Burnishing Tumbled Stones or Glass in a Rock Tumbler
What is Burnishing?
Most stones or glass that have been processed in a rock tumbler look pretty good at the end of the polishing step. However, there
is one more short step that might significantly improve their luster and really make them shine. That step is known as “burnishing”.
It involves running the stones in a heavy soap bath for a couple of hours.
The Buffing Test
To determine if burnishing will improve the luster of your polished stones or tumbled glass or whatever you have tumbled you can perform the “buffing
test”. That involves rubbing one of the stones very rapidly on a soft piece of cloth. You can easily do that by rubbing it
on the sleeve of a flannel shirt or a t-shirt or a pair if jeans.
Pick a nice flat surface on one of your stones and study it for a moment to become familiar with its luster. Then rub it very
rapidly on the soft cloth for fifteen to twenty seconds - enough time to build up a little heat. Then examine the flat surface
to see if the luster improved. If it improved then a short burnishing should improve the luster of the rocks.
Preparing to Burnish
Place your polished stones in a perfectly clean tumbler barrel. Be sure that the barrel is 1/2 to 2/3 full. Add ceramic cylinders if you don’t
have enough material to fill the barrel or if you need small particles as cushioning between large rocks. If you are using
ceramic media be sure that it has been tumbled before. Brand new media often has some sharp edges that can scratch up your rocks. We usually add some plastic pellets to cushion the rocks while they are being burnished.
We use Ivory bar soap that has been cut into small pieces. We cut a few slices with a sharp knife and add about 1 tablespoon
of chopped soap per pound of rock. Some people use a powdered laundry detergent for burnishing. Tide and Ivory Snow powdered
detergents are reported to work well - about one teaspoon per pound of rocks.
The Burnishing Step
You don’t have to run the burnishing step for a whole week. A few hours or overnight should be long enough. Then open the tumbler
and clean up your rocks. Wow! They should look great!
In this video we
demonstrate how to do the burnishing step for tumbled rocks or tumbled glass. The burnishing step involves running the rocks
for a few hours in a heavy soap bath. It can really improve the luster of your polished stones.
For burnishing we chop up a bar of Ivory Soap and add one tablespoon of soap slices for each pound of rock. Lots of people use Tide or Ivory Snow powdered detergent - about one tablespoon of soap powder per pound of rock.
We highly recommend:
Modern Rock Tumbling by Steve Hart.
Learning is the fastest way to improve the quality of
rocks that you tumble. In this book you will learn from an expert with extensive
experience. You will increase your abilities, learn to save time, money and have a great reference book
that you will use again and again.
Gemstones of the World
We highly recommend:
Gemstones of the World (fifth edition) by Walter Schumann.
One of the most popular gemstone books ever written, with over one million copies sold. It has about 100 pages of basic gemstone information and about 200 pages dedicated to photos and descriptions of over 100 gems and gem materials.