~ Studio 182 Lapidary ~

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Tumble Polishing Process

Getting started:

Tools & material needed:

Tumblers.

Single Barrel or Multi-barrel:

Rotating Tumblers
The toy stores carry a type of rotating tumbler, where the rocks fall over and over and over, polishing rocks in much the same manner as the ocean has for millions of years. I recommend buying a tumbler from a company that has been around a while, with an established record of quality and service. Eventually, you will need a replacement part; you want the company to still be there when that happens. Lortone offers several sizes of tumblers, some with double barrels.

Vibrational 'Tumblers'

 
Vibrational or agitating tumblers don't actually tumble the rock, but use either ultrasound or spin around the vertical axis. They cost a bit more, but have two characteristics that make them more desirable for certain users: they polish rocks much more quickly and they retain the essential shape of the rocks rather than producing only rounded rocks. They are a bit quieter, too. Raytech is an established manufacturer of vibrational tumblers (and other lapidary equipment).

Tools & materials:

Ivory Soap:

Ivory soap placed into the Tumbling barrel creates a slurry which helps uniformly suspend the Grit, increasing its cutting action.

If using the Bar Soap, cut chunks into approximately 3/8” cubes and place 1 cube in barrel for each 1.5 lbs. of Rock.

If using the Liquid soap, put 3 to 4 drops for each 1.5 lbs. of Rock.

DO NOT put too much soap in the mixture as it will buildup pressure and unseat the Barrel Seal causing leakage.

IVORY SOAP DOES NOT contain any ingredients which will harm the polishing process as other soap products may.

White Rice:

 Use plain white rice in with the stones for the last polishing. This will do a wonderful job and the rice will keep the stones from chipping.

Disposable Plastic spoons.

 Used for Grit handling and miscellaneous cleanup processes.

Plastic strainer:

 Use for cleaning and draining Gemstones during the Polishing Processes. Metal strainer should not be used as it may damage stones during the cleaning process.

Measuring cups:

 Used for measuring materials required during the Polishing Process.

Washed River Sand:

  One bag of washed River Sand used for initial rock cleaning process. Can be purchased at your local Home Improvement Store.

  Silicon Carbide Grit:

  You will need several sizes of silicon carbide grit to accomplish the polishing process. Always clean your rock from all grit after each cycle.

Grit size:

• #100 grit 1 lb. for each 8 pounds of rock
• #220 grit 1 lb. for each 8 pounds of rock
• #600 grit  3/4 lb. for each 8 pounds of rock

Polishing Powder:

  Tin Oxide: It's recommended as a final polish. This is a good general polishing powder used throughout the industry. Amount recommended is 3/4 lb. for each 8 pounds of rock

Preparing your stones:

Visit our Tumbling Gemstone Gallery at: www.studio182.com 

Cleaning your Stones:

Place your stones in the tumbling barrel until the barrel is ½ full. Add clean river sand until the barrel is loosely ¾ full. Add your soap and add water until the sand is just covered. Seal the barrel and tumble for at least 4 hours. This will remove any soft material and primeval ooze. Remove the stones after the cleaning process and inspect for cleanliness. If not acceptable, continue tumbling. If acceptable, place stones in plastic strainer and garden hose clean removing all  contaminants.

Stone hardness:

The Mohs scale was devised by Friedrich Mohs in 1812 (and therefore it's never spelled "Moh's"). You use the Mohs scale by testing your unknown mineral against one of these standard minerals. Whichever one scratches the other is harder, and if both scratch each other they are both the same hardness.

The Mohs scale is strictly a relative scale, but that's all that anyone needs. In terms of absolute hardness, diamond (hardness 10) actually is 4 times harder than corundum (hardness 9) and 6 times harder than topaz (hardness 8). Because it isn't made for that kind of precision, the Mohs scale uses half-numbers for in-between harnesses’. For instance, dolomite, which scratches calcite but not fluorite, has a Mohs hardness of 3½ or 3.5.

There are a few handy objects that also fit in the Mohs scale. A fingernail is 2½, a penny (actually, any current U.S. coin) is just under 3, a knife blade is 5½, glass is 5½, and a good steel file is 6½. Common sandpaper uses artificial corundum and is hardness 9; garnet paper is 7½.

Mohs hardness is just one aspect of identifying minerals. Along with Mohs hardness, you need to consider luster, cleavage, crystalline form, color, and rock type to zero in on an exact identification.

Sorting:

Sort your stones by Hardness and size. A load of Stones should all be approximately the same size and also the same MOHS Hardness. Stones the same size get a more uniform action when tumbling. Tumbling hard stones with soft stones will result in the soft stones grinding faster than the harder stones. This may result in under worked stones with over worked softer stones being rendered unusable.

