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Select the proper sandpaper for the job
Dear Ms. Builder: I moved into an older house that I plan to fix up myself. It has beautiful natural woodwork that needs refinishing. I am confused about what sandpaper to use and when. What paper is best? - Connie P.
Dear Connie: When you go to a home center or major hardware store and finally find the sandpaper aisle, the choices are staggering and confusing. Each package is listed with much nomenclature, specifications and plain old marketing hype. It can be truly overwhelming and confusing.
Although this is probably not what you want to hear, there really is not one best type of sandpaper for all jobs. The most effective type depends on the material that you plan to sand and the end result that you desire. In your case, you probably want a professional-looking slick glossy finish.
The first major categories of sandpapers are open or closed paper. Open paper has only about 70% grit coverage which leaves spaces between the particles. This works well with wood. The open spaces keep the sandpaper from loading up and clogging with the wood dust. Closed sandpaper is better for use on metal or other hard materials.
Next you must determine the grit to buy. A smaller grit number means a larger, more coarse grit size. The number refers to the number of holes per sq. inch in a sieve. In order to get 220 holes per sq. inch, the holes must be smaller than in a 60 holes per sq. inch sieve. Smaller holes allow only smaller particles of abrasive to pass through.
You will often start out with a coarse 60-grit paper and sand across the wood grain. This removes a lot of wood quickly to remove any small nicks and scratches. Next you can use a 100-grit paper and sand with the grain.
Prior to finishing, use a 180-grit paper for a smooth surface. If you have plenty of time, light sanding with 220-grit paper will yield a glass-like surface. This is also a good grit to use between coats of urethane.
Your final selection decision is the type of grit. Sandpaper does not actually use sand. There are four basic abrasive grit materials and each has its specific advantages for various materials you are finishing.
Aluminum oxide is the most common material you will find and it is one of the best for use on raw and painted wood. It usually has a light brown color. It is inexpensive and as you use it, the aluminum oxide particles fracture. This is good because it continuously creates new sharp edges.
Red garnet is another grit material that is often used on wood, especially for the final finishing. It is orange or red in color. As you use it, the relatively soft abrasive particles tend to dull (not self-sharpening like aluminum oxide). This dulling makes it easier to get a mirrorlike surface on the wood prior to finishing with urethane.
The other two types of grit that you will find are silicone carbide (black) and ceramic (reddish brown). Silicone carbide, is very hard and self sharpens somewhat and is best for metals, plastics and other synthetic materials. Ceramic grit is most often used on power belt and pad sanders.
Although you mentioned only sandpaper, there are some fairly new sanding "sponges" that can be washed and reused many times. These are comfortable to the hand and are ideal for sanding wood with curved surfaces. Since they form to curved surfaces, they tend to provide a more uniform sanding action.
They sanding pads are available in many grits just like regular sandpaper. If you cannot find them, here are two companies that make them - Surehold (800-881-4495) and Norton (800-551-4415). Surehold also offers a special project kit that contains various grit sponge pads, glue, glue remover and a general-purpose file.
Send your questions to Ms. Builder, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com/msbuilder.