Polishing Troubleshoot

I have been having problems with the polishing tasks on each cut I do. Main problem is the hours and hours of polishing compared to the the faceting tasks which usually only takes an hour or two tops. (depending on complexity of course) Some stones have taken me literally days to polish to a scratch free eyeball standard. Is this normal or are my expectations to high?

My usual technique is as follows:

• Finalize the cut on a 3000 grit diamond lap (brand new)[/*]
• Then drop to 12,000 grit diastick on 4 inch BATT, [/*]
• Then to 60,000 diastick on the other side of the BATT. [/*]
• 100,000 only for stones I really like and not often as I have to borrow a mates lap for that one.[/*]

My polishing lap is well looked after and all care is taken to avoid contamination.

Will increasing the lap size and speed reduce my polishing times?
I am using some pretty ancient gear. An old graves with a two speed motor. I am spoilt for choice between snail and turtle speed. To make matters worse I only have a 6 inch BATT lap (new). Does lap speed significantly improve polishing times or does it reach a point where it is counter productive?

I will be replacing the bearings in the main shaft and motor and I am considering changing the pulley ratios underneath to increase the speed. Is this actually going to help or am I just going to make an unruly old machine even more finicky?

Any advice would be greatly appreciated.

What are you cutting?

Regardless I'd use 3000 diastick on BATT and then straight to 100K. Unless quartz. 3000 prepolish then CeO on darkside. Although darkside will possibly drive you nuts. It's a love hate thing. Can try CeO on perspex. Others reakon Zirconia is better than CeO but gave me endless scratching.

Also make sure facet aligns with polish lap. Marker pen on facet then swipe.

Shouldn't take too long, seconds to get a good X10 polish.

Quartz is renowned for being temperamental.

For quartz, beryl, feldspar, 3000 on BATT then CeO on Darkside.
For garnets/spinels, alumina on darkside.
For the rest, 3000 on BATT and 60K on BATT (but I don't like the last one, I am thinking about investing in something else for polishing).

Others reakon Zirconia is better than CeO but gave me endless scratching.

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I've had a similar experience with it. It does seem slightly faster but that doesn't help when it just keeps scratching. CeO is still my go to for quartz and I have had good results with it on Perspex, regardless that others insist the facets will be rounded. If there is any rounding with mine then it is extremely minor at worst. I mostly now polish quartz with CeO on a Matrix.

I have a Darkside but haven't used it yet and have heard bad reports about it after buying it. I saw a faceting academy bloke polish the table of a good-sized stone in a few seconds with Chromium oxide on a Darkside.

I have a BATT but it is little-used at present. I have found the Matrix to be the most versatile polishing lap thus far and has worked well for me on things a soft as feldspar and as hard as sapphire and seems equally happy with diamond or oxide. Typemetal and tin alloy both work well but have a tendency toward scratching. Others will have had different experiences

I guess the different results I've had with Ceo and ZrO could be the application method. The CeO is in powder form and I apply it mixed with water in a spray bottle, just the tiniest spritz is all that is necessary, a few drops really. The ZrO I have is in the form of a stick. A little household ammonia heavily diluted in a spray bottle with water might break down the binding material but I've found it still scatches. Might be less prone to scratching if it could be applied the same way as the CeO.

I have a Darkside but haven't used it yet and have heard bad reports about it after buying it. I saw a faceting academy bloke polish the table of a good-sized stone in a few seconds with Chromium oxide on a Darkside.

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I certainly don't think of it as user friendly. I've had mine for a couple of years now and I have only recently got it to perform as the maker said it would. When you first use it, it will produce a black gunk and scratch. Scrub it under the tap. Repeat again and again. Once the gunk stops the scratching seems to stop. It's early days but mine seems to be behaving. Using the marker pen to make sure it's aligned to the lap helps with an even polish.
Although I reversed lap direction the other day and the scratches immediately returned.

Both my CeO and ZrO are now in stick form.

Mr Magoo said:

I have a Darkside but haven't used it yet and have heard bad reports about it after buying it. I saw a faceting academy bloke polish the table of a good-sized stone in a few seconds with Chromium oxide on a Darkside.

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I certainly don't think of it as user friendly. I've had mine for a couple of years now and I have only recently got it to perform as the maker said it would. When you first use it, it will produce a black gunk and scratch. Scrub it under the tap. Repeat again and again. Once the gunk stops the scratching seems to stop. It's early days but mine seems to be behaving. Using the marker pen to make sure it's aligned to the lap helps with an even polish.
Although I reversed lap direction the other day and the scratches immediately returned.

Both my CeO and ZrO are now in stick form.

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The surface of the Darkside is probably impregnated with polymer swarf from machining, causing agglomeration scratching. I guess I'll get round to using it one day - after scrubbing the hell out of it first

My Darkside performed well with cerium from day one.
But as Lefty said, very little polish compound is necessary, I apply CeO in a diluted waterspray, and I use a stick for alumina, but I use very little, I just touch the lap with it for every new facet.

I am still looking for a good solution for diamond polish, the Batt is a bit slow, it is more a prepolish lap.

The surface of the Darkside is probably impregnated with polymer swarf from machining, causing agglomeration scratching. I guess I'll get round to using it one day - after scrubbing the hell out of it first smile

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That's exactly what I think is happening. There in no individual component that is harder than the quartz, Not even the CeO. But I struggle to believe that so many have problems with it and the blame is attributed to contamination. Yet the same people have no 'contamination' problems on other laps.
And since the rationale of how the CeO can polish quartz, how can one so easily explain the scratching.
But I can say once it works, it works well............ More often than not anyway.

Anyway I have to get it to work. I've got about 2000 cts of Bolivian Ametrine and Amythst to get through.

You're gonna be busy, that's a lot of carats

Thanks for the reply's. I am using a 3000 diamond lap. Perhaps the grit is not as accurately graded as a 3000 diastick. I have considered the possibility that the lap itself is much coarser than it should be. Possibly more like a 1600. This would explain why it takes ages to remove some of the scratches. Has anyone encountered this before?

Most of my cutting material are topaz, smokeys and citrine. I want to nail down an effective polishing method before I attempt more valuable stones.

Would CeO be more effective on a topaz than diamond?

SneakyCuttlefish said:

Thanks for the reply's. I am using a 3000 diamond lap. Perhaps the grit is not as accurately graded as a 3000 diastick. I have considered the possibility that the lap itself is much coarser than it should be. Possibly more like a 1600. This would explain why it takes ages to remove some of the scratches. Has anyone encountered this before?

Most of my cutting material are topaz, smokeys and citrine. I want to nail down an effective polishing method before I attempt more valuable stones.

Would CeO be more effective on a topaz than diamond?

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CeO doesn't have much effect on topaz SC, not that I've experienced. My best results polishing topaz have been with #100 000 diamond on a Matrix. If you were to use an oxide for topaz, it would be Alumina A (B is too fine in my experience) not Cerium.

Your problem I think is much more likely to be agglomeration scratching during polishing rather than contamination. It used to drive me crazy as well. A couple of things I have found - and others will have had completely different experiences - is that (1) diamond polish seems less prone to scratching when using oil-based extenders such as WD-40 rather than water-based.

(2) Scratching often seems to be the result of either too much polishing compound on the lap (use sparingly) or a build up of swarf (clean the lap thoroughly and re-charge)

(3) The composite-ceramic Matrix lap seems to experience significantly less scratching problems than either typemetal or tin alloy. There would be other metal laps that I haven't tried that might also be less prone to scratching.

I'm polishing a sapphire now and I'm not that happy with the finish. You can't really see the very fine cat's hairs with the naked eye but they are there. The last stone polished on the same polishing lap was another sapphire - it finished up very nicely in the end but had a lot of bad orange peeling at the start. I'm wondering if that was the source of a build up of corundum swarf. I think I'll meticulously clean the lap off, re-charge and do it again.

Alumina on topaz is not faster than diamond, so it is not an improvement (contrary to garnets and black spinels, which polish very well with alumina).

GallicProspector said:

Alumina on topaz is not faster than diamond, so it is not an improvement (contrary to garnets and black spinels, which polish very well with alumina).

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Yep. I like the finish left by oxides but still found diamond faster on topaz. Maybe if you want to be really pedantic you could give it a final tweak with alumina after polishing with diamond.

I had no success polishing garnet with alumina until it was pointed out that I was using alumina B (0.05 micron) which is very much finer particle size than alumina A (think it's 0.3 micron). I then tried A which seemed to work a lot better.

GallicProspector said:

My Darkside performed well with cerium from day one.
But as Lefty said, very little polish compound is necessary, I apply CeO in a diluted waterspray, and I use a stick for alumina, but I use very little, I just touch the lap with it for every new facet.

I am still looking for a good solution for diamond polish, the Batt is a bit slow, it is more a prepolish lap.

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That's my point. Some just don't have an issue off the bat.

Did you get that black cr@p so many have mentioned?

I know it wasn't the amount of CeO I was applying. I'm applying more now at a time than during attempts to get the scratching to stop before. When I first cut and used a Perspex lap I enjoyed cutting quartz using CeO. And they came up good. I only wanted to get a flatter facet.
Now it polishes nice and fast. The only thing that changed is the black muck.

For a polish lap try 100K PCD Blakstik on a Matrix. Fast and will shift meets. I also like for Corundum 100K on Tin.

SneakyCuttlefish said:

Thanks for the reply's. I am using a 3000 diamond lap. Perhaps the grit is not as accurately graded as a 3000 diastick. I have considered the possibility that the lap itself is much coarser than it should be. Possibly more like a 1600. This would explain why it takes ages to remove some of the scratches. Has anyone encountered this before?

Most of my cutting material are topaz, smokeys and citrine. I want to nail down an effective polishing method before I attempt more valuable stones.

Would CeO be more effective on a topaz than diamond?

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Using 3000 plated laps is generally thought of as asking for trouble (I've never used them) partly because of the reasons you have said. Try 3000 on BATT, Copper or try one of R2C's laps.

Unfortunately a polishing technique for a smokey won't work on a saph. Synthetic stone can be fun to play with to check your skills although no skills acquired regarding orientating the rough .
Try a nice big Emerald cut. Simple but not. http://www.shell-lap.com.au/shellla...pidary"&category_2="Synthetic Faceting Rough"

Using 3000 plated laps is generally thought of as asking for trouble (I've never used them) partly because of the reasons you have said. Try 3000 on BATT, Copper or try one of R2C's laps.

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That's an interesting one Mr Magoo - for cutting in facets it's all I've ever used in #3000 pretty much and had good results (though I have played around with other stuff). Fast to cut, cheap to replace, does a good job, negligible risk of contamination, never given me trouble. On the other hand, #3000 on a Batt will give a better-looking surface for polishing than a plated one in my experience.

But I haven't learned the technique that users of loose #3000 grit must use - I assume you tell when the facet is done by feel. On the plated lap, I can cut very accurately by sound, listening for when the faintest tic-tic noise just stops. The sound of cutting with loose grit on a thick lap is much duller and harder to pick when it has just stopped. How do you approach cutting in the facets?

I haven't used a 3000 plated and I am only repeating what I have read. So I guess if it ain't broke etc. etc.
I think the problem is from cheap manufacturers using badly graded diamond grit and also problems relating to the surface plucking of chunks of diamond as they age. Probably be aware of it.
I've always used 3000 (or 8000) on copper or a BATT.
For me it's just a case of feel, listening and looking. Experience also. I used to over cut like no tomorrow. You have to be aware once you recharge it will cut like a knife. Even wiping it down of swarf makes a huge difference.

That's just my opinions.

Some really great knowledge being spread around here. Thanks all.

Mr Magoo has convinced me to try cutting with a BATT. I started out by listening to the sound to gauge when a facet is done but now I mostly eyeball each facet as I go. Measure twice, cut once kinda thing, so I guess the lack of sound won't be hard for me to adjust to.

How do you clean the swarf off when using a diastick? I have found it very hard to wipe it of with a dry cloth. (especially if I have over-charged it) So normally I will dab a bit of shellite onto a paper towel and run it across a spinning lap. Takes it all straight off really easily. Just have to recharge more frequently. Is this OK to do or am I just making the job harder for my self?

How do you clean the swarf off when using a diastick? I have found it very hard to wipe it of with a dry cloth. (especially if I have over-charged it) So normally I will dab a bit of shellite onto a paper towel and run it across a spinning lap. Takes it all straight off really easily. Just have to recharge more frequently. Is this OK to do or am I just making the job harder for my self?

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The way I do it is a few drops of 'Diamond extender' (can use baby oil but it is a bit thick) or WD40 on the lap, rubbed in, spun up and wiped with a piece of tissue. You don't need to get it spot less (the tissue will pick cr@p from the lap for a life time) and make sure the lap is not dry. You need a bit of lube but at the same time you don't want it aqua planing on excess lube.

The removal of swarf is to remove the gunk of ground quartz from clogging up the cutting diamond that has hopefully jammed itself into the lap surface. IIRC the BATT is supposed to work so well (apparently) as it has a crystal structure that allows a large amount of diamond to work it's self into the surface.

Remember the BATT will suck up a lot Diamond to start off with. So it will take a bit of Diastik. Also there are other options than Diastick. I used to just buy the grit and mix it. I used Vaseline as the carrier but now I think it's a bit heavy.

As for charging a lap. I'm not getting involved in that. So many variations. All right and all wrong.