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Best way to acheive a satin finish

I tried searching for a modern equivalent online and could only
find one advert for a unit by Walsh Tools here in the UK. 

I use a Graves Cabmate unit for scratch brushing. It’s intended as a
lapidary cabochon cutting unit, so it’s equipped to handle wet work.
The motor is dual speed, and the slow speed works well enough. I’d
prefer it a bit slower, actually, and if it were really needed, some
pulley changes could easily do it. The cabmate spindle easily mounts
a tapered threaded end such as used on buffing machines, and brass or
nickle silver scratch brushes easily mount on this. The fact that the
setup is also just as versatile for more usual cabochon cutting
tasks, or other grinding/sanding tasks, makes it a quite useful
tool. It gets used not just for scratch brushing, but cab cutting,
sharpening certain tools, polishing carbide burnishers with diamond
compound, and lots more.

Sometimes used cabmates show up on ebay, or of course, they can be
purchased new. And I’d guess that there are other multipurpose
cabochon cutting units designed originally for lapidary work that
would equally well handle scratch brushing tasks.

I normally use plain soapy water as the lubricant for scratch
brushing. A traditional lubricant was stale beer, but I’m not sure I
want to stink up my shop with that. Nor am I sure it works all that
much better.

One of the most common uses I have for scratch brushing is when
putting liver of sulphur patinas on silver. Instead of a dull black
patina, scratch brush burnishing gives a nice blue/black gun metal
color and sheen. More durable too, than, the plain unburnished
patina.

cheers
Peter

But wouldn't you describe this surface at matt rather than satin?
Satin is a low sheen... I have always gotten absolutely no sheen at
all with the blaster. 

If you use grit then yes, the sharp edges will give you a mat
finish, but beads, being rounded rather than sharp, give the satin
finish. The grade of bead used is also important; the stuff I’ve used
is not very different to flour and gives a lovely satin finish. To my
mind, a satin finish has no “grain” or “direction” - it has a uniform
"glow" without being shiny. It seems to me that any form of brushing
would leave a “grain” and look slightly different dependant on the
direction from which it’s viewed. That, to me, is not a satin
finish.

Regards, Gary Wooding

Without a doubt. But wouldn't you describe this surface at matt
rather than satin? Satin is a low sheen... I have always gotten
absolutely no sheen at all with the blaster. 

You are right Noel, a sand blasted surface is matt, glass beads
yield a slightly less matt and finer finish. But if you tumble it
with steel shot it becomes satin. I’ve just used a rotary but I
imagine a vibratory or magnetic tumbler would also work.

Polish, blast, tumble… skip a step and you get a different finish
(or a mess)

http://users.gmavt.net/jdemand/rg-hand.html for a picture

Jeff
Demand Designs
Analog/Digital Modelling & Goldsmithing

Like Peter, I love my Cabmate !! it is very versitile, portable and
doesn’t take up much space… I started with only the basic spindle
and used a surplus DC motor with just a simple lamp controller with
a rectifier for full range variable speed. Graves should probably
set up an option up that way.

jesse

Without a doubt. But wouldn't you describe this surface as matt
rather than satin? Satin is a low sheen... 

I’ve kept out of this because of what everyone else has said - there
are many ways to skin that cat. Satin finish can mean any of 100
things - 80 grit sandpaper, 600 grit, wire brushes, satin finish
wheels of all kinds. What Noel says is true, though, in my
experience. Meaning not necessarily everyone will agree, but most
think that way: satin finish is a directional finish, sandblast is a
matte finish, which is non-linear. Not really that important what
you call it, until lines potentially get crossed in communication.

http://www.donivanandmaggiora.com

If you have been following this thread James Miller outlined a method
to achieve a satin finish using a brass scratch unit. The caveat
being one must have a properly finished item before going for the
satin finish.

Peter Rowe suggested the Graves Cabmate for scratch brushing.
Apparently Peter has the two speed motor that is standard. He uses
the slower speed and mentioned that slower might even be better. It’s
not necessary to buy the two speed motor. You can buy a 1725 RPM 1/4
hp motor and use a step pulley using the smallest diameter. I have
arbors set up for polishing stones with polishing laps set up on
either side and I use the bottom section of kitty litter buckets to
catch what gets thrown off the lap. This set up could be used for
scratch brushing by having a feed of soapy water fed from the top.

The emphasis here is the slowest speed. To me that’s what works best
for polishing stone. And it seems for scratch brush finishing.

Some polish procedures cannot be speeded up. There are exceptions:
Matrix opal seems to polish best when it gets hot. For that I use
alumina on a ten inch leather disc fairly far out on the disc with
the disc almost dry. It works for me but I’m sure it’s not the only
way.

Someone once said to me about working stone “can’t you do what you
do only faster?” Sometimes the answer is No.

Another alternative is a flat lap with a rheostat such as the Lee 8"
faceting lap. You can get the exact speed you want. I just wanted to
reinforce the idea, already mentioned, of the slow speed for some
operations.

KPK

Oppi Untracht (Jewelry Concepts and Technology) described a method
of pouring sand or glass beads through a funnel suspended a few feet
above the object to be finished, with a drop cloth or container
below the piece.

Many years ago, before we had a sandblaster, I tried this and it
works surprisingly well.

No racket, no particles floating around the shop, easy to control,
and pretty darn cheap!

Wayne

Meaning not necessarily everyone will agree, but most think that
way: satin finish is a directional finish, sandblast is a matte
finish, which is non-linear. Not really that important what you
call it, until lines potentially get crossed in communication 

I’m with John on this one. There are a hundred ways to get satin,
matte or sandblasted finishes. The key (in my book anyway) is to pick
the method you’re going to use and have a sample out for the
customer. That way, when you are talking about a particular finish
with a customer, you both know exactly what you’re talking about. I
actually have bands out that are partially matte and partially
polished so they can see the differences right next to each other.

Daniel R. Spirer, G.G.
Daniel R. Spirer Jewelers, LLC
www.spirerjewelers.com