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 Post subject: Lap confusion on my first stone
PostPosted: Thu Dec 31, 2020 7:22 pm 
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I took the 2-day beginner's faceting class during the Tucson Gem Show a few years back, and finally bought myself a machine last year. Work and other obligations meant that I'm only now making progress on my first stone, nothing too ambitious, a citrine using Tom Herbst's GeM101 design from his book. I got through most of the pavilion without issue, starting on a 600 grit bonded steel lap, progressing to a 1200 grit, and finally to a 3000 grit lap (I don't have the NuBond resin laps Herbst recommends on hand). I should note I was cleaning thoroughly between steps, rising the stone, dop, wiping down the machine and drain pan, and washing my hands.

I noticed that the pre-polish wasn't a noticeable improvement, the scratches didn't actually seem any smaller, though they were certainly new. I recalled being struck by the difference while taking the class, since the "pre-polish" looked so much like a final polish to my eye, so this was a bit of a puzzler. Herbst recommends an UltraLap for the next step, but again, that's not what I've got on hand. I was gifted a kit with two Gearloose laps, a Zinc+ and a Darkside. Since this is a quartz, and I have a cerium oxide "crayon" on hand (also from Gearloose) I decided to give that a go. I got the lap slightly moist, set it spinning slow, and used the crayon to add a spiral of CeO. I touched the stone to the lap for a moment, brought it up, and the facet I'd thought I was polishing had a layer of black material deposited on it, as did my fingers. I googled around and found a recommendation to scrub and rinse the darkside lap, which did help some. After that I was able to get the P1 facets to look like I recall pre-polish looking, but no better. I was also gifted a BATT lap and several grades of diamond, but have been told that quartz only polishes well with CeO.

For clarity, this is my sequence now:
1. Grind in P1, P2 with 600 grit (Graves #16-586)
2. Cut P1, P2, P3 with 1200 grit (Graves #16-587
3. Re-visit each pavilion facet with 3000 grit (Graves #16-066)
4. Polish each pavilion facet with Darkside charged with CeO

What am I missing?


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 Post subject: Re: Lap confusion on my first stone
PostPosted: Fri Jan 01, 2021 9:53 am 
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Are your bonded steel laps new? If yes, you’ll need to do a break-in , using a piece of CZ of Agate. I would ditch the 3,000 bonded lap , they are known to be quite useless.
I would suggest you to turn your Batt lap into a pre polish lap instead. Charge it with 3,000 Diamond. 8,000 if you intend to cut a lot of hard stuff. You can use your Darkside lap as your only polishing lap, and can charge it with any Oxide, or even Diamonds as long as it is not coarser than 50,000. Just wash well with detergent between polishing agents.
Hope it helps
A very happy new year
:smt002


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 Post subject: Re: Lap confusion on my first stone
PostPosted: Fri Jan 01, 2021 12:30 pm 
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Hi Alex,

skip the 3.000, charge the Zinc+ with 8.000 and go on it directly from the 1.200. Polish with the Darkside. Don't overcharge with the Oxides.

Happy Cutting


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 Post subject: Re: Lap confusion on my first stone
PostPosted: Fri Jan 01, 2021 4:09 pm 
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My suggestion would be if not to late.
Cut your stone with 600.
Charge one side of the batt with 3k.
Cut and prepolish your facet meets in with 3k.
Charge the opposite side of batt with 8k or 14k.
Using a master lap as base as to protect the batt side not being used.
Further your prepolish with the 8k or 14k if needed.
Darkside with cerium with a slow steady drip of water. To polish.
Charge your zinc with diamond 50\60k for the gems, topaz, tourmine, spinel, corundum.
Or follow the former and start buying more laps.
FYI, I do not believe NuBond laps are still available.
My suggestions are not a do all for accomplishing the task but just on this post.

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 Post subject: Re: Lap confusion on my first stone
PostPosted: Fri Jan 01, 2021 6:46 pm 
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Vistar, capudrate, thanks for the advice! My bonded steel laps are indeed factory fresh, I'll try breaking them in a bit before my next stone. It occurs to me the laps I trained on certainly had some wear on them, which must've helped.

It seems like the 3000 grit steel lap was a bit of a foolish purchase, but at least I learned something along the way. I'll see about charging the Zinc+ or BATT for my pre-polish and see how that works out. I haven't been able to google up a good supplier of NuBond laps, though I keep seeing praise for them - is there a go-to supplier in the US for them?

And a happy new year to both of you!


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 Post subject: Re: Lap confusion on my first stone
PostPosted: Fri Jan 01, 2021 7:55 pm 
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I am a lazy guy and try to minimize the number of times I visit each facet.

With Quartz my sequence depends on size.

Under 10 carats.

Preform close so very little to remove when faceting.
Lay the facets on with my 1200, meet points managed here.
Lay a Spectra Ultralap on my master lap, charge lightly with Cerium oxide (speeds it up and leaves a better finish)

Over 10 carats

Preform close
quickly rough in the largest facets with my 360 lap
lay all facets and manage meet points with my 1200
Lay a Spectra Ultralap on my master lap, charge lightly with Cerium oxide

If it is a very big stone I may do a pre-polish on the table with either my 5K D'Lite topper, or a 3K on Zinc + the final polish with the Spectra/Cerium combo.

Success with the Spectra/Cerium polishing is learning to manage speed, moisture, pressure, position on the lap.

Fast, reliable, scratch free, great polish. Repeatable.


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 Post subject: Re: Lap confusion on my first stone
PostPosted: Fri Jan 01, 2021 8:30 pm 
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I'm with you Steve, personnally. But it appeared Alex is working with a limited tool set. Graves topper laps and Gearloose starter kit. I personally use 600 sintered 3k zinc+ if needed , but with quartz it is 8k on the creamway\zinc+ dual lap with a little adding of cerium to the creamway.

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 Post subject: Re: Lap confusion on my first stone
PostPosted: Sun Jan 03, 2021 5:47 pm 
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glhays, I do have a BATT and those grades of diamond, so I could give you approach a try without buying any more laps (for the time being). I was told many times that diamond doesn't work well on quartz/amethyst/citrine, so I hadn't considered it before, but if cerium is the final step perhaps that's what matters most. There are a few videos around on charging BATT laps, that should be straightforward, but I hadn't realized one could charge the two sides with different grades. That makes it much more flexible than I thought!


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 Post subject: Re: Lap confusion on my first stone
PostPosted: Sun Jan 03, 2021 6:49 pm 
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Alexm920 wrote:
glhays, I do have a BATT and those grades of diamond, so I could give you approach a try without buying any more laps (for the time being). I was told many times that diamond doesn't work well on quartz/amethyst/citrine, so I hadn't considered it before, but if cerium is the final step perhaps that's what matters most. There are a few videos around on charging BATT laps, that should be straightforward, but I hadn't realized one could charge the two sides with different grades. That makes it much more flexible than I thought!

There's nothing specific about charging a Batt lap, just apply the diamond across the surface and start using it with the stone your working with, that is "charging". If you want to pre-charge it prior to a stone your working on go for it, just gives you a head start.
Everybody has there own sequence and preferences on how to get it done. Diamond final polish can sometimes be troublesome with quartz but that doesn't mean it is not possible. I have polished many quartz gemstones with diamond and not had a problem, cerium leaves a better looking polish on quartz than diamond, so the suggestions to beginners is to use the cerium and not encounter the possible issues with final polishing with diamond(50k/60k). A Batt lap is a Batt lap on both sides, it seems a shame not to use both sides if you can.

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