Cabbing turquoise

[Lefty]

First attempt at cabbing turquoise. This was the original bit...

It looks nice enough cabbed...

But closer examination shows it has plenty of tiny pits in the surface. I tried polishing with tin oxide after 1200 wet/dry but it undercut pretty badly. Went to the finest bit of paper I have which is 2000 and it took on a dull shine. If I could get about 8000 grit paper it would probably put a satisfactory polish on it. I doubt the stuff would ever take on a highly reflective finish.

Anyone have any tips for working with this material?

 

[Piep]

Turquoise... So beautiful, but such a troublesome stone to work with.
Do you have facebook Lefty? If so, check out the group 'Cabs and Slabs'. There is an incredible amount of experience in that group and - as it has heaps of US members with access to some old stock - a lot of people that regularly post their results with turquoise.

I don't have much experience with it myself, but learned there that turquoise is usually stabilised between pre-polish and the final polish.
My experience with tiger eye has taught me not to work soft (or fibrous, like tiger eye) stones with wet/dry because the debris/dust gets pushed into the stones (or between the fibers). And then after all your hard work, all the pits/porous bits gets filled with tin oxide dust which is almost impossible to remove.

We have 2 pre-polish stations at the club: one with wet/dry laps - 180 to 320 grit - and one with diamond powder charged calico - 320 to 1200 grit. You normally take your stone from pre-form 100 grit diamond wheel to 180 or 220 diamond wheel to 320 wet/dry lap and then to 320 - 1200 diamond laps. I tend to skip the wet/dry step, and make sure I come of the (most worn out) 220 wheel without a scratch and then straight to the diamond powder charged laps. They come of the final 1200 step with a dull shine.

We only have tin oxide on leather laps for the final polish, but I understand from the people in the facebook group that these kind of soft stones take the best polish with cerium oxide, or Zam.

Many of the people posting in the group use a few more pre-polish diamond wheels/laps, all the way up to 10.000 or even 50.000 grit. I have no access to those, but seeing the results some people post, a machine with interchangeable laps, or expanding drum wheels is what I'm going to be looking for when getting my own equipment.

Stabilising is done with a long soak in either epoxy330 in acetone or something called Opticon or Hxtal. That last one is the stuff they use to repair cracks and stars in car windows. The main problem with stabilising turquoise is that the process changes the colour (makes it a deeper blue).

Hope this helps.

 

[Piep]

P.s. gorgeous colour! That's going to be a great stone when you get the polish sorted.

 

[rough2cut]

I polish turquoise with jewellers rouge on a jewellery buffing wheel. Soft stone soft polish.

 

[Lefty]

Thanks guys. I ended up going as fine as I had on diamond paper - 2000 - and it took on a dull shine. Unwisely, I then gave it a second go with tin oxide - that was a mistake. Ripped what posish I had put on straight back off.

I do have some cerium oxide at home but it's in the form of a powder - zam has the stuff impregnated into a kind of buffing wax I think? Is jewellers rouge a similar stuff?

Tonight I'm cutting a slab from a chunk of malachite - am I right to assume that we treat malachite in similar fashion to turquoise here?

 

[Keen Ken]

Hay Piep,
Be careful with any fibrous tiger eye as it was asbestos before it became tiger eye.
Tiger eye is a silica replacement of the asbestos fibers as I understand it.

 

[Piep]

Yeah, malachite is soft! However much more stable then turq. and less pitted, so not so much trouble on the final polish. Be prepared for some (grumpy) feedback if you work it at you club though. The wet/dry wheels will be green when you're done

R2C, you're not the first I've seen suggesting rouge for polishing softer stones. I've recently been on a bit of a quest to find out about different polishing mediums and what to use for which stone on which type (lap/wheel/pad, Leather/calico/felt. Zam/rouge/cerium/tin/other oxides). The only problem I would see with rouge is that it is usually red. You'll end up with red dots all over. There is green rouge as well, but I understand this has a courser grit then the red, which would then lead to a somewhat more dull polish.

