#Obsidian igneous rock full#

#Obsidian igneous rock full#

If you would like to try burnishing to see if it improves the look of your polished stones, full burnishing instructions can be found here.įinished Snowflake Obsidian Tumbled Stones: However, burnishing this material after the polish step can often improve the look of the finished stones. This rough will usually take a great polish. We have found that 48 hours is usually all the time you need to get a good polish on this material in a vibratory tumbler.

Like the previous grit steps, open the bowl every 8-12 hours to check the tumbling action. Stop adding water when the material has a thin coat of wet polish and the tumbling action is smooth and rapid. Turn on the tumbler and slowly add water. Add one tablespoon of grit for every two pounds of material in the bowl. If needed, add ceramic media that has been previously polished, to bring the bowl up to the manufacturer's recommended operating level. Place the cleaned material back in the bowl. Thoroughly clean the bowl and material before moving to the polishing step. Open the bowl every 8-12 hours to check that the action is still good. Then, turn the tumbler on and slowly add water until the material has a thin coat of wet grit and the tumbling action is smooth and fast in the bowl. This will also get you near the recommended 50% ceramic media. Place your material back in the tumbler bowl, then add enough polished ceramic media to bring the load up to the manufacturer's recommended operating level. Give the material and bowl a thorough cleaning before moving on to fine grit. Usually 2-3 days for us with this material. You are done with medium grit when you are satisfied with the shape and smoothness of the stones. After rinsing, add fresh grit and water and start tumbling again. If the mud gets too thick, you will need to do a complete rinse of the material and bowl. If the action has slowed, add water a little at a time until the action is back to normal. While the tumbler is running, slowly add water until the material has a thin coat of wet grit and the tumbling action is smooth and fast in the bowl.Ĭheck the bowl every 8-12 hours to ensure that the action is still good. Also, the more media, the better the cushioning.Īfter you have your bowl loaded to the manufacturer's recommended level, add 1 tablespoon of grit for every two pounds of material, including the media, in the bowl. The use of this media will aid in the tumbling action in the barrel and help deliver grit to all surfaces of the rough. It is recommended that you use a minimum of 50% ceramic media. Obsidian is a fragile material that can easily be bruised or chipped. The many small pieces of media will also reduce the impact forces that occur in the barrel and deliver grit to all surfaces of the rough.Ĭoarse grit is not used in a vibrating rock tumbler. The cylindrical shape of the ceramic media enables it to act like roller bearings and provide a smooth tumbling action in the barrel. We use at least 50% ceramic cylinder media and 50% obsidian. To prevent bruising, it should be swimming in a sea of small ceramic cylinder media. Polishing time is not changed.ģ) Media Needed: Obsidian bruises easily. We also reduce the time in fine grit (500 mesh) to 5 days. Instead of two weeks in 150/220 grit, we reduce that to 5 to 8 days.

So we skip the coarse grit step and begin our tumbling with medium grit (150/220 mesh).Ģ) Less Time: We also shorten the tumbling time in the first step. To accommodate these properties we do three things: 1) skip the coarse grit step 2) tumble for a shorter amount of time 3) add plenty of media for cushioning.ġ) Skip Coarse Grit: Coarse grit will quickly reduce the size of obsidian. Obsidian also bruises easily if it is not cushioned.

That is softer than most types of rocks that are processed in a rock tumbler. These pieces of obsidian are about 1/2 to 2 inches in size and have a Mohs hardness of about 5 1/2. It produces an excellent polish in six to seven days in rotary. We always use TXP aluminum oxide polish when tumbling obsidian. Then about four or five days in fine grit will have it ready to polish. One week in a rotary tumbler in medium grit is enough time to round off all of the sharp edges and produce nicely rounded stones.

That enables it to shape quickly in a rock tumbler. It is quite a bit softer than agate and jasper. Obsidian has a Mohs hardness of about 5 1/2 to 6. As you can see, the jet-black tumbled stones have a nice 'glassy' shine. Here are a few pieces of plain black obsidian that we tumbled.