Tumbling Polymer Clay Beads January 13, 2010

Posted by Allcrystal in 1.
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My jewelry website: Infinite Spirit

Please understand that I am new to using polymer clay and do not claim to know anything about this product yet. My only interest in clay at the moment is making beads from flower petals. I do not want to use an artificial finish on my beads and want to retain a handmade quality to them. Once I started learning a bit about making clay beads, I cringed at the thought of sanding and polishing 8-16mm beads by hand so I started doing some research on using a rotary tumbler. I already had a Lortone rotary tumbler that I used for tumbling stones a few years ago and thought this would be a way to put it to good use again.

In my research, I read the many warnings about using tumbling grit with polymer clay in a tumbler, but no one ever said what kind of grit they tried. I just happened to have 5# of Cerium Oxide (CeO) in the basement (which is a lifetime supply), so I thought I’d give it a try; CeO is normally used for a final polish with stones, and is dark cream in color but I’ve also seen that it comes in white. It is available anywhere they sell grit for tumbling stones, and on eBay. The price varies between $4 and $8 per pound.

• Cerium Oxide is rated as 6 on the mohs scale (mineral hardness)
• Fingernails are rated as 2.5 mohs and can easily scratch polymer clay; therefore polymer clay is softer than 2.5 mohs
  
• Cerium Oxide has a grit of between 1000 and 1200
• Typical Cerium Oxide particles are about 3 microns
• Thin mixes of Cerium Oxide are known to work best for most applications
• Cerium Oxide is used typically to polish glass and as a final polishing tumble for stones
  

And so we have . . .

The Great Bead Tumbling Experiment

The Second Experiment:

I have simplified the tumbling process since the first experiment (at bottom of page).

What I used:

• Lortone tumbler – any brand will work
• Cerium Oxide
• Water
  

What I did:

I made 21, 16mm polymer clay beads with a bead roller. I used a bead roller so I could start with relatively smooth beads. I blended various colors of Fimo translucent clays and added different powdered flower petals to each bead. I used these ingredients because that’s what I will use most frequently but any brand of clay should work with or without additives. I baked my beads per package directions.

I filled my tumbler barrel (which is black rubber) half full of tap water and stirred in 4 Tablespoons of Cerium Oxide (CeO); this made a thin, watery mixture. I started with 2 Tablespoons of CeO, but after 4 hours of tumbling I decided that the progress seemed a bit slow so I added 2 more Tablespoons full. Use your own judgment as to how much you add, but I wouldn’t use more than 4 Tablespoons because you will most likely be wasting CeO.

I then placed my beads in the barrel with the mixture and tightened down the lid. If you have a lot of beads, then you may need to add more water – your barrel should be 1/2 to 3/4 full no matter how few or how many beads you have. This is so you get a good tumbling action within the barrel.

I tumbled the beads for a total of 12 hours, checking their progress every 2 to 4 hours. After 6 hours, there was a marked improvement to their finish but I tumbled for a full 12 hours anyway just to see what would happen. Use your own judgment with your tumbling time – there aren’t any hard and fast rules here. This is a quiet tumble – just the gentle hum of the motor and beads rolling around in water inside the barrel.

I tumbled all of the different beads together – from deep red Poppy to white Jasmin and got no color bleeding and no transference from the rubber barrel.

After tumbling, I rinsed the beads with running water and dried them with a towel to remove any CeO residue. The pictures here are in natural sunlight, in front of a window; there are no photo enhancements. The “trashy” specs in the beads are the powdered flower petals. These beads have not been sanded, buffed, glazed or polished in any way except in the tumbler as described above.

Buffing after Tumbling:

Here are the same beads after being buffed with a bench buffer with artificial light using a table lamp; nothing fancy. Not bad – and quite an improvement! Remember, the “trashy” specs are flower petals. The second picture is of the same beads in natural light. This will serve my purpose because I want to maintain a handmade quality.

