Need help with Cerium Oxide polish problem!

[Tom in SW WA]

Hi Folks,

I'm in SW WA state, and am blessed to have access to some great
Agate collecting sites.
We've been tumbling for a couple of years, and use Lortone
equipment. I'm currently running a dual six pound drum tumbler.
Anyways, everything is fine until I get to the final polish stage.
The first material I used was a white Cerium Oxide (CeO) powder. It
worked quite well, and I was able to capture the slurry and reuse the
polish.
A little got lost each time I polished, and I was forced to buy
more. The store I bought the material from then sold me an off white
CeO.
The first time I used this, something didn't seem quite right.
There was almost a film left over, and the quantity of material
salvaged was way below par.
I use a chunk of lye soap dropped into each step of the process
(including final polish) to break up the surface tension.

The second use totally destroyed my pellets, and turned everything
into a gummy mess: The pellets all clumped together, the drum and
rocks needed a very agressive cleaning, and I was a very unhappy
camper.
I finally got through all that junk, and went to an Aluminum Oxide
polish.
That went fine, but as I ran out of it, I wanted to go back to a
decent CeO again.
Bought some on line that was guaranteed to be 99%... Lo and behold,
on the first use I have the same gummy mess that I got earlier after
two uses.
What the heck am I doing wrong? Did I just get a bad batch of CeO
that isn't as pure as it's supposed to be, is the CeO or an impurity
in it reacting with the soap to form an insoluble metal Stearate
(similar to hard water and soap reaction)?
Many Thanks for any help that any of you can give me!

Best Regards, -Tom

[docone31]

Cerium Oxide is not white. It is an off flesh orange. I have a feeling the white was something else.
I use Cerium Oxide a lot. I facet gems, and use it on my final laps. I use it either completely dry, or just damp and muddy.
I have had no luck with optical grade Cerium Oxide in a tumbler. The only times I have had some luck was with the beryls and no additives. If the other polishes do not work, Cerium has saved my day. I spit on a felt buff and use my handpiece to polish watch crystals if the scratch is not too bad. Cerium is great for that.
With tumbling, let it soak, get real muddy, add stones, and tumble shaking the bbls end for end and let it rip. Caustic soda is a no-no with some things. If you need to add something, try Borax.

[spacegold]

I'm with Doc. You are getting an organic polymerization reaction of some sort, and the only organic material is the soap. Try it without, or with borax.

[connrock]

Tom,
Optical Grade cerium oxide is white.

The pinkish colored material is called Polish Grade and is much less expensive.

Here's a helpful link that will give you a few ideas:

www.micronmetals.com/cerium_oxide.htm

As for your gummed up problem I have to go with Doc and space!!

Get rid of that lye soap and use Borax.

connrock

[Sabre52]

Hmmm. I do mainly all quartz gems like agate and jasper. I used the sort of flesh colored cerium for quite awhile with good results but when I switched to Rockshed aluminum oxide the results got even better. I use borax and Ivory Snow for my cleanup and burnish. I suspect your soap additive may be the problem too. as the cerium was always pretty good as a polish. Oh, and you've got to watch quantities on both polish and prepolish too. I recently changed tripoli brands and had to way cut the amounts I was using per barrel as I was having the loads gum up too...mel

[181lizard]

Howdy Tom...I'm Liz & we're from the same neighborhood!

Been comin here long?

Stick with us kid...you've just found a great website!

[wes]

I am new to rock tumbling. Using Cerium Ox to polish. Not shining the rocks. But...I put in plastic pellets, rocks , 2 tablespoons of CO and filled with water up to rock level like I did in 1st 3 stages. Was this incorrect? Did I use too much water? What is the proper formula for polishing step with CO? I'm using Nat'l Geo hobby rotary tumbler. Thank you.

[NRG]

You might do better making your own thread rather than resurrect a 14 year old one


Welcome to the group!!

[Fossilman]

Oct 22, 2006 19:03:27 GMT -5 Sabre52 said:

Hmmm. I do mainly all quartz gems like agate and jasper. I used the sort of flesh colored cerium for quite awhile with good results but when I switched to Rockshed aluminum oxide the results got even better. I use borax and Ivory Snow for my cleanup and burnish. I suspect your soap additive may be the problem too. as the cerium was always pretty good as a polish. Oh, and you've got to watch quantities on both polish and prepolish too. I recently changed tripoli brands and had to way cut the amounts I was using per barrel as I was having the loads gum up too...mel

Can't beat therockshed for high quality grits and polish powders... Shawn knows his stuff..