What I was trying to find out is if any other oxides have ever been used/experimented with. In powder form with water as a medium and extender, or in wax (like rouge), or perhaps in silicone? I haven't found an answer yet. What I do have is a shed full of oxides and mineral powders. These are normally used as pigments (for paints or make up), but I know some of them are also common as lubricants or UV protection and rouge is made of wax with iron or chromium oxides. I would like to start experimenting with various oxides of iron (black, browns yellows reds, orange), chromium (green like malachite and hydrated chromium is turquoise blue), manganese (pinks, violets), ultramarine (blues), zinc (colourless when dissolved) and titanium (white). Unfortunately I don't have any equipment of my own and can't afford it any time soon-ish, and I don't think they'll be happy at the club if I start doodling colours all over the polish pads.

So far the only thing I can think of, Lefty is to take the more porous stones through to much higher grits on diamond to close the stone up as much as possible and perhaps forgo the final polish if you can reach something accetapble on say 14000 diamond.

 

[Piep]

Hey Ken, Thanks for the advice. I am aware of tiger eye/asbestos and the dangers of stone cutting and generally wear a mask. I have been a smoker for 25 years or so until I quit early this year, so I'm probably doomed anyway.

 

[Piep]

You can use water as a medium and extender for your cerium oxide Lefty.

 

[rough2cut]

Zam fabulustre rouge etc all the same some work better than others some buffs work better than others. But that was how I finished all my trade repair work on malachite and turquoise. Dont worry about the tiger eye its silica now.

 

[TenOunce Tone]

Hi Lefty, I have never worked a stone before but I have been making pens on the lathe, an item I have been using to polish up the pens is called Micro Mesh, it comes in a set of 9 pads that range from 1500 to 12000 grit, they make the acrylic and ca glue pen shine like anything, not sure if they would work on the stone, it may be to hard a material.

You can get a set from an Australian supplier, here is a link to the site, cheapest i have found and postage is not to bad, if you are in sydney, you may be able to save a few dollars on postage. http://www.timberbits.com/micro-mesh-2-x-2-soft-touch-pads.html
and a picture, I am not affiliated with this mob, I am only a customer, I have bought from them a few times and they are reliable.

cheers, Tone

 

[Lefty]

Cheers everyone. I'll give the jewellers rouge a go on the jewellery buffing wheel - I didn't even know we had one until it was pointed out to me last night.

Slabbed and started cabbing the malachite last night - boy is it soft! Just like the turquoise although as Piep says, it doesn't seem to have all the little pits and porous patches the turquoise does. And yes, everything was a nice shade of green when I'd finished, especially me - it would almost be worthwhile taking out a mineral lease on my shorts

Thanks for that link TenOunceTone - I've had trouble getting anything higher than 2000. I'll shortly be getting an expanding drum type cabbing machine so I shouldn't have that problem anymore but I appreciate the link.

Cheers

 

[Lefty]

Finished it off with the rouge - not too a bad a finish. The stuff is never going to glitter with and adamantine lustre because of what it's made of but it glossed up quite satisfactorily. Didn't seem to have any problem with the rouge sticking in the surface.

Started on the malachite. Couldn't get access to the only 360 grinding wheel in the place so I used the 220 - I don't think I would do that again. It was ok at just cutting out the profile but as I started shaping the dome it began to pull little chips out of the surface. 220 is obviously still too harsh for something so soft. Finally I got access to the 360 and found that shaped it nicely without chipping as long as care was taken. I'm even thinking of finishing it off by hand with small pieces of wet/dry.

 

[OwDavid]

It's not perfect, but it certainly looks amazing!!!

 

[AtomRat]

I like it Lefty, I find soft rocks hard to cut..I think I'm just too heavy handed and make deep accidental gouges. I watched a lady at the club grind through lapis lazurite in seconds to a cab

Shape n size looks spot on to me and the reflection looks nice n straight. Set it into a stirling necklace and sell it for $30