Polishing Information?

[jBailey]

Hi, All, from the West,

Guess I'll dive in to help jump-start some action, here.

I would love to learn what the guys on the European side of the pond are using for various materials - and the reasons for selections, if anyone wants to share this?

I would also love to learn what are your practices concerning grit to cut; and grit to pre-polish, prior to polishing. Are folks going from 600 to polish, or if not, what are the intermediate steps?

Having asked those questions, here are my habits:




My mentor taught me, and I practiced this polishing arrangement for some years:

- Most stones hardness < 5: typically cut on 600 and then right to polish with Alumina on Tin or Alumina on Wax

- Most stones hardness 5 - 7.5: typically cut on 600, and pre-polish on Raytech Newbond 600 (red), then polish with Cerium Oxide on various laps, usually Plexiglas

- Most stones 7.5 - 8.5: typically cut on 600, and pre-polish on Raytech Newbond 600 (red), then polish with Alumina on Tin or Micron Diamond on BATT

- Stones 8.5 and up: typically cut on 600, and pre-polish on 1200 on copper, then polish using Diamond on BATT

- Troublesome stones: Alumina on Wax


Based on experimentation and personal preference, I now use a very different arrangement:

- Stones hardness 4 - 8.5: typically cut on 600. Some stones will go right to polish; some pre-polish on Raytech Newbond 600 (red); some pre-polish on 1200 on copper; and some pre-polish on 6 micron Diamond in a carrier medium on countertop-material lap. The choice of pre-polish depends upon the hardness of the stone, size of the faces, and orientation with respect to troublesome things like cleavages that may exist. I polish all stones in this range using Micron Diamond in a carrier medium on Wizard Lap, Corian, Formica, or Himacs (the later three laps are common countertop materials).

- Stones hardness 8.5+ typically cut on 600, and pre-polish using 6 Micron diamond on Copper or on BATT, then polish using Micron Diamond on BA5T or BATT.

- Very soft or troublesome stones still polish using Alumina on Wax.

Good meets to all!

[kking384]

Hi J

I always cut to 1200 then pre polish at 3000 on copper and finish with 60,000 on tin.

I only use diamond powder as thats all ive learnt so far.

mind you ive been cutting for only a short time.

Kevin

[jBailey]

Hi, Kevin,

That was a fast reply! Great to meet you.

You're really pre-polishing fine before polishing - Are you doing competition cutting?

Also, you said "always" - what materials are you cutting with that strategy?

John

[kking384]

so far ive cut the following

fused quartz
jewellers silica
cz
amethyst
peridot
iolite

even faceted sodalite into shapes for the wife.

and yes i entered the UKFCG this year.

[graham scarr]

hello, thought I would join the fun and put my tuppence worth in.

I usually rough out with 220, course cut with 600, fine cut with 1200, prepolish with 6 micron on wax (sometimes get a polish on corundum and topaz), and polish with 1 micron on tin or perspex - calcite to corundum. Oxides seem to be much more messy so hardly ever use them since obtaining the tin lap - worth every penny. I cut 5mm to 25mm width.

[jBailey]

Kevin wrote that he's using 60k on Tin for everything - and his list of materials runs from ~5 to ~7.5 or so.

And, now Graham also says 1 micron on Tin for everything from 3 to 9 hardness. Interesting prepolish with 6 micron on wax. I'm in agreement, also regarding oxides - messy - and troublesome to maintain the proper level of lubrication.

I like micron diamond better, but there can be mess and lubrication issues there, too. What are you guys doing for a carrier base or for lubrication for your micron diamond?

I'm using oil when working on metallic laps, and I'm using a lubrication-embedded compound that I developed when working on other types of laps.

So, that's two votes for "diamond all" - Is that the standard on your side of the lake, or is there a significant contingent of Oxide proponents?


