Rock Tumbling Secrets

Rock Tumbling Secrets

Want to get some more great info on tumbling rocks? Check out our kit,  How to Polish Your Own Stones.”

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Rock Tumbling Secrets

There is a beach out on Whidbey Island (that’s in Puget Sound here in Washington state) that we love to take groups to in order to find the best assortment of stones and rocks for their collections or to study. We can find agates, lavas, serpentinite, quartzite, jasper, and so many others. The ocean has tumbled the rocks on the island. These rocks are so shiny and smooth, at least, while they are still wet.


But as soon as they dry off, they are dull, not even beginning to exhibit the brilliance of when they were wet. This is so often a disappointment to the kids, as they pick their samples with such care as to color, shape or size. But especially color.

Here’s a quick solution! Give the rocks a good coat of shellac or polyurethane that makes them appear to be polished. But the more permanent solution is to tumble them yourself to get that glorious shine!

Rock tumbling can be a very fun hobby. In fact, many folks have tried it, and almost as many have quit. It takes time, and many kids don’t want to wait 5-8 weeks for results! And there are tricks to getting it right, and often the instructions that come with your tumbler aren’t very clear about that. So with that in mind, and if you are one of those that wants to tumble rocks, here are some pointers for you!

Get a good rock tumbler!

First, and most importantly, don’t spend your money on a tumbler from a craft store, or even one of those that you can find in a museum. These are noisy, and often made of very inferior material that breaks easily. They may be good for one or two batches of rock tumbling, and then you are out of luck. A rubber barrel would be something good to look for.  The noise that is generated will be significantly less.  And be sure to get a tumbler from a reputable maker. We suggest Lortone, among others. 

Where to put the tumbler?

We would suggest that you put the tumbler somewhere that won’t drive you to distraction. If you followed our advice and got a tumbler with a rubber barrel, then it may actually produce a rather soothing white noise. But soothing or not, we keep ours in the garage. You should also consider if it is convenient for you to get to in order to tend to it. It should not be out of sight, out of mind. That could be a mini catastrophe waiting to happen!

How do I choose rocks to tumble?

You need to choose rocks that are the same hardness for each batch that you do. If you are not familiar with this idea, be sure to look up what is the relative hardness of the stones you are tumbling. And be aware that some stones, like obsidian, are just too soft to tumble. Because you will have nothing left if you tumble them.

Also, mix the different sizes of stone. Small, medium and large. And mix jagged with smooth. You want to fill your tumbler about ¾  full. When you finish the whole process, a good deal of the stones will have been ground away, leaving the barrel only about half full. This is normal.

Can you identify those rocks?

Some of the fun in tumbling stones involves knowing rock types. You can learn how to identify rocks with our Rock Identification Made Easy Kit!

 BUY NOW! Rock Identification Made Easy Kit!

The First Step in Rock Tumbling

After you have selected your stones to polish, put them in the barrel, and fill the barrel with water to the top of the stones, and add the grit. After putting the stones in the tumbler, along with the appropriate grit, then you wait. I would suggest 10 days for each stage. Then you will clean out the grit at the end of each stage, and then put in a smaller grit and repeat the process. You will do this several times before you get to the finished product. And always be sure to clean out the barrel and the stones completely after each stage. You will go through three stages of tumbling, with three different grits,  before you get to the polish stage.

Cleaning the grit out after each step is important!

First, don’t run the grit down your sink. That could be a costly plumbing bill, as the grit could harden in your pipes. Find a good place outside to rinse the grit, using a garden hose. And be sure to be very thorough. Any leftover grit in your stones will etch them as they go through the next phase. Your barrel, as well as the stones, need to be completely free of any residual grit. Use something like Tide powdered detergent to clean the tumbler after each step. Do not use a liquid detergent! It may leave residue that will etch your stones.

