You don't need a workshop full of lapidary equipment to polish stones. As long as you have your trusty Dremel or any other rotary tool, you can polish your stone and make it shine.
So, without further ado, we'll show you how.
Before you begin, you must have the proper tools and protective equipment for the job.
As far as tools are concerned, you will need the following:
- A Dremel or other rotary tool
- Diamond wheels and cutters
- Drums or sanding discs up to 1000 grit
- A felt polishing wheel
- Rock polishing compound
Choosing the Dremel for stone work
My top choice for the lapidary: The Dremel 4300 high performance with LED lighting
Any Dremel or rotary tool you have on hand is capable of polishing a stone with the right accessories.
Here are some recommendations if you are looking to buy a rotary tool:
The first is to make sure it has variable speeds. Stone work is done at low rpm, and a high-low switch or single-speed motor will make things more difficult.
You should also look for a model that is compatible with a flexible shaft. Dremel makes a branded one for their tools and they work better than a standard configuration. You can eliminate the risk of electric shock by placing the Dremel away from your water source while cutting. The handpiece is also more manageable than the rotary tool itself.
Cordless Dremels are popular, but a long job may require more than one charge. If you've never worked with stone, you'll find that extensive work is much smaller than you think.
Protecting yourself during polishing
Polishing stones is a bit dangerous, even if you work by hand. Your Dremel will throw up a lot of dust, and the dust is bad for your lungs.
In some cases, like agate, you will create ultrafine particles of silica that can lead to silicosis over time. Others may have more immediate consequences, such as the arsenic in bumblebee jasper. In any case, it is best to avoid dust as much as possible.
The area where you are working should be well ventilated. Being outdoors is preferable, but not possible for everyone.
You should also use a mask, even if you are working outdoors. Don't use a regular dust mask, they are designed for sawdust and large particles. You need at least one N95 class maskIt is best to use a half-face respirator with the appropriate filters.
To keep the dust level low, you need to work with wet stones. You can use a drip system or dip the stone in water several times. If you have access to a flexible shaft for your Dremel, you can work them directly in water.
If you are using a corded Dremel, be careful. Even if you're far from the outlet, it's a good idea to create a drip loop to prevent water from running down the cord. Just make sure there is a looped segment lower than the plug.
Safety glasses are a must. The stones can chip unexpectedly and the resulting stone can damage your eyes. Use an approved pair.
If something hits your glasses, don't touch your eye. Stone chips will cause much more damage. Open your eyelids before hitting the back of your head. It's a little painful but it works. If it doesn't, go to the local emergency room.
This is not a particularly dangerous task, the risks are easily avoided with basic protective equipment. As long as you have a mask and goggles, you're good to go!
If you have gathered your tools and PPE, you are ready to begin.
How to polish stones with a Dremel?
Step 1: Clean your stones
If you have not already done so, you must clean your stones.
Since we will be sanding, and eventually grinding, the stone, it is not important to make it shine. The dust on the stone is more dangerous than any dirt your Dremel 4000 tool could send into the air.
A bucket with warm soapy water and a wire brush will do the trick. For soft stones, a stiff nylon brush may be preferable. On the other hand, you'll rectify any surface scratches that a wire brush might create.
Pay particular attention to the deepest crevices. The accumulation of dirt can hide fractures that need to be rectified.
Once they are clean, it's time to move on.
Step 2: Grind to shape
Diamond wheels and cutters will allow you to shape the stone.
Keeping the stone wet, grind it into a rough shape. You can hold the small stones in your hand if you are careful with the Dremel, the larger stones must be held in a vice.
Grinding quickly removes water from the surface of the stone. You will need to wet the piece frequently, otherwise it will start to throw up a lot of dust. It may be tempting to just grind through, but you'll get a rougher finish and do some damage.
For those simply looking for a "rough" look, this step will take less time. Use the ball cutters to open crevices and eliminate cracks, and use the grinders to remove sharp corners and eliminate cracked material. This last point is important: you may lose some stone, but a heavily cracked piece will break in your hands when you move on to sanding.
When grinding, you should use a low speed on your tool. A lower speed is usually better, but you'll be fine as long as the bit doesn't throw mud. If a stone becomes too hot to handle, it is a good sign to reduce the speed.
Apply light pressure. Diamond bits burn quickly when you push them in. Light pressure and low rpm will make them last much longer. But even with the best practices, diamond bits wear out. Sooner or later, the grit wears out or the diamonds burn out.
Some people cut cabochons with a Dremel. That's a little outside the scope of this article, but all you need is a set of diamond cutting discs. Most cabochons will go through a more intensive shaping and polishing process, but the basics are the same as polishing.
If you are not carving a particular shape, the most important thing is that the crumbly parts of the stone are removed by sanding. After that, it's just a matter of aesthetics.
Once you are satisfied with the shape of your stoneYou are ready to move on to the next step.
Step 3: Sanding the stone
Sanding stone is a matter of patience.
Start with a small grain size, around 400Use a low grit until you have sanded the stone to your liking. Any lower grit value will remove a lot of material, a 200 grit disc may still be suitable but less is not recommended. Go back to diamond if 200 grit is not enough to get the desired result.
The next step is to evenly smooth the surface of the entire stone. This can take a long time depending on the size of the stone, but you must work methodically.
Letting the stone dry and removing dust with a microfiber cloth is a good way to know if it's time to upgrade to a higher grit.
For a complete beginner, I recommend covering the entire stone with a Sharpie or other black marker. The ultra-thin layer of ink will come off easily, and you'll know you've sanded that part of the stone.
Lower grits will leave visible scratch marks. It disappears with the next grain and is a reliable indicator of the state of progress of the work.
Keep the stone wet during sanding. Soak the stone as soon as you see dust starting to come off.
Gradually move to higher grits. Most sanding discs are spaced at 200 grit, which is ideal. Go from 400 to 1000 or 1200 depending on what you have on hand.
Optional: hand sanding
For a better finish, you can also sand the stone by hand once you have passed the 1000 grit and before polishing. We recommend it for cabochons, but it is not necessary for polished pieces.
Start hand sanding at 1500 or 2000 grit. You can find sandpaper up to 5000 grit online, but most hardware stores don't go over 3000 grit.
Hand sanding can be tedious, but simply switch to the highest grit you have available. At this point, you'll typically increase from 500 to 1000 grit between each pass. Expect to spend at least a few minutes with each grit.
You don't need to go over 2500 grains in most cases, but it is an option for perfectionists.
Step 4: Final polishing
Once the stone is properly sanded, you can proceed to the final polish.
You must remove the sanding dust before continuing. It can cause small scratches on the surface of your stone as the grit moves around. A microfiber cloth is good for removing the fine dust on the stone after sanding.
For most stones, the recommended compound is cerium oxide. It is most often found in powder form. You will need to create a paste to apply to your wheel.
Simply mix it with a little water to apply it. If you don't have a felt polishing wheel for your Dremel, you can also apply this paste to a piece of cloth for polishing. Polishing by hand, however, is...strenuous, and it won't give better results.
Use the Dremel at a slow speedYou do not need to spray the paste everywhere. Apply it to the stone and move the wheel over the surface. It is better to make small circles with the wheel rather than trying to move it in a straight line.
Once once the polishing is done, you will have a piece you can be proud of!