Graham - Would you share some information about that wax lap you're using for pre-polish (if it's not proprietary)? - For instance:

- Did you make your own wax lap or do you have a source for them? Can't find one in the 'States, and my attempts to make one have produced a smelly kitchen and a riled-up wife! <laugh>

- I assume it's a pretty hard wax?

- How do you prevent facet rounding?

- After using wax for pre-polish, it's interesting to go back to Tin for polish. What started you with that strategy?

Wonderful visiting with you guys - Really enjoying it, and looking forward to reading more.

[Paul Wheaton]

Hi John

What do I polish with?
Mainly 50k on a Batt lap for any stone harder than 7 this seems to work most of the time. I do get some facets on synthetic sapphire that need a few tries, reversing the direction but come up with a good polish in a few seconds.
On these materials, Beryl, Spinel, Sapphire, Topaz, CZ, YAG and GGG I rough in at 360, cut at 600, pre polish 3000.
Occassionally when I have the won't polish 'Orange peel' problem I recut on 1200 and polish from there. This seems to work but the polish can take some time to acheive. <Don't try pressing harder- I embedded a large synthetic ruby in a BATT lap by pressing too hard. Fortunately BATT laps are double sided!>

Softer stones: more varied approach, usually I try the BATT first on a small test facet to see if it will give a good polish.
Quartz gives the best result with CeO,
Zincite with 50K on BATT.
Feldspar polishes well with either CeO or 50K.
Tourmaline varies usually CeO or Linde A (Raybright B), it will polish on 50K but it doesn't seem as good.
Glass, I include Moldavite, Apache Tears and synthetics CeO on Perspex
Fluorite: carefully, directional, CeO on Perspex at low speed.
Calcite I've only done a couple but keeping the lap speed down and cutting on 600, pre polish on a worn 1200 gave a good result with CeO

As for lubricant, usually water for polishing a slow drip to keep things from drying out.

When charging the BATT lap, until it is well broken in I use a synthetic food safe slicer oil. (Used in Butchers to maintain their machinery. It doesn't thicken up or break down over time and if I get covered in it, it will wash out.) Once in use I use water - until the next recharge.

Nice to see a board on this side of the world!

Paul

[graham scarr]

Wax laps a la merrill murphy for prepolish (polish sometimes). Basically he uses furniture polish - carnauba and beeswax on perspex. A thin smear wiped around the spinning lap and left to dry followed by another layer. Dont apply it too thick, flatten any lumps by running a blade across it while spinning and polish with a cloth when dry. Rub the diamond paste all over the lap applying a bit of pressure and it is ready. I use 6 micron diamond which I buy ready mixed from manchester minerals and a water drip. The lap improves with use and lasts quite a while if you are careful not to get any gouges in it. Merrill murphy wrote an article about it in stonechat 44 in 2002. Although he recommends cleaning a worn out lap with alcohol before rewaxing, I find that just adding to the old one works well.

[jBailey]

Thanks for sharing guys,

I understand about that orange-peel and the long-time polishing from 3k or 1200. Corundum (and sometimes Spinel) seem to under-cut or pit when using those grits, especially on the resin-bond laps, and polishing takes longer. I've found really good luck using 3k on BATT or copper for prepolishing those materials. No undercutting.

Thanks for the Zincite info - I've some rough, but not cut any yet. I'll keep that in mind!

I'm surprised by the Tourmaline on CeO - I never had luck with that. In the past it was Alumina on Tin, and now diamond-in-carrier compound on plastic.

You must've hit the directions on that Calcite. IMX, any cutting on a surface finer than 600 invites it to cleave on a small-scale, resulting in deep pitting of the stone - and perhaps shards of calcite embedded in the lap. I ruined a newbond this way!

Your lubrication strategy for the BATT is new to me - It sounds good, and I think I'm going to try it. Where do you find the food-safe oil - at grocery store?

Graham - Thanks for the info on the wax lap. I'm going to look up the stonechat (I have the CD) and give that a try soon. It sounds pretty flat, due to thinness of the wax, and with a light touch, perhaps the facets don't round too much? I think this sounds like a great lap for troublesome stones - Have you ever tried alumina on this surface?