The Pre-Polish Stage

Now, before proceeding onto the polish stage, examine the stones for the “smoothness” factor. If you are satisfied with the smoothness of the stones (they should feel satiny, but have a dull finish), then place the stones into the barrel and again fill with water to the bottom of the top layer of stones. If, however, you are not satisfied with the smoothness of the stones, replace the stones and repeat this most recent (pre-polish) stage. This stage is crucial, as it sets up the stones for an effective polish. Add the appropriate pre-polish grit and tumble again continuously for 10 DAYS. If you are satisfied, go on to the next step. Be sure to remove any broken stones. Carrying them forward will scratch the other stones. They can be tumbled again in the next batch of stones.

The Polish Stage

Now, here is what you have been waiting for, the stage when you put a shine on the stones. After cleaning the barrel and stones thoroughly, place the stones back into the barrel, fill with water to the bottom of the top layer of the stones and add the appropriate amount of polishing grit. At this stage, the barrel usually has a lot of room left in it. So what now? Use some kind of media like small wooden pellets or plastic beads to fill some of the space.

Just a reminder. Above all, do not use pellets that have been used in a stage where you were using grit. Only use new pellets or clean pellets. The media will help carry the polish and also assure that your stones will not be scratched or damaged during the polish stage. If you only use this media for the polish stage, there is no need to clean it between batches. If you need media for your previous stages, use new or different media.

Tumble the stones on the polish stage for 10 days. At the end of this stage, take out a few of the stones, rinse them and check the shine. If you are satisfied with the shine, then you are ready for the burnishing stage. If you are not satisfied with the shine or the stones are dull in appearance, you will have to go back to the pre-polishing stage and repeat that stage. More polish will not help! More time will not help!  You must repeat the pre-polishing stage. Be sure to clean your barrel thoroughly using something like Tide powder, as a dirty barrel may have contributed to the problem.

The Burnishing Stage

When beginning this stage, it is not necessary to clean the barrel or stones. Simply dump as much of the polish liquid as possible (not down your sink!), and then add water up to the bottom of the top layer of stones. Next, clean the lid and seal of the barrel so that there will be no leakage, and dry thoroughly. Before replacing the lid, add one cup of plain Tide powder detergent. Do not use a liquid detergent, as this will ruin your polished stones. Liquid detergent will scratch the newly polished stones! Reseal the barrel and let tumble for a day or so. Burnishing helps clean the stones and puts that extra shine on them. Remove the stones and enjoy what you have waited so long to appreciate! Then do it again.

And now you have it! Rock tumbling made easy! If you have specific questions, don’t hesitate to contact us for some sage advice!

Watch a short video from Rockman Pat about rock tumbling.


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51 thoughts on “Rock Tumbling Secrets

  1. Great advice. American Geode has been tumbling rocks since we got to North Georgia in August, in a cabin in the woods, with a creek nearby. We are lucky to have a lifetime supply of stones.

    We have a 20lb tumbler that allows us to tumble larger stones.

    Good luck everyone. Rock tumbling is the perfect hobby to complement rockhounding when you have rocks not quite pretty enough for display on their own, but you do not want to get rid of them either.

    We are posting before and after videos on our blog.

    Good luck!

    1. Dedicated to the one rock hound

  2. We are wondering about dry tumbling vs wet tumbling. Can you explain the differences, advantages,disadvantages? Thanks

    1. HI Ted, That is a great question. We do not dry tumble. Dry tumbling is just that – tumbling without water in the tumbler. The idea is that by starting with a larger grit that it breaks down and thus serves as the next stage in the tumbling, without having to go through the mess of removing the old grit, and putting in new, finer grit. It is supposed to cut down on the time needed for tumbling, but the reviews on it are very mixed. The general consensus is that it doesn’t greatly improve the process, if at all, and that it is noisier. Does that help?

  3. Can you explain why you have to redo the pre polish stage before polishing again if your stones are not super shiny after polish?

