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 Post subject: How to polish a rough stone by hand?
PostPosted: Sat Apr 10, 2010 8:39 am 
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Hello, I know next to nothing about stone cutting and polishing.
However, I'd like to know what kind of stuff I need so to be able to polish a rough stone by hand in the field, the faster the better.
I mean in case a stone looks interesting but it's just to difficult to see clearly inside of it because its surface is too uneven (in such a case I could use immersion technique, however immersion liquids are unpractical to carry in the field). Another possibility is that I have a crystal which facets can't be read on the refractometer and I want to make one of these smooth enough so I can get an accurate refractometer reading.

So, what do I need for quickly opening a polished window inside a rough stone (manually), and how do I proceed?
Of course I want to avoid damaging the crystal doing so.

Thanks


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 Post subject:
PostPosted: Sat Apr 10, 2010 12:17 pm 
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You can try wet/dry automotive sandpaper USE WET WITH WATER. Or copper electronic circuit boards that you have previously imbedded with diamond grit, USE WITH WATER OR OIL. Either way will be very slow.


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 Post subject:
PostPosted: Sat Apr 10, 2010 2:46 pm 
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I'd get a couple of different grits in in those diamond pads used for knife sharpening and as lorne144man has said, acouple small pieces of copper plated circuit board material. Rough cut the surface with 600 and 1200 grit and then a bit of 3000 diamond paste on that copper plated board. That's good enough to see inside a stone as well as get a decent R.I. reading. If you're really picky you could go to 14K. I just tried this sequence with a garnet and some stationary wetted laps and it took a couple of minutes to get a large semi polished window. It's a little slower on sapphire, but not enough to cause a time concern. The only problem is in keeping the facet flat, (I think that it would be good enough for an R.I. reading though.

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 Post subject:
PostPosted: Sat Apr 10, 2010 6:03 pm 
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Quote:
Rough cut the surface with 600 and 1200 grit and then a bit of 3000 diamond paste on that copper plated board


I don't understand what you're suggesting here.

Why use copper plated electronic board rather than a piece of wood or else?

Are you suggesting that I cover this board with some kind of 600/1200 mesh sand paper? Or are you talking of a different kind of abrasive (abrasive paste? abrasive powder?)? I don't know what you mean by "grit"

How should I stick the abrasive stuff to the board?


Last edited by cascaillou on Sat Apr 10, 2010 6:09 pm, edited 1 time in total.

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 Post subject:
PostPosted: Sat Apr 10, 2010 6:08 pm 
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cascaillou wrote:
Quote:
Rough cut the surface with 600 and 1200 grit and then a bit of 3000 diamond paste on that copper plated board


I don't understand what you're suggesting here.

Why use copper plated electronic board rather than a piece of wood or else?

Are you suggesting that I cover this board with some kind of 600/1200 mesh sand paper? Or are you talking of a different kind of abrasive (abrasive paste? abrasive powder?)

How should I stick the abrasive stuff to the board?

The theory of the copper lap is in play I think. Copper starts soft and then hardens with the diamond in the surface. So, rolling diamond into copper should give a longer lasting tool. Wood softens with use and water. Wood is easier to work with making a tool.


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 Post subject:
PostPosted: Sat Apr 10, 2010 6:14 pm 
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what are you all refering to as 'grit' material? Is it abrasive powder that has to be imdedded inside the coper plate, or abrasive paste that is rubbed over the copper plate before use, or abrasive paper that will have to be stuck on the copper plate?

If powder abrasive, how am I going to get it imbedded inside the copper plate?


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 Post subject:
PostPosted: Sat Apr 10, 2010 6:15 pm 
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I'm suggesting that you use something like the attached picture for the initial grinding. These are diamond plated steel sheets attached to a handle and are used for sharpening knives.
Image Do a search for "diamond plated hand files" or knife sharpener and lots of this stuff will pop up.


These only go so fine and you'll need something finer to approach a polish. That something finer could be a copper plated circuit board material. The copper will hold 3000 and up diamond grit better than wood and will stay flat much longer. I would suggest diamond paste rather than dry diamond particles because it's easier to apply. Oh, embedding diamond in the copper is easy, just smear some on the surface and use it. Finer grits will embed thenselves pretty quickly.

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Last edited by michael_e on Sat Apr 10, 2010 6:19 pm, edited 1 time in total.

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 Post subject:
PostPosted: Sat Apr 10, 2010 6:18 pm 
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Quote:
I would suggest diamond paste rather than dry diamond particles because it's easier to apply.

I know nothing about polishing techniques. You mean that I will rub some abrasive diamond paste over the coper plate, and that this paste will stick all over it, so then I can rub the copper plate covered with paste against the stone to polish it. Is that it?


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 Post subject:
PostPosted: Sat Apr 10, 2010 6:22 pm 
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cascaillou wrote:
Quote:
I would suggest diamond paste rather than dry diamond particles because it's easier to apply.

I know nothing about polishing techniques. You mean that I will rub some abrasive diamond paste over the coper plate, and that this paste will stick all over it, so then I can rub the copper plate covered with paste against the stone to polish it. Is that it?


Yes, that's about it. Just put those files on a flat surface, add a bit of water and rub your stone against them. Same thing for polish and the copper plate, except you have to add the diamond paste. I'd rub the stone against the stationary plates because I think it would be easier to get a flat facet.

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 Post subject:
PostPosted: Sat Apr 10, 2010 6:27 pm 
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ok, I understand. Looks simple.

should work better than my verneuil boule and spitted saliva :lol:


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 Post subject:
PostPosted: Sat Apr 10, 2010 6:34 pm 
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a few more details:

let's say I want to open a polished window on some rough corundum.

Is it possible to do it two steps? I mean: start with low mesh diamond file, and then directly go for high mesh diamond paste?

For instance, can I start with 500mesh file, and then finish the polishing with 3000 mesh paste, or do I necessarly need an intermediary 1200mesh file in between these two steps?

ps: I don't know if what I just asked is very understandable...


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 Post subject:
PostPosted: Sat Apr 10, 2010 9:51 pm 
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cascaillou wrote:
a few more details:

let's say I want to open a polished window on some rough corundum.

Is it possible to do it two steps? I mean: start with low mesh diamond file, and then directly go for high mesh diamond paste?

For instance, can I start with 500mesh file, and then finish the polishing with 3000 mesh paste, or do I necessarly need an intermediary 1200mesh file in between these two steps?

ps: I don't know if what I just asked is very understandable...


It will all work, it's just a matter of time, dependent upon hardness.. make sure you clean off the stone when you switch grits, you don't want to contaminate you copper sheets.

Avoid 1200 on corundum, that causes 'orange peel effect'. A heavy loading cuts faster than a light one.

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