Clay - Tumbling Speed Additive

If you are tumbling with the Thumler's Model MP-1 tumbler (which has a two-pound capacity barrel), you can follow the instructions below, but use about two level tablespoons of grit or polish in each of the tumbling steps (Step 1 through Step 4).

When tumbling you will place enough rocks in the barrel to make it about 2/3 full. Then, add about two level tablespoons of grit for each pound of rock. Finally, add enough water to almost cover the rock. Now seal the barrel and place it on the tumbler.

STEP 1 - Coarse Grind

The first step of the four-step tumbling process is to run the rocks in the tumbler with coarse grit. You begin with a barrel that is about 2/3 full of tumbling rough, then add two level tablespoons of coarse grit (we use 60/90 grit silicon carbide) for each pound of rock. Then, add water until the water line is just below the top of the rocks. Seal the barrel and run for about seven days.

At the end of seven days, open the barrel. You will find a barrel of rocks in very muddy water! Dump the contents into a screen or a colander over a plastic bucket and rinse off every speck of grit and mud. Wear safety glasses to protect your eyes from a splash of mud.

DO NOT ALLOW THE GRIT OR MUD TO GO DOWN THE DRAIN - it will clog the pipes. To avoid getting grit and mud down the drain, we wash the rocks in a colander over a plastic bucket.

Now that you have washed the rocks, it is time to inspect them. You want to determine if they are ready to move on to STEP 2, or if another week in STEP 1 would improve their appearance. This is what most people do.

However, other people want to have more control over the tumbling process and only admit excellent rocks into STEP 2. These people sort their rocks into four categories:


They then repeat STEP 1 until they have enough nicely shaped rocks that are ready for STEP 2. People who follow this process produce really nice tumbled stones; however, this process is very time consuming.
washing tumbled stones
Here is some rock right out of STEP 1. Note how it is covered with a gray "mud." This mud is spent grit and tiny rock particles that were worn off of the rocks during tumbling. Wash the rocks thoroughly so none of this grit goes into STEP 2. We wash our rocks in a colander over a plastic bucket so none of the mud goes down the drain.

STEP 2 - Medium Grind

The second step of the four-step tumbling process is to run the rocks in the tumbler with medium grit. Before you begin it is extremely important to clean all of the coarse grit and rock mud from the rocks, from the tumbler barrel and from the barrel lid. It is very important to avoid having a few grains of coarse grit in the medium grind step.

Again, fill the barrel about 2/3 full of rough (if you don't have enough rough, use ceramic media or some rocks that need a little more tumbling to make up the volume). Then add two level tablespoons of medium grit (we use 110/220 grit or 150/220 grit silicon carbide) for each pound of rock. Then add water until the water line is just below the top of the rocks. Now tumble for seven days.

At the end of seven days, open the barrel and clean all of the grit from the rocks, barrel, and lid (don't let any grit go down the drain). At this point in the tumbling process, a dry rock should have a smooth frosted surface. Inspect the rocks, looking for any that are cracked or broken. If found, they are discarded or saved for the next time we run Step 1.
DO NOT pour down the drain
Rock mud should never be washed down a household drain. It can clog your plumbing system. We wash over a plastic bucket to keep the mud out of the drain.

STEP 3 - Fine Grind / Pre-polish

The third step of the four-step tumbling process is a week in a fine grit such as 600 grit or 500 grit silicon carbide. Begin with a barrel that is perfectly clean. Add rough to fill it about 2/3 full, add two level tablespoons of fine grit per pound of rock. Then add water until it fills the barrel up to just below the top of the rocks. Run this for about seven days, and then do a thorough cleaning of the rocks, the barrel, and the lid. Remove any rocks that have broken or show signs of fracturing. At this point in the process, the rocks should be extremely smooth and some of them might start to have a slight luster.
clean tumbler barrel
Be very clean! Before you replace the lid on your barrel, be sure that both the lid and the rim are perfectly clean. This will allow the lid to fit tightly and prevent leaks.

STEP 4 - Polish

Now you are down to the final step - the one that puts a bright shine onto your tumbled stones. Be sure that the rocks and the equipment are perfectly clean. (Some people have an extra barrel that they use only for the polishing step.) A few specks of grit could ruin a great polish.

Place the rocks in the barrel, add two level tablespoons of rock polish (we use aluminum oxide powder or TXP) per pound of rock, add water to just below the level of the rocks. Then, close the barrel and run for about seven days.

When you finish this step, your rocks should be bright and shiny. If they are, congratulations! Admire them for a while and share them with your friends.

If the stones have an extremely smooth surface but do not shine, they might need cleaned up using the burnishing step described below. If they have scratches on them, then you will need to go back to STEP 2 and repeat the medium grind, fine grind, and polishing steps.
burnishing tumbled stones
For burnishing we chop up a bar of Ivory Soap and add 1/2 tablespoon of soap slices for each pound of rock. See our video about burnishing polished stones.
Burnishing

Sometimes our stones are a little "hazy" when they come out of the polish, or small particles of polish are in micro-size crevices. We shine and clean them up by tumbling for a couple hours in soapy water. This is called "burnishing."

To burnish we place the stones in our polish barrel with the normal amount of water and then we add about 1/2 tablespoon of chopped "Ivory" bar soap for each pound of rock (we use "ORIGINAL" Ivory soap - don't use a soap with aloe or abrasive or any other additive). Burnishing usually makes the tumbled stones a little brighter, and sometimes it really kicks up the shine.
rock tumbler log
Print a copy of our free tumbling log and use it to keep your records.
rocktumbler.com/rock-tumbling-log.pdf

Keeping Records

We recommend keeping records of what you tumble, the amount of time, the amount of grit, the amount of media, and the results that you obtain. It is easy to forget what day you started the tumbler or what type of grit was used - especially if you are running multiple tumblers. Keeping records will keep you on track and provide a history that will help you learn. We record material tumbled, start date, abrasive used, media used, finishing date and duration, along with any comments or observations about the results. To help you with your record keeping, we have prepared a printable tumbling log.

We keep records of the rock we tumble. Even if your memory is better than ours, this is a good idea. When you learn about something that works or something that doesn't, you will have it recorded. This information can help you repeat great results and avoid bad ones. Also, we have trouble remembering which day a barrel of rocks was started. With a log we can be reminded with a glance.

New Method of Tumbling (From 1996)

New Method of Tumbling - by Al Nutile in Tulip City Conglomerate

The writer believes that the following idea can take much of the work from the popular method of tumbling.
All of the instructions we have seen state: “Wash stones and tumble very clean between each change of grit or final materials,” at the same time stating, “If liquid is too thick add some slurp or grit from previously used material.”

We know some will argue against our method, but here goes:
Don’t wash at all after each week of tumbling with grit! Start with #50 grit, tumbling a week. Then DON’T EMPTY THE TUMBLER, but add 5 teaspoons of new grit [one step finer] to the mixture in the three pound tumbler. Follow this procedure through #190, #320 and #600 grit.

Now [finally] thoroughly wash the stones and tumbler before pre-polish and final polishing.

For a really glossy finish, take one or more weeks [after washing out the polishing powder] adding three spoons of sugar, one spoon [level] of Cascade or All or any non-sudsing detergent and add about ten drops of muriatic acid, if you have some, let stand one minute - open, close tub, and tumble for a week.

We have run eleven tubs using this method and found that even ordinary sandstone comes out highly glossed.
Except for extra final steps, you save three washings and getting rid of the slurp each time. Saves time, work and mess, and still gets a better polish.

From Pickin's & Diggitis 7/96
via Rock Chips 6/00 & others