    1. Thanks for your question. Just putting the stones through the polish stage will not help. You have to return to the pre-polish stage. Continuing to polish the stones will not take care of the problem, which is that they weren’t sufficiently smoothed in the pre-polish stage.

    2. Polishing more will not help. The stones have a refining flaw that cannot be corrected by polishing more. The prepolish stage should take care of the flaw and finish the job to get them ready for polishing.

  4. My daughter lives in Oak Harbor on Whidbey Island. Where is this beach? I would love for her and the grandkids to go gather stones. We are in Iowa and it would be fun to polish what they gather and send them back to the girls.

    1. Thanks for the question, Eileen. The beach is in the area of Ebey’s Landing and the Port Townsend/Keystone Ferry. If you are coming from Oak Harbor, take highway 20 towards the Port Townsend/Keystone Ferry. In Coupeville, turn right on S. Main St. It becomes Engle Rd. Follow Engle Rd. past the ferry terminal. At this point, the road becomes Highway 20 again. For about a mile or so after the ferry terminal, you will be driving through the Ebey’s Landing National Historic Reserve. At the end of the reserve is a “T.” If you turn left, you stay on highway 20. You want to turn right here, on Keystone Ave. I don’t know if there is a sign for it, though. It is a small side road. When you turn, the beach will be directly in front of you. You probably will notice that the beach for the reserve is immediately adjacent to the beach where we forage for the rocks. DO NOT PICK UP ROCKS IN THE RESERVE! It is against the law, even though it is the same beach! The beach that I directed you to is smaller than what is designated as the reserve, but still plenty to gather there! On the beach I directed you to there is a marker (unless it has been removed) showing where the boundary begins for the reserve, so you know not to collect there. There is a small parking lot, and a few homes along this beach. Also lots of driftwood. On a practical note, sometimes there is a portable outhouse there, and sometimes not. So be prepared! The closest bathroom is at the ferry terminal. I hope that helps.

  5. This is such great info! Thank you! I live down in Olympia, so not far 🙂

    When using smooth rocks you find at a river or on the beach, like you described, do you have to do this entire process or can you just start at the polishing stage since they’re already very smooth?

    Also, does it have to be Tide for burnishing? I use Biokleen laundry powder to be eco friendly and would prefer not to buy Tide.

    Thanks! 🙂

    1. Thanks for your question. As far as polishing, you can skip stage 1, but do start with stage 2. Going straight to polishing would not give you the results that you want. As far as Tide, it was what was recommended to me, and has given me superior results. You should certainly try Biokleen. Just so long as it is not liquid (you said it was powder), and no perfumes. I hope that helps.

  6. Very cool intro to tumbling. It’s a great hobby as well as a lesson on natural weathering. As a teacher, I’ve tumbled in class, taking photos of the rocks after each stage of tumbling.
    I like to rockhound on beaches in Oregon during the summer. The agates and jaspers tumble nicely. While at home, I collect Crowley’s Ridge agates. They are a good tumble too but require more “finesse “.

    1. So many of the beaches here on the west coast are great resources for finding specimens. Love the Crowley Ridge agates!

  7. Hi
    This is my first foray into rock tumbling . I have gotten to the final stage all the rocks are smooth as silk but not shiny like they are wet. I added some cork and a bit of hard soap but not sure if it was enough . Please help! Should I have emptied the stones out and cleaned the tumbler of the polish?

    1. Hi Renee, this has happened to me before, too. Not knowing what might have led up to this problem for you, I can only guess. But my first and best suggestion would be to go back to the pre-polish stage. Be sure that you do completely clean out the barrel after each step (but not in your kitchen sink!). More polish will not help, and a dirty barrel will certainly keep you from getting the shine that you want. Let us know what happens!