Thanks for sharing stuff guys. I think that cutting is usually pretty straightforward, but as my mentor told me once "Polishing is Voodoo"...

Have a great weekend!

[paul Stansfield]

Hi John and the rest of you guys,

I cut mainly hard stones (corundum, quartz, tourmaline, beryl) and over the last few years have moved over from a mix of polishes (alumina, Cerium oxide etc) and now only use diamond powder.

My cut is as follows for most stones:

v rough 100 grit
rough and cut 600
pre-polish 1000
polish - 14-20000 diamond powder on a couple of last laps I have set up.

Anything that proves a bugger to polish or for corundum I will pre-polish out with a 3000 lap and maybe go from 14-60,000 to get rid of the adamanitine smear finish.

Got some other ideas as I have lots of polishing laps (lucite, tin, ceramic) but other than being intrigued by reading sites that swear by tin (personally all I seem to do is 'gouge' the lap out ), frankly I just can't be bothered to spend hours 'playing' when I know the last lap will do everything I need it to.


Good to see a forum kicking in!

Cheers

Paul

[jBailey]

Hi, Paul,

I'm interested in your 1,000 pre-polish. What kind of lap do you use for that - Is it a metal-bond, a resin-bond, or did you roll your own with copper and loose diamond - what?

This is a great discussion, and I'm learning loads. Thanks to all.

John

[paul Stansfield]

Hi John,

The 1000 laps I use are all metal bonded crystalite un-backed ones (8") used on a blank.

I have a old one (4yrs, maybe 20 stones later) which is non agressive and I guess probably now cuts a 2000 grit finish

And a new one which cuts a bit faster but leaves a slightly rougher finish.

I use the new one for aquarmaries, quartz and tourmaline currently as they are OK to go straight to polish after this and for courundum I use the old one (unless I am really keen and use a 3000, but its the time man....................... ) as it gives a finer finish and saves me time on the polish wheel (I'd say saves me x3 as corundum is hard and a finer pre-polish/final cut means just less to polish out)

A really good web site by someone who seems to have tried everything under the sun is the Gram faceting one

http://www.faceters.com/askjeff/answer53.shtml

He has loads of experience and i think in general I would say have a read and give the stuff a go.......does not always work as personal preference is a factor in all choices but great background info in my opinion.

Cheers

Paul

[Brad Amos]

I have been faceting for only a few years, but it may be useful to pass on my experience. I use mainly CZ and corundum.
My chief method ( based on advice from serveral experts in the USA and UK) has been to shape corundum with 1200 and 3K Crystalite steel laps with water. I try to avoid using coarser laps because of the deep damage. I then used to go from 3K steel with water to 50K with a little oil on a Batt lap for the final polish. I have learned to clean up scrupulously, including under fingernails and with a thorough wash of the splash guard, stone and dop, before moving to the Batt.
I charge the Batt with the 50K plus a little woodwind instrument oil, which has no smell, and put a fine drop of WD 40 on if it seems to be drying up, and I run the Batt very slowly. Dressing with a norbide stick seems to keep the Batt in good condition.
This method served me well and gave a polish good enough to be praised by the judge in the UKFCG competition. However the progress from the grey facet produced by the 3K Crystalite to the polish was sometimes very slow with corundum (e.g. 20 min for one facet). I was counting the endpoint as the disappearance of the last bright dot from the facet, when the cleaned surface was viewed with the 10x loupe under a powerful fibre lamp. I asked Doug Morgan and Jim Finlayson how to speed things up and have finally adopted a copper lap with a 5 um diamond grit, purchased from Jim, and used with oil. This seems to bridge the gap very well and has speeded up my polishing stage. Sometimes the 5 um grit seems to bring me almost to a final polish, which I don't understand.
I have little experience with soft stones, except for some natural zircons which polished quickly and easily with aluminium oxide in water on a pure tin lap. I have never used a wax lap.