• Very five or soft papers, used by wood-finishers from 00000000, or 8/0, to 00, or 2/0

• Medium sizes, commonly used by woodworkers: 0, or 1/0, 1/2, 1, 1%, 2

• Very coarse papers, more commonly used on sanding machines for rapid cutting: 2 ½, 3, 3 ½, 4

Sizes finer than 8/0 sandpaper are made by some manufacturers, but are not commonly found on the market. Unfortunately, the sizes of sandpaper are not absolutely standardized, and one manufacturer's sizes may not correspond exactly with those of another. Similar to an architect's or contractor's unique tape measures, no steel tape measure is going to be exactly like it's steel tape measure counterpart.

The cardinal principle in the use of sandpaper is that all sanding must be with the grain. Never make circular, cross grain, nor oblique strokes with sandpaper, as scratches always result. The end grain of wood must be sanded crosswise.

A careful study of wood structure with a magnifier shows that the fibers are arranged like parallel tubes lengthwise of the grain. These fibers are scratched, torn, or cut thru by the sharp edges of the sand grit if the strokes are in any other direction than lengthwise of the grain.

Resanding with the grain in the proper way will not easily remove scratches. Such injuries should be scraped out, and after all scratches have disappeared, the surface should be sanded, pushing the sandpaper lengthwise of the grain of the wood with the appropriate tools, whether they are precision measurements tools or specific sanding tools.

Blocks for holding sandpaper in order that greater pressure may be applied are used in every finishing room. The size, weight, and covering for the blocks depend upon the kind of work being done. For big surfaces a rather large heavy block has some advantages. A brick covered with canvas or other cloth is used in some shops for coarse work, especially where rapid cutting on large surfaces is desired.

For the first sanding with coarse sandpaper some workmen prefer a hard flat block with little or no covering. Sandpaper over a hard block without covering, or with little covering, will cut off the .high spots better and help to reduce the somewhat irregular surface to a truer, leveler, or plane surface.

A favorite size of sandpaper for use on many kinds of wood for the first sanding is No. 1 or 1.5. For the finer-grained woods you should use the No. 1, which is finer than No. 1.5. The second sanding with finer paper can best be done with a soft block or a block with a soft cover. Some prefer to use corks about 1" x 3" x 6" in size. Another size sold on the market for such work is 1"x 4" x 4".

Felt-faced or cloth covered blackboard erasers can be used very satisfactorily for sanding-blocks. Some finishers use rubber faced blocks. A home-made block of this kind can be prepared from a rectangular scrap of soft wood to which you tack a piece of rubber taken from an automobile inner tube. The sizes of sandpaper used for fine sanding are about 1/2 or 0. Sometimes 00 papers are preferable for very fine-grained hardwood.

Rounding off the corners of a piece of wood in sanding is a very common fault that you must avoid or you will ruin the appearance of the finished work. This does not mean that the sharp feathered edges or arrises should not be slightly smoothed off to get rid of slivers, for this should always be done with fine sandpaper in the final sanding. Unless you take care to avoid a rocking motion while sanding, the corners and edges will become rounded off unevenly and unsightly disfigured work will be the result.

End grain sanding is just as important as sanding of the surfaces and edges. If the end grain is left too rough, additional stain will be absorbed there; consequently it will become darker than other portions of the surface regardless of pocket tape measures, logger tape measures, or any other unique tape measures used to try and avoid this.

Curved surfaces can be sanded to best advantage with split sandpaper. Double coated paper for splitting is widely available. The split sandpaper is most effective for some kinds of work when dampened or moistened on the back. Water, benzine, and turpentine, or turpentine substitutes, are used for moistening sandpaper either to keep down dust or to make the paper more pliable.