  8. I just started polishing. I had a faculty member retire and leave me his industrial tumbler he used for soil analysis. I have a nice secluded/private pebble beach on our family property on Lopez Island so I grabbed a bunch of those and gave it a shot. I did not do near 10days on each sized grit. Maybe a day it did work for the softer stones. I really don’t want the super polished look I want them to look natural with some smoothing but not have look so dull when dry. I am a research scientist of 35 years so I thought I would try something. I ended up getting them soaking wet in beez wax furniture polish and let them sit for about 30 minutes I then hand buffed with a fine waxing towel the excess. The result turned out pretty good so far I can see the stratification detailed of the stones while keeping somewhat of a natural look! Darn scientists always messing with stuff LOL!

    1. Well, that is certainly creative, Collin! It sounds like you worked out the perfect solution to your problem. I don’t think I would have thought to try furniture polish!

    2. I have used mineral oil to get that satin finish. It worked well for me.

  9. Hi all ! I live in the Puget Sound Region and have found wonderful agates in Ocean Shores just to the east of the jetty. You go along the jetty close to the little Museum and old casino area. There is an entrance to the beach near there that is blocked by a cable. You step around the cable (which is permitted), walk to the beach (about 1/4 mile or less) and head to the right (west?). Look on the upper part of the beach for agates. Go there after a storm before anyone gets there for the best finds. There is also lots of wildlife there — eagles, sea lions, deer, and even the occasional black bear. It’s a fabulous natural place near to civilization!

    Just FYI…I am a jeweler and have polished many types of gemstones with cerium oxide on a soft, high-speed wheel to get that final shiny finish. I’ve used both a buffer setup and a dremel wheel–both work and don’t require days of waiting like a tumbler would. You can try other substances — fine diamond grit, toothpaste, etc., just don’t use multiple substances on the same wheel. This will contaminate the process. I’m still experimenting with various types of wheels and will keep you posted.

    Also, if you love minerals I’d suggest you visit Jerry’s up in Kent. Fabulous rock shop !!!
    Take care you all.

    1. Thanks, Tony, for the information. We will have to go there! It sounds great! I have also used cerium oxide and it gives great results. Thanks for sharing that tip.

  10. Is it possible to use some already polished rocks as a filler in the final polish stage of another batch? The rocks are of the same approximate hardness. Thanks in advance for any thoughts!

    1. Dave, no, you need to go back to the pre-polish stage with the polished agates that you are going to use as a filler. The stones need to be of a similar finish in order to polish well. So you need to go back to this stage. But rather than do that, you could use wood dowl rod pieces 3/4″ long, as filler. I do that all the time.

  11. I collected some agates and am very excited to tumble them, but there aren’t very many and certainly not enough to even fill the tumbler 1/4 of the way. Can I still tumble a small quantity of rocks?

    1. Hi Karen,

      You would need to put some media in with it, like wood pieces (like wood dowels that are about 3/4″ long) to help fill it up. Otherwise, they will bang too much against each other.

      1. I have used rubber bands with great results! They are a good filler and help with finial polishing.

        1. I have never tried that. Thanks for the info!

  12. first of all, I want to thank you for all of your help with everyone, so nice of you.
    I have a question, I have three months polishing pebbles and I am using a plastic cylinder (rotary).
    The whole process is done dry I just add enough water to keep it moister. When the whole process of the media is completed. I then go to the polish step and for this, I use a corncob mixed in with the polish powder. I mix it with the pebbles and let them run for three days. when is time to get them out I notice the media is stuck on the pores of the stones. what is weird about it is that not on all the stones it does that.
    can you please help me and let me know what I am doing wrong?
    thank you so much.

    1. Good morning! I will try to answer your question. When you put the corncob in, are you saying that pieces of the corncob stick to the pores? Or does the polish stick? If it is polish, then it usually can be removed easily with a toothbrush under running water. Please feel free to share more info if I am not understanding.

  13. Hi, I’m brand new to rock tumbling and even rock/ gem hunting ! My question is I have noticed how expensive the grit powder is and was jwondering if it’s reusable at all (at least the first and second grit stage, thanks!

