One important skill in wood finishing is the ability to conduct a careful inspection of a surface that needs to be sanded. If rough spots or planer marks have been left they should be found and removed before you attempt any sanding. Hand sandpapering will not remove or cover up defects of this kind. It is a useless waste of time and energy.

Scraping out unfinished places later on is more difficult. Sandpapering always leaves sand in the pores of the wood. This sharp grit soon dulls the edge of a scraper-blade. The hook on the scraper blade must be sharpened frequently if it is used on a surface that has been sanded recently.

Amateur wood-finishers should learn what defects to look for on the surface of the wood. Planer marks and minor blemishes that hardly show on the natural wood are greatly exaggerated on the finished piece, especially when finished with a wood stain.

Bough surfaces almost always expose more cross sections of the pores or end grain, which, when stained, appears darker than the rest of the surface. This is due to the fact that the end grain of wood is more porous than the ordinary grain of longitudinal or transverse sections. Keep this in mind if you are using boughs for railings, especially wooden bar rails. This also applies to wooden bar cabinets and other medium sized items.

Modern day sand paper is not literally made from sand and paper. The grit which looks like sand is made from quartz or flint rocks. The red or garnet papers have a grit made from garnet ore. Great hardness and the sharpness of the edges are important factors in grit. Natural sand, while hard, has very few sharp edges. All such cutting places are soon worn off and smoothed by the grains rubbing against each other, just as rocks on the mountainsides are smoothed and rounded by glacial action.

Sharp grit is made from crushing hard rock and sifting in order to secure particles of uniform size. Various sizes of rock fragments, sometimes called sand, are secured in order that
sandpaper of different grades of coarseness and fineness may be manufactured.

The best grades of paper are strong, especially when made from Manila fiber, which is sometimes secured from old ropes. The strength is increased by a crisscross or uneven composition. Papers that are made so that the fibers are not parallel with their lengths in one direction are stronger crosswise and have nearly uniform strength in every direction. Such papers are difficult to tear and, if torn, leave a rough, uneven edge.

Thicker papers are used when coarser grits are needed. In the manufacture of sandpaper, rolls of paper are run through a machine, unwinding and passing along as in a printing press. Hot glue of a good grade is spread evenly over one side of the paper. The sand is then sprinkled to a uniform thickness over the surface, and the excess grit, which does not become set in glue, finally disappears falling off after the paper turns over a roller.

In order to make sure that the sand will stick to the paper more glue, a thin solution is applied and then a drying process with a hot blast starts. When the glue becomes set or practically
dry the paper is rolled up, or cut into sheets of standard sizes. These sheets can also be cut especially for automatic sanders. Automatic sanders are good for larger objects like desks, wood burning stove fireplace inserts, cabinets, wood fireplace inserts, rocking chairs, and jotul wood fireplace inserts.

Some manufacturers are now producing a new type of double-coated paper, known as split sandpaper, which has a layer of sand or grit on both sides. This paper will easily split apart, leaving two sheets of sandpaper, each being very thin and flexible. Such an abrasive is excellent for smoothing curved surfaces, because it can be more easily bent over one's hand or in a curved form than is the case with ordinary sandpaper.

The Wetordry Garnet Finishing Paper is another type of sandpaper that has some excellent features very desirable in wood finishing. This paper is waterproof, and can be used to great advantage over a wet felt pad. The finer grades of Wetordry sandpaper, such as the 5/0 to 8/0 sizes are excellent for sanding varnish between coats. A varnish surface smoothed with one of these papers having the finest grit looks much like a finish rubbed with pumice-stone and
the operation can be completed in much less time.