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| This turned object is large enough for the author to take advantage of power sanding. She wears a dust mask and runs her dust collector while sanding. |
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Let's face it, sanding is not fun. It's boring and tedious. But since it's a necessary step in most woodturning projects, especially bowl turning, it's worthwhile to learn as much about it as possible. Just a few extra minutes on the sanding stage can make the difference between a fair project and an excellent one.
There are two categories of sanding: power sanding and hand sanding. Additionally, there are significant differences between sanding bowls and sanding spindle work. The majority of my comments will address the sanding of bowls. Spindle sanding is easier. Or it should be, anyway!
Selecting Sandpaper
Not all abrasive paper is created equal. Like most things in life, you get what you pay for. Higher-priced abrasives work quicker and better than cheap ones. I recently discovered 3M's new product, advertised to last three times longer and work three times faster. It was also three times more expensive. Someone gave me some free samples, and when I ran out of my regular stock, I gave it a try. I was amazed. I now have my own stockpile of this time-saving abrasive.
Hand Sanding
The first step for hand sanding is to acquire decent abrasives, more generally known as sandpaper. Cloth-backed or paper is fine. Or you could buy rolls of those narrow strips. In the past, I have ordered and enjoyed a box of cloth-backed cutoffs from sanding belts.
As you complete the turning of your bowl, be sure you've ended up with the cleanest cut possible before you start sanding. This will make the process go much more quickly. If your bowl is small or concave, you will have to hand-sand it. I will discuss that process first, as it applies to sanding dry wood.
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| Folding a small piece of sandpaper in thirds before using it on your turned object may seem like a minor thing, but it's a very effective strategy. |
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First, fold a small piece of sandpaper in thirds. This may seem like a minor requirement, but it's based on sound advice. First of all, if you use a large section of abrasive in a small curved bowl, you won't be able to conform the paper to the curves. And second, folding the paper in thirds keeps it from slipping, because smooth back will not be positioned against smooth back. And finally, this approach also keeps your paper from rubbing and wearing out, because abrasive doesn't touch abrasive. If your fingers are sensitive, use a foam backing behind the folded sandpaper.
Slow down the speed of the lathe. Turned bowls quickly warp just enough to become somewhat oval. Sanding at a slow speed will allow your handheld paper to touch the entire inside and outside of the bowl as it rotates. If the lathe is running fast, you'll hydroplane, and your abrasive will only touch part of the bowl. In addition, the part of the piece you're touching isn't even the part that needs sanding!
You will most likely need to start with 80- or 100-grit paper for hand-sanding a bowl. At times in the past, I've been known to resort to 60-grit, but now that my turning techniques are improved, even 80-grit usage is rare. After completely removing all tool marks, proceed to the next finer grit. A good rule of thumb is 80-, 100-, 150-, 220-, 320-grit. Don't skip a grit.
Sanding creates a lot of fine sawdust. Wear a mask and have an air filter of some sort running. Another way to decrease the amount of dust is to wet sand. Water works great for this! I've tried several varieties of homemade sanding gunk, but water's the best. Simply moisten a small piece of cloth, then moisten the inside of your bowl. This will magically decrease your sanding time, plus decrease the dust in the air. Yes, it will clog your paper, but in my opinion, the tradeoff (we're talking about your lungs here) is worth a bit of extra expense.
As you progress through each grit of abrasive, you leave behind bits of abrasive imbedded in the grain of the wood. This occasionally causes a major sanding scratch to appear while you are sanding at 220-grit. Several processes help to avoid this occurrence. If your lathe can be reversed, then reverse directions at 150-grit and sand both forward and backward. This will help remove those imbedded coarser abrasives. Another option is the wet sanding already mentioned above. It will raise the grain, helping to release imbedded grits. A third method is to sand by hand, with the lathe off and the bowl still attached. At the 150-grit stage, quickly go over the entire surface with 150-grit. It takes a few minutes, but in the end, it can save time.