    1. Yes, grit does get expensive! I have never reused the grit from the 1st or 2nd stages. I know that some have reused the grit from stage 1 fo stage 2, but never more than once. Like I said, I have never done this. It just creates such a slurry of a mess.

  14. Hi, I have been tumbling for a little over a year now and I have accumulated quite a bit of gear in that time period. From tumblers to saws to wheel grinders and more. My issues seem to always be in the last two stages of the tumbling process. I have a few questions for you please. First, if you don’t tumble stones without cracks, put, or blemishes there is not much left to tumble. So in-between stages can you grind or cut out bad spots? Would you make batches of stones w/ similar blemishes ie:cracked, pitted, jagged, or smooth…? Same moh ofcourse. Last question is- what do you think about getting separate barrels for the last two stages? One for pre-polish & polish or just polish? I find the cleaning of the in-between stages very tedious and time consuming. I am quite a**l yet have had too many batches spoiled by grit straglers. Lastly
    any advise on said in-between stages? I have quite a bit invested in this so I am willing, much to my beautiful loving wifes dismay, to spend a little more for time saving & quality results. Sorry for the book but please help. ? Thank you so much for your time. I live in Idaho btw???

    1. In all my years of tumbling, I rarely removed many stones in the last two states of tumbling, Anything with pits, I just washed a little more thoroughly. Your comments reinforce what I always tell parents before purchasing a tumbler – “…the most frustrating hobby you can do to a kid!” The last two stages are the most frustrating. To help here, sometimes I have gone longer in the 1st stage especially if the stones were very rough and hard at the beginning. And I always mixed the sizes of stones, never the same sizes of stones.

      I never used separate barrels, although I know of many people who did and if you have the money, it is not a bad idea. However, you will still need to keep the lid and recess clean to prevent leaking in future batches.

      You will always lose anywhere from 15-20% of your stone volume in the process, simply because of the tumbling process. Do you use any kind of media such as plastic pellets or wood pellets to fill up the space in the last two stages? This helps. Right before the prepolish stage after washing out my barrel and before putting the stones back into the barrel, I do sort them, but not for breaks or flaws. I can pretty much tell how a stone is going to do and if a stone does not look like it will polish very well, I go ahead and remove it for the beginning of a second batch. Using a toothbrush to clean your stones before the prepolish stage is a help.

      Knowing that I will lose quite a bit of volume in the process, I tend to overfill at the beginning and just run longer, as much as 5 days longer in the first stage. It took me a few years to figure out a routine that seemed to work in my rock tumbling. Also, be sure you are tumbling stones of the same hardness! That can contribute to your problem. Actually, I only tumble LIKE STONES together. Doing all jasper together, all agate together and all petrified wood together seems to have helped.

      1. Thank you for the advice. I do use ceramic and plastic media of various sizes for most phases. I try to run similar stones together but so far I have not bought much to run batches that are the same. I have many piles at different stages and different types. I will be more patient and wait til I get enough of the same for a batch. I run two three pound barrels and two six pound barrels and have a twelve pounder as well. Sound advice about going with Lortone. I love my qt66. My first was a Chicago Electric…I have rebuilt it to many times to count. It now has a Lortone motor and i replaced the shafts, put on a metal pulley, and real berings, and quit buying belts from China. Almost runs to fast now but I haven’t had to work on it for a couple of months now. My newest project is converting a five pound dry vibratory tumbler for parts to a wet one for stones. On round three but I think(hope) I got it. Thank you again for the advice.

        1. You are quite welcome. I hope your projects go well!

  15. Hi, I just had a question about the burnishing stage? You mention to use 1 cup of Tide powder, but if I have a smaller 1 or 2lb machine how much should I use? Will using too much effect the results? Thanks!

    1. You are right, the 1 cup of Tide is what we use for a 6-pound tumbler. For smaller tumblers, use less. But whether you use too much or too little, it won’t hurt the stones. Just a reminder not to use liquid detergent! It will etch the stones!