There are lots of different kinds of final polishes available for tumblers and stones, so it would be interesting to try something different and compare results because there might be something better.

I am not saying that this the best way to finish beads, but I am saying that is one way to get results. Your results may vary and I would like to see what you do with this process so we can perfect it.

Important Notes:

• I have retained the Cerium Oxide and water mixture for future tumbles because there is so little abrasive action involved with polymer clay. Since the mixture is not a heavy slurry, it only acts a light wash as it swirls around the beads gently polishing them to a nice shine. I’ll keep using it over and over until it no longer gives the desired results. At this point, I have used it three times with no lessening of its polishing capabilities.
• Even though this CeO mixture is thin, it is recommended that you discard your tumbling mixture outside on the ground instead down the drain as to not risk a build up in your plumbing and possibly cause a blockage. Simply rinsing your clay in the sink with running water should not put your plumbing at risk. If you are concerned though, you could wipe the beads off with a paper towel before you rinse them.
• Never use any kind of soap in your tumbling barrel except Ivory soap. I don’t think this type of cleaning is necessary with clay but if you want to try it, it shouldn’t harm anything. Ivory is the only soap that is pure soap (which BTW, is why is why Ivory floats) and is the only soap that is recommended to use in a tumbler. Other soaps contain additives and detergents that can harm the tumbler’s rubber gasket and barrel, and leave an unwanted residue. If you feel like you need to use the soap process and you can’t find Ivory laundry flakes (which is best), you can put a few shavings of Ivory bar soap in clean water with your beads and tumble for an hour.
  

Now I need to work on making something pretty instead of experimenting.

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The First Experiment:

I think I’ve done as much as I can with this experiment. The results are pictured here and I have mixed feelings about how things turned out; I’ll do things a bit differently next time. It may just be that these beads are kind of ugly and that is tainting my opinion of the process.

The process was easy and cheap, and even though these beads aren’t very pretty, they do have a decent shine. The color is a bit goofy, but they were colored from the Hibiscus petals so I had no choice in the matter.

There are some visible white specks now and I can’t tell if it’s from the texture of the flower petals or the Cerium Oxide trapped in pits and crevasses. I got some color bleeding in the water during the tumbling process due to the flower petals – the clay is translucent white and nothing was added other than the flower petals.

I tried a dry tumble with oatmeal and dry CeO for a few hours and that may be where I messed up and got the white specks, so don’t try that if you read about it on a tumbling site like I did – it did get caught in the holes. I couldn’t see that it did anything positive and possibly added the white specks.

My final 2 hour tumble was with water and Ivory soap scrapings to give everything a good cleaning. No, you may not use another brand of soap, liquid or otherwise. Ivory is the only soap you can use because it is pure soap, without any additives or detergents. Other soaps will eventually ruin the rubber barrel and its seals. This step may not have been necessary if I had not done the dry tumble.

I have not done any sanding or buffing other than wipe the beads off by hand with a terry cloth towel to dry them and remove any remaining CeO residue after tumbling. OK, maybe a quick hand buff with the towel was also done, but nothing more.

I don’t know if this is a good process or not, so you tell me what you think. I will try the river rock method at a later time and compare the results. If you’ve already used the river rocks, I’d like to hear your opinion as you sit there and view these results.

Next time I will not: use any kind of tumbled stones as filler or use the dry tumble method with CeO and dry oatmeal.

This 16mm bead was made with Fimo translucent clay and has a lot of powered Hibiscus petals added which is why there are all those tiny specks. The overall size of the bead was maintained in the tumbling process. This is a work in progress. No buffing has been done to the bead pictured other than a gentle rub with a terry cloth towel to remove the CeO residue after drying.

The same bead held out the window in direct sunlight. You can see how much shine there is at the bottom of the bead where the rod is reflected. All of the large white areas are light reflections. The tiny white flecks are sparkles in the powdered petals.