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Author Topic: Help, does Topaz twin like quartz?  (Read 1054 times)

FlashGP

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Help, does Topaz twin like quartz?
« on: April 06, 2018, 07:28:25 AM »
A few years ago I had trouble polishing quartz.  The 8k prepolish left a mat finish.  I was told at the time it was probably twinned.  I ended up buying lughtning laps to cut and polish it.

I was told it was probably a twinned crystal from Kingsgate.

I have now run into some topaz that behaves the same way.  8k diamond on zinc won't prepolish.  Where the surface starts to shine it seems to crumble away.  It happens on every pavillion facet.

It cant be subsurface damage as I preformed with a 1200 and faceted using 3k on zinc.

The lightning laps and a darkside with Linde A batstick polish, but are hellishly slow.  8k on copper with water almost beats the issue but it scratches badly.
Yours Sincerely
Flash (Gordon)

Bucket

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Re: Help, does Topaz twin like quartz?
« Reply #1 on: April 06, 2018, 12:20:34 PM »
You should try and find the cleavage plane on topaz before you cut it. You then should cut it if memory serves me right, with the table at about 15 degrees from the cleavage plane. The reason is if you try and polish parallel to the plane, it will react in a similar way to what you're describing. It sounds like you are trying to polish the along the cleavage and hence small bits are breaking off and hence the difficulty to polish. I can usually get a polish with 8k on a pewter lap if the stone is oriented correctly.
Common sense isn't exactly common

FlashGP

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Re: Help, does Topaz twin like quartz?
« Reply #2 on: April 06, 2018, 01:54:12 PM »
Hi Bucket

I have tried to irient the clevage plane about 10 to 15 degrees off the table.  But this is happening on all pavillion facets.  I was expecting a clevage pkane problem to manifest itself in only 1 or 2 facets.

Regards
Gordon
Yours Sincerely
Flash (Gordon)

Rusted

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Re: Help, does Topaz twin like quartz?
« Reply #3 on: April 08, 2018, 10:06:12 AM »
You could try using very light pressure and lubrication, I use Inox but probably any of the WD40 type things would work. Spray it on and when the lap starts to get mucky just a quick wipe with a tissue and another spray. If you don't like it it washes off fairly easily.

I have had a few synthetics do the same thing but its usually just one facet that happens to line up with the way material was deposited on the boule, the above method usually gets me out of trouble.

FlashGP

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Re: Help, does Topaz twin like quartz?
« Reply #4 on: April 11, 2018, 07:27:22 AM »
Thanks Rusted I'll try a heavier lubricant like sewing machine oil.  I have been using snake oil which is thinner than wd40.

I am having more success with 8000 on copper now I have sanded it to a shiney state with a worn 1600 lap.

My worn 3000 lightning lap works as well but is much slower.

Polishing with Aluminium Oxide Batt Stick on a Darkside works but is too slow to use at this stage.

It seems like the surface crumbles at the edge of the plane being cut.  But for it happening on all facets I would have thought I had oriented the stone wrong.

Regards
Gordon
Yours Sincerely
Flash (Gordon)

Buch Metter

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Re: Help, does Topaz twin like quartz?
« Reply #5 on: April 11, 2018, 08:13:23 AM »
I think you are spending too much time on a sh...y piece of stone Flash, but the best part is the inherited experience and knowledge that you get from doing it.
Some crystals just don't behave like a normal piece of crystal should, particularly in my case with some zircons.
The topaz that comes from Flinders Is is another torment, very fractious material.

FlashGP

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Re: Help, does Topaz twin like quartz?
« Reply #6 on: April 13, 2018, 06:02:48 PM »
My wife said something v similar.  The 3k lightning lap seems to work but is almost as slow as Linde A on a polishing lap.  But for it polishing with Al2O3 I would start wondering if I had a diamond.

It also has a fine red needle inclusion.

I'll sand my laps and have one last go to see if I can beat the B......

Regards
Flash
Yours Sincerely
Flash (Gordon)

FlashGP

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Re: Help, does Topaz twin like quartz?
« Reply #7 on: April 15, 2018, 09:58:53 PM »
It looks like the needle in the topaz is tin and the tin content may be affecting the prepolish.
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Flash (Gordon)

Buch Metter

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Re: Help, does Topaz twin like quartz?
« Reply #8 on: April 16, 2018, 07:18:08 AM »
I have never had any experience, that I know of, in polishing a tin included quartz crystal, so please document your practices and results for the rest of us, Flash.

FlashGP

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Re: Help, does Topaz twin like quartz?
« Reply #9 on: April 16, 2018, 05:56:04 PM »
Hi Buch


This crystal is Topaz included with tin.  The advice I have received so far is to start again with a different crystal.

Im getting a concave facetor and may have a go with that as it will be experimental and I won't worry about meet points etc.

When I have this trouble with quartz, I switch to water as the lubricant.  It requires clean laps and doesn't seem to work for harder materials, CZ etc.

Regards
Gordon
Yours Sincerely
Flash (Gordon)

Buch Metter

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Re: Help, does Topaz twin like quartz?
« Reply #10 on: April 16, 2018, 08:32:16 PM »
Pita stones do require a deviation from the norm, the thing is to find the deviation that works such as a slow drip of water every 3-4 seconds on the oil and diamond charged lap.  I rarely use anything other than diamond for my polishing.  Cerium, Alox, Chromium went by the wayside some time ago, though a Spectra lap with a 100k diamond spritz will come out from time to time.

FlashGP

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Re: Help, does Topaz twin like quartz?
« Reply #11 on: April 17, 2018, 05:53:51 PM »
I haven't tried a diamind spectra lap.  It looks like I'll have to experiment some more.

The 3k lightning lap helped but was too slow so I didnt try the 14k lightning lap, maybe I should.

Regards
Gordon
Yours Sincerely
Flash (Gordon)

mehoose

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Re: Help, does Topaz twin like quartz?
« Reply #12 on: July 12, 2018, 09:58:40 PM »
Gordon, all I can think of to suggest is a very cheap method that we used for comp stones at the club.That was just a disc of thick perspex, scored the surface, applied pink cerium, firm pressure and worked a treat. In fact it worked a treat on quartz as well..just doesn't look as flash as the good gear. ;)
Keep em comin!!!

FlashGP

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Re: Help, does Topaz twin like quartz?
« Reply #13 on: July 20, 2018, 07:20:54 AM »
Thanks Mehoose,

I gave up on trying to complete the stone for a comp.  Instead I cut it on a concave machine using 3 in 1 oil from bunnings as a carrier which solved the problem.

My Facetron spins 3 or 4 times faster than the Gemmaster, Drabsch and Hall machines I have seen.  Slurries dry out too quickly at 200+ rpm and cause scratching.

Clarry Trevena thought my speed controler was going, but it has been this way since brand new so I guess it is the machine.

So far I have found that at speed quartzes generally like water as a carrier/coolant, topaz, sapphire and CZ like an oil.  I usually use a really thin snake oil for this, but for the topaz I ran two thin lines of 3 in 1 oil across a makeup removal pad using my oiling serynge I oil my machine before applying a few drops of snake oil.  Thus cured the problem.

I use the makeup removal pad to continuously clean swarf from the lap.  This speeds up cutting and reduces scratching.  They work far better than toilet paper and drop less lint.

Anyway, which club are you in?

Regards
Gordon
Yours Sincerely
Flash (Gordon)

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