  16. Hi there, I have enjoyed reading all the questions and responses! My questions is about the final polish stage in the tumbler. I have very little volume left of the rocks, what do I use to fill up the space? I have do have some small and large ceramics. Can I use those in with my nice smooth rocks and the aluminum oxide polish? Will the ceramics ruin the polishing stage?

    1. HI Jeff, thanks for the question. Many people do use ceramic pellets. Over time, they will begin to degrade. I would not recommend using ceramics of any kind that were not designed for this purpose. I like to use wood pellets. For this, you could simply get a dowel rod from the hardware store, and cut it into sections. This has worked very well for me.

  17. Hi all 🙂 so glad I stumbled onto this “blog”? Lol I have been a lifelong rock hound and recently(the last year and a half) started tumbling and have found that in between stages adding my load back into the barrel and just using a drop( literally just one) of dawn dish soap and letting it run anywhere from 5 hours to a day is usually my window of tumbling then rinse them it gets all the grit you didn’t know was hiding still in the rocks. Also during the burnishing stage I’ve used borax or ivory bar soap shredding and both work wonderful for me(I’ve never used tide haha). Thank you for giving us a space to bounce ideas off each other and your information is spot on !! I live in Elma area so I’ll have to make a trip up to Whidbey as it sounds amazing!!! If you get down this way the chehalis river has some amazing agates, jaspers, and pet wood!!! Thanks again and hope everyone is staying safe and healthy !!

    1. Those are really good ideas! They take a lot of the work out of trying to clean all the grit out of troublesome areas. And thanks for the info on the Chehalis River!

  18. […] The quickest solution to this is to give them a good coat of shellac or polyurethane that makes them appear to be polished. The more permanent solution is to tumble them yourself to get that glorious shine! Rock tumbling can be a very fun hobby. via […]

  19. Thank you for such useful information! I just got back into rock tumbling with my daughter and am learning so much, but find navigating the web for consistent information (where it seems everyone just wants to sell you stuff) is a headache. It’s so refreshing to see these Q&As with tried and true suggestions. I just finished my first batch (had to rerun prepolish and polish stages) on a purchased bag of mixed variety – jasper, rose quartz, and some other rocks. Most turned out great (still have to burnish) but some of the rocks aren’t as shiny. I’m guessing it’s due to slightly softer rocks and will try to stick to tumbling the same type of rock at a time. I’m so glad I stumbled on this forum. I also live in WA but on the east side of the state. 🙂 Thank you!!

    1. Thanks, Deana, for your kind thoughts. Yes, this blog has become quite the sharing place! We have picked up some very good ideas from many who have shared their expertise.

  20. So I have the rocks in the Tumblr 2/3 full. I have the grit in there. How much ceramic medium should I use ,? Do I need to fill it to the top ?

    1. You don’t want to underfill it, giving the stones too much room to bang around, which can cause them to chip and break. 2/3 full is probably too empty. But you do not need to fill it to the top. Filling it to the top will not allow them to tumble as they should. So it really is by guess and by golly. I’m sorry I can’t be more precise.

  21. If the grits are made of steel and therefore should not wear out or break down completely after only one use, why shouldn’t I be able to save back and re-use each grit-and water slurry in successive stages of tumbling each new batch of rocks?

    1. The grit is silicon carbide (it is not steel), and it does break down after tumbling. Many people have tried to use it in successive stages without success.

    2. The slurry consists of worn-out silicon carbide, and the residue from the rocks (the part that has been worn off of the rocks.) So it is hard to be able to predict just what is in the slurry, besides broken down rock particles and broken down silicon carbide.

    1. Certainly, you can! Rock polishing is a very popular hobby.

  22. […] The quickest solution to this is to give them a good coat of shellac or polyurethane that makes them appear to be polished. The more permanent solution is to tumble them yourself to get that glorious shine! Rock tumbling can be a very fun hobby. via […]

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