Tumbling Process

There is several 4-step media packages available to use with your tumbler. Each of the four steps requires one week or more to complete the tumbling cycle.Always clean your rock from all grit after each cycle.

Clean the stones.

Place your stones in the tumbling barrel until the barrel is ½ full. Add clean river sand until the barrel is loosely ¾ full. Add your soap and add water until the sand is just covered. Seal the barrel and tumble for at least 4 hours. This will remove any soft material and primeval ooze. Remove the stones after the cleaning process and inspect for cleanliness and condition. If not acceptable, continue tumbling. If acceptable, place stones in plastic strainer and, using a garden hose, clean stones removing all contaminants.

Rough Grinding:

Place the cleaned stones in a CLEAN barrel, the barrel should be ¾ full, with #100 Grit. Grit to stone ratio should be 1 pound of Grit for each 8 pounds of stone.  So a 1.5 lb. load of stone would take 3/8 Lb. (6 oz.) of Grit. Add soap and water until the contents are just covered.NOTE: Too much water decreases the Grits cutting action.Run Tumbler for 3 days and check contents for adequate liquid. Run 3 more days. Check liquid and grit condition. If grit appears to be breaking down, add 1 plastic spoon full of new grit & adjust water level. Continue this process until your Stones are ground to the desired shape and smoothness. Remove stones, clean the barrel and repeat step 1(clean stones) without using the River sand.

Always clean your Rock & Barrels from all grit after each cycle. Failure to do so will result in cross contamination and will ruin the next step of the polishing process.

Do not pour Grit into plumbing. Grit will harden into concrete and plug up any plumbing.

Medium Grinding:

Place the cleaned stones in a CLEAN barrel. The barrel should be ¾ full, with #220 Grit. Grit to stone ratio should be 1 pound of Grit for each 8 pounds of stone.  So a 1.5 lb. load of stone would take 3/8 Lb. (6 oz.) of Grit. Add soap and water until the contents are just covered. Run Tumbler for 3 days and check contents for adequate liquid. Run 3 more days. Check liquid and grit condition. If grit appears to be breaking down, add 1 plastic spoon full of new grit & adjust water level. Continue this process until your Stones have smoothed out all of the #100 Grit marks. Remove stones, clean the barrel and repeat step 1(clean stones) without using the River sand.

Always clean your Rock & Barrels from all grit after each cycle. Failure to do so will result in cross contamination and will ruin the next step of the polishing process.

Do not pour Grit into plumbing. Grit will harden into concrete and plug up any plumbing.

Pre polish:

Place the cleaned stones in a CLEAN barrel, the barrel should be ¾ full, with #600 Grit. Grit to stone ratio should be 3/4 pound of Grit for each 8 pounds of stone.  So a 1.5 lb. load of stone would take 1.5 oz. of Grit. Add soap and water until the contents are just covered. Run Tumbler for 3 days and check contents for adequate liquid. Run 3 more days. Check liquid and grit condition. If grit appears to be breaking down, add 1 plastic spoon full of new grit & adjust water level. Continue this process until your Stones have smoothed out all of the #220 Grit marks. Remove stones, clean the barrel and repeat step 1(clean stones) without using the River sand.

Always clean your Rock & Barrels from all grit after each cycle. Failure to do so will result in cross contamination and will ruin the next step of the polishing process.

Do not pour Grit into plumbing. Grit will harden into concrete and plug up any plumbing.

Polishing:

  Place the cleaned stones in a CLEAN barrel, The barrel should be ¾ full, with #600 Grit, Stones & White Rice. Grit to stone ratio should be 3/4 pound of Grit for each 8 pounds of stone.  So a 1.5 lb. load of stone would take 1.5 oz. of Grit. Add water until the contents are just covered. DO NOT add soap to contents. Run Tumbler for 3 days and check contents for adequate liquid. Run 3 more days. Check liquid and grit condition. If grit appears to be breaking down, add 1 plastic spoon full of new grit & adjust water level. Continue this process until your Stones reach the desired quality of polishing. Remove stones, clean the barrel and repeat step 1(clean stones) without using the River sand.

Always clean your Rock & Barrels from all grit after each cycle. Failure to do so will result in cross contamination and will ruin the next step of the polishing process.

Do not pour Grit into plumbing. Grit will harden into concrete and plug up any plumbing.

Visit us at www.studio182.com for your Lapidary needs.

Tumbling rough

Cabochon slabs

Rough for tumbling or cutting