Sanding surfaces

 

Sanding serves to remove imperfections on walls, ceilings, furniture, floors, etc.

Sanding serves to remove imperfections on walls, ceilings, furniture, floors, etc. It is also used to roughen surfaces too glossy for paint or filling compound to adhere easily. Steel wool and sandpaper are the most commonly used abrasive materials for this purpose. Sanding can be performed by hand or with electric tools.

Learn how to:

Tools and products for sanding

Steel wool

Steel wool is used for cleaning, stripping and polishing metals, wood, etc. Types of steel, bronze and copper-based wool are good for surfaces exposed to water. You can use them to sand wood if you apply water-based or micro porous finishing products. Other types of steel wool leave traces that could imbed themselves in the wood and rust on contact with water.

The degree of roughness in steel wool range from extra-coarse (4) to extra-fine (0000). Very coarse wool (3) is used to smooth rough surfaces and remove varnish or paint during stripping. Coarse wool (2) is used to remove old paint and rust. When soaked with solvent, it easily removes grease and wax. Fine wool (0) is used to clean painted surfaces, trim and floors. Extra-fine wool (0000) is used to rubdown paint, varnish and shellac before applying a final coat. It also serves to polish surfaces and give them a satin finish.


Sandpaper

Sandpaper consists of grains of aluminum oxide, emery, garnet, or silicon carbide glued to a backing. This backing may be paper, cloth, fibre, plastic or a combination of paper and cloth. The grains may be open or closed. Closed grains crush more easily during use. Sandpaper comes in sheets, belts and disks and in various grades of coarseness.

The coarseness of certain types of sandpaper is graded from 12 to 600. The higher the number, the smaller the grains. Other kinds of sandpaper come in three grades: coarse, medium and fine. The type of surface and its condition determine which grade should be used. Coarse paper is used to make rough surfaces smooth as quickly as possible. Finer paper is used to eliminate traces of the coarser grades. The following two charts present the main types of sandpaper and their different uses.


Main types of sandpaper

Aluminum oxide Tough synthetic abrasive. Its grains break during sanding, thus restoring coarseness. It is used to smooth and strip bare metals and wood.
Silicon carbide Synthetic abrasive. Its grains wear down during sanding. Used for sanding gypsum (drywall), synthetic surfaces and concrete and also applied between coats of paint or finish.
Emery Fine and natural abrasive glued to cloth and used on metal.
Garnet Natural abrasive, the grains of which wear down during sanding. Use to sand bare wood.

Different uses for sandpaper

Use

Coarseness

To remove old finishes 60-80
For bare wood 80-120
Plastic, ceramics, melamine, Formica, metal and stone 100-150
Between coats of paint 120-220
Before applying stain inside (water-based) 180-220
Before applying stain inside (solvent-based) 120-220
Before applying stain outside 80
Old stained or varnished wood that is still in good shape 220
Between coats of varnish 220-320

Before you start sanding, make sure you are using the right sandpaper for the job by testing it on a hidden patch of the surface. Use a sanding block appropriate to the surface if you plan to sand by hand. The block helps you apply even pressure across the surface and so makes sanding easier. You can buy such a block or make one yourself with a properly sized piece of wood.

Electric sanders

Electric sanders are faster and often more effective than hand tools when doing a large quantity of work, but they also require more skill. These tools include belt sanders, vibrating sanders, disk sanders and floor sanders.

Sanding wooden surfaces:

Checklist

  • Sandpaper
  • Sanding block
  • Electric sanders
  • Shop vacuum cleaner
  • Protective goggles
  • Filter mask
  1. Start with a coarse aluminum oxide or garnet sandpaper and end with a finer (80, 120, 180, 220) sandpaper.
  2. Sand with the grain to avoid ripping the wood fibres.
  3. Vacuum up the dust.


Sanding masonry:

Checklist

  • Sandpaper
  • Sanding block
  • Electric sanders
  • Dry white rag
  • Shop vacuum cleaner
  • Protective goggles
  • Filter mask
  1. Start with a coarse silicon carbide sandpaper and end with a finer (100-150) sandpaper.
  2. Sand in a circular motion.
  3. Vacuum up dust.
  4. Wipe with a white, moist, lint-free rag. The moist rag removes any dust left by the vacuum cleaner. Soak rag in clean lukewarm water and wring out thoroughly before wiping to avoid leaving behind any moisture that could cause wood to swell.

Sanding previously painted surfaces:

Checklist

  • Sandpaper
  • Sanding block
  • Electric sanders
  • Shop vacuum cleaner
  • Protective goggles
  • Filter mask
  • High-pressure washer
  1. Start with a coarse silicon carbide sandpaper and conclude with a finer (80, 120, 