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| This turned cherrywood bowl is so small that it requires the hand-sanding with a small piece of abrasive. Remember, friction can create heat in a hurry• watch the pressure. |
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Another common sanding annoyance is the small nub often left in the center of bowls and platters. While it might not have been there after the turning stage, it can appear because of the sanding process, especially if you've done a lot of sanding. You can eliminate these nubs in one of two ways: hand-sand with sandpaper wrapped around a small, flat block of wood or compensate for this phenomenon by turning the center of the bowl just slightly dimpled. By the time you're finished sanding, it's flat.
When you think you're finished sanding, and you take your bowl off the lathe and hold it up to the sunlight, you might discover sanding scratches on the endgrain sections of the bowl. These can be minimized by sanding to a finer grit. Put the bowl back on the lathe and sand to 1,200-grit or even finer. Another option is to use fine or super-fine foam-backed sanding pads and sand your bowl with the lathe off. It only takes a few minutes.
Power Sanding
Power sanding is a much quicker process, but it has its own problems. Also, you can use the process only on bowls large enough to accommodate the discs. Fortunately, some of the newer products have helped decrease these problems. Power sanding can be accomplished using an angle drill with a sanding disc holder attached or by using a handheld rotating sanding device. I've not used one of those non-electric gadgets, but other turners I know have and they swear by them. For power sanding, you can usually start with 120-grit abrasive. It only takes a minute or two to sand an entire bowl or platter with each grit.
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| Sanding discs and interface pads come in a wide variety of sizes and types, including foam-backed and wave-type. Interface backing pads are inexpensive and help to extend the life of the more expensive sanding disc holders. |
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Progress through each grit to finer and finer. A good progression is 120-, 220-, 320- to 400-grit. And you can go finer and finer. As you do, the swirl marks diminish. After sanding, you can buff to get rid of remaining sanding swirls, but since I don't care for that much of a shine, I usually hand-sand off the lathe with fine foam-backed abrasive. I like to use the interface backing pads. They're inexpensive and help extend the life of your expensive sanding disc holders. The thick, foam interface pads are great for sanding curves, both interior and exterior. For some sanding tasks, I use the wave-type sanding abrasives. They can help decrease the dig-in that sometimes happens with sharp-edged sanding discs.
When you are power sanding, take care to not over-sand. Run your lathe slowly. This truly is a fast process; if you're spending more than a few minutes, you're over-sanding.
Sanding Spindles
Spindle sanding should be minimal if you are cutting the wood properly to begin with. The tops and bottoms of areas like beads and coves should be the only areas that might need a bit of touchup, and then only with 150- or finer grit to start with. Over-sanding spindle turnings causes the elements to be less crisp and to run together. You can sand spindles at a relatively high speed, but it's also all right to slow down your lathe.
If you intend to paint the surface of a turned spindle, then sanding with 150-grit is recommended, but don't sand below 220-grit. Paint adheres better to a slightly sanded surface than to a burnished surface.
For sanding a spindle like a pen, I recommend a bit of hand-sanding at 320-grit so that you don't end up over-sanding. Use a foam-backed, fine-grit pad, and sand in the direction of the grain. Any minor sanding scratches will run with the grain of the wood and not be noticeable. You can then buff the wood to give it a shine.
Sanding Safety
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A few words about safety and sanding. It is potentially a dangerous process. Always remove the toolrest before sanding. I guarantee that you don't want to get your fingers caught between the wood and the toolrest! If you use any type of rag for wetting the wood or for holding the sand paper, be sure that it's a small piece of cloth. Long, loose pieces of cloth can get caught in rotating wood, dragging your fingers into the fray. Of course, by now you know to not wear loose clothing! Only recently an acquaintance of mine injured his whole arm when his sleeve was caught and his arm was dragged into a turning spindle while he was sanding.
Now that you're equipped with a bit more information on sanding techniques, the final step is to decide to implement them. Once you make up your mind to give it a try, I guarantee the rest is easy.