(This is the 11th Post in this series – the first Post can be found here.)
Steve Hart, in “Modern Rock Tumbling” (2008), attests that burnishing can make a “significant difference” in the appearance of polished stones (page 44). As one tumble-polisher has put it, “Sometimes stones are a little ‘hazy’ when they come out of the polish and small particles of polish are hidden in the tiny crevices of the stones. It helps to clean them up by burnishing the rocks in soapy water for 4-5 days.”
It was while I was doing my initial internet searches on how people tumble polished stones that I came across the idea of a post-polish burnishing tumble for up to a week using borax. Borax is sold as a white powder that dissolves easily in water. It has been used as a detergent, a food preservative (now banned for this use in some countries), an anti-fungal compound, a weed killer and a low-toxicity insecticide. It is used by tumble-polishers because it is a clean soap, lacking perfume and other additives (some use Sunlight or Ivory soap flakes instead). So I tried it and I thought that the results were great – polished stones seem to sparkle just a little more. Whether this is the case or not, I am not entirely sure, but I have the attitude that if it seems to work, why not continue it! In general, I think that a soap tumble of newly-polished stones for a day is the least that should be done, to remove polish particles and to give a final clean. My established routine practice is a tumble for around one week in one to two tablespoons of borax. [NOTE: April 2021 – I now do a borax tumble for an average of two days and the results still seem to be good.]
I polished the 40 Riverton stones, that this series is about, in borax for 10 days straight after the pro-polish tumble. This was a little longer than usual as I was busy with other things over this period. Firstly, the washed stones and pro-polish beads were replaced in the 4lb barrel, with water, and then about two tablespoons of borax were added.
At the end of the tumble, the stones were washed then given a final weighing:
The starting weight of the unpolished stones, right before I began to work with them, was 1605 grams, the end weight is 1244 grams. This means that 361 grams were worn away during the whole polishing process, which is 22.5%, just over one-fifth, of the stone material.
SUMMARY OF TUMBLING STAGES AND TIMES (as taken from Tumbling Log)
(Stage 1 = Stone collection)
Stage 2, 100 grit = 9 days 10 1/2 hours, followed by soap tumble of 12 hours
Stage 3, 220 grit = 9 days 2 hours, followed by soap tumble of 18 hours
Stage 4, 320 grit = 9 days 19 1/2 hours, followed by soap tumble of 3 days 1 1/2 hours
Stage 5, Pre-polish = 5 days 19 hours, followed by soap tumble of 20 hours
Stage 6, Pro-polish = 14 days 5 hours
Stage 7, Borax = 10 days 2 hours
This adds up to the stones spending 49 days and 8 hours tumbling in grit and polish, with an additional 15 days and 5 1/2 hours spent tumbling in soap and borax (a total of 64 days and 13 1/2 hours). Note that this is not the minimum time needed – I often extended tumbling by a day or two in some Stages, and there were occasions where tumbling in soap went on far longer than usual. Furthermore, a smooth beach stone can usually skip Stages One and Two.
NOTE: March 2021. Due to my supplier now stocking only one grade of tin oxide polish powder instead of two, only six stages need to be followed. Details on this can be found in UP-DATE OF “The Seven Stages in Tumble Polishing Stones” – One Less Stage.
The following Posts in this series look at each of the polished stones in detail to assess the impact of this process on them. The first examines Stones 1 to 5.
At the end of your stages you listed , you said 15 days and 5 and a half hours in soap and borax. What kind of soap did you use ? Or was it only borax that you used ?
Hi Teresa, good to hear from you! Buried in an earlier Post in this Series https://tumblestoneblog.wordpress.com/2017/11/27/the-seven-stages-in-tumble-polishing-stones-stage-two-100-grit-tumble-15-25-november-2017/ are the comments: “I have seen various sources recommend the use of a mild low-sudsing soap, with Sunlight mentioned. I have managed to track down an outlet for Sunlight soap and I grate the cakes.” So I use borax only for the final burnishing stage, and Sunlight soap for the shorter cleaning tumbles after the previous stages. Other people use soap like Ivory flakes etc. – the less perfume and additives, the better (reduces the chemical processes that might take place in the barrel).
Can you please tell me how much of the plastic beads you use in the polishing process? Do you use them in each stage or just in the final stages. Are there any other types of beads, small round stones, or other materials I can use in the tumbler? I have been using the beads but they are super tiny and I seem to go through quite a lot of them each time. I do keep some from each stage and store accordingly to re use, which cuts down cost quite a bit. I also have been using little pieces of foam box as a buffer, which seems quite good but the supply now limited. Any suggestions would be greatly appreciated. Alexandrah.
Thanks for your inquiry. I use plastic beads at all stages, though not many for coarse grit tumbles and more for the polishing stage. For a 3lb barrel, I use 1 or 2 tablespoons for coarse grit, 3 tablespoons for fine grit, and 3 or 4 tablespoons for polish. For a 4lb barrel, maybe add another 50%. I probably use a bit more than other people do. I store the used beads, separate containers for each stage, and re-use them many many times. I am meticulous about not losing any of them, as I don’t like plastic in the environment. I may move to using something else sometime. I have tried ceramic media as an alternative but have been unsure about how successful they are – I know a number of people use them regularly and very successfully. I have no experience with other material. Sorry I can’t be more helpful.
Can I take using beads literally? I’m thinking as in plastic beads with a hole for stringing.
The plastic beads usually used by tumble polishers are quite small. The beads used in necklaces would likely be about 10 times the size – this will reduce some of their efficiency in cushioning stones and in carrying grit etc to the stones. It will also depend on how soft the beads are, how quickly they wear, especially in grit tumbles. However, probably no harm in trying them, that’s the only way to find out.
Thank you. It’s been 50 years since I’ve tumbled rocks. I honestly don’t remember using any kind of media.
Hi Julie. Plastic beads have been used for a while as a standard input to modern tumbling. However, there are alternatives and I am currently thinking about experimenting with replacing them with very small stones. Still thinking about it. See this Post for some of my thoughts and research https://tumblestoneblog.wordpress.com/2022/09/05/alternatives-to-plastic-pellets-as-tumbling-media-reviewing-the-advice-part-one/