Super cerium oxide, French white

[Lefty]

Leah, does this have a particle size equivalent to finer than #14 000? I was hoping to find something around #60 000 to #100 000 particle size equivalent that isn't diamond to try on tiger eye.

[Aussie Sapphire]

No - it is actually about 2 micron but there is more than particle size going on in some of these oxides.

Tin Oxide is also about 2 micron - the #14,000 aluminium oxide is about 1 micron.  But there is some element of chemical polishing going on - particularly with the cerium - so you will generally get good results from either Tin or Cerium in that particle size range if the material being polished is responsive to that oxide polish.

If you want to go that much finer in particle size, the only option we currently have (and would be generally available I think), is Alumina A at about half micron or roughly #60,000.

Available here:
http://aussiesapphire.com.au/index.php?main_page=product_info&cPath=59_90&products_id=1291

Also sometimes called Linde A or Aluminium Oxide A if looking at other suppliers but is all the same if at that particle size range and purity.

Hope this helps.
Leah

[dughug]

I've always had better results using tin oxide on leather as opposed to optical grade cerium oxide (super cerium) when polishing tiger eye. I use a high speed buff and the results are always excellent.

[Aussie Sapphire]

I've always had better results using tin oxide on leather as opposed to optical grade cerium oxide (super cerium) when polishing tiger eye. I use a high speed buff and the results are always excellent.

A good example of how it is more than particle size that influences the results.  Not all polishes work equally on all materials - sometimes a bit of trial and error is required.

cheers
Leah

[MakkyBrown]

No - it is actually about 2 micron but there is more than particle size going on in some of these oxides.

Tin Oxide is also about 2 micron - the #14,000 aluminium oxide is about 1 micron.  But there is some element of chemical polishing going on - particularly with the cerium - so you will generally get good results from either Tin or Cerium in that particle size range if the material being polished is responsive to that oxide polish.

If you want to go that much finer in particle size, the only option we currently have (and would be generally available I think), is Alumina A at about half micron or roughly #60,000.

Available here:
http://aussiesapphire.com.au/index.php?main_page=product_info&cPath=59_90&products_id=1291

Also sometimes called Linde A or Aluminium Oxide A if looking at other suppliers but is all the same if at that particle size range and purity.

Hope this helps.
Leah

There definitely is something going on with Cerium, I can get a better polish using standard cerium on my high speed felt wheel than I can get at the club using tin oxide. On agate and wood. The standard cerium is polishing way beyond 14k as I notice a difference when compared to my 14k diamond wheel. The polish is almost to the level if you wet part of the stone it look the same as the polished dry area. Would changing to high grade cerium make the polish any better?

[Andrew]

Would changing to high grade cerium make the polish any better?

 In short Yes,similar to our Glass Repair professionals almost all use the Higher Grade Cerium for any Polish situation it just works Faster and Better even though the Specs are not much differnt
 I would Leave the Standard Cerium for Tumbling,use High Grade for any Polish situation as even though its Dearer per Gram a Little goes a long way.  

[MakkyBrown]

Thanks Andrew, will have to have a look when we order some more. I use a fair bit of the normal cerium as I loose a lot as the wheel spins fast. Maybe that's why it's polishing so well.
Cheers
Andrew

[Lefty]

I'm currently polishing my first faceted stone - a piece of smokey quartz - on a very thin, floppy round sheet of plastic that sits over a regular lap. I'm told it's charged with ultrafine cerium which is apparently equivalent in particle size to around #100 000. I'm also told you can't buy them anymore.

It's putting an extremely high polish on the gem. I'm aware that the oxides polish with both mechanical abrasion and chemical reaction, I was wondering if finer particle sizes give a finer polish despite the fact that a chemical reaction is also occurring since I have had no success polishing cabs with regular cerium - I've always found that tin oxide has given a good polish on anything quartzy.

[Aussie Sapphire]

While it is possible to source cerium with much finer particle size, it is difficult to get and not often found in lapidary applications. Usually the difference between higher grade and lower grade cerium will be purity instead of particle size. 

This was my understanding of the difference between original spectra (high grade cerium) and plain cerium ultralaps - we have not been able to source these for a while now but spectra were the blue ones and cerium were the brown ones. There were a few different suppliers so possibly some differences in brand (yours may be labelled differently) but I thought that with the ultralaps, it was a purity issue rather than particle size as such.

The purity issue has more to do with presence of other rare earths which are removed to produce a more pure form of cerium - anywhere between 70% up to 99.9% and the reason why the higher grade is generally much more expensive (higher manufacturing costs) but it does give a better result.

Going much finer in particle size will slow down polishing - the main reason we went with 2 micron for our commercial scratch repair customers - they were getting excellent results with the high purity product but it was significantly faster with the 2 micron grade compared to the 1 micron (which in their opinion did not give a better result - just a slower one).  These differences are probably a little exaggerated when doing plate glass windows compared to small faceted stones but could be one reason why most lapidary suppliers tend to stick with the 1-2 micron range for cerium as it just works well.

Cheers
Leah

[Lefty]

Thanks Leah. The one I am using is the blue one - are they not manufactured any longer?

Also, is it possible to mix the oxides with anything other than water so they are flung off the pad/wheel less? They are pretty inexpensive compared to diamond so I'm not worried about the cost, I was just thinking there might be less mess/contamination. I have used the tin oxide exclusively on a homemade carpet disc on the little old Hall faceting machine but it is pretty slow speed compared to the Cabking and I'm wondering if the same stuff applied to a polishing pad on the cabbing machine would give a faster result. I just don't want the medium sprayed around the place owing to the much faster rotation of the cabbing machine polishing pads.

Can oxides be mixed with vaseline/lanolin or will that interfere with the chemical action?

[Aussie Sapphire]

I dont think that manufacturer is producing anymore - we have not been able to get them for a few years now.

No - you cannot mix an oxide polish with a oil-based extender - unlike diamond, they are not compatible. We had a customer once who could not get his Darkside lap to work at all but later found out he was mixing the cerium with oil - got great results once he switched to water.

You can choose to mix them into more of a paste with water compared to a thin slurry but unfortunately, a little mess is inevitable when using oxides.  One of the reasons why the BATTStiks have been so popular - could maybe try this but probably better on a harder type pad (eg. cowhide leather) with a light spray of water to keep damp as required.

Remember that the Lortone spin on end plates are compatible with the Cabking so you can try a few different pads to see which works better for you - canvas (Cabking version) or use felt/leather with or without rubber pads underneath on a Lortone end plate - you can use soft suede leather or cowhide (smooth or rough side) so it does give you quite a few options to choose from.  Some soak up the polish more and others have a more unyielding feel.

Others may also have some suggestions.

cheers
Leah