
something, available as sticks from an 18 inch square and up. Use
them with water. The ends are easily shaped, and you just rub it on
the metal where it quickly takes the shape of the surface you’re
working on, and with water, also is quite effective at removing
metal very evenly and gently.

Allcraft carries these little gems.

Peter


#20

Like most of the other respondents, I use a split lap, though I’ve
not tried using the beveled side.(I will now though, thanks.) The
most important thing is to have it mounted correctly. If it is
threaded at all unevenly, it will rock, and you’ll never get a flat
surface. I’ve had my best results with a diamond hard lap, rather
than rock or flint hard. I bought mine from Gesswein, and have not
seen them anywhere else. The compound which I use, which I discovered
accidentally, is Allcraft’s, for stainless steel, which seems to be
different than other steel compounds that I’ve tried. (I once had to
polish titanium, and forgot to change the wheel when I was polishing
gold.) It cuts quickly and leaves a mirror finish. For small areas,
I use a flat hard felt wheel on the flex shaft. By using the top and
bottom, rather than the edge, it can be turned into a mini lapping
wheel. Hope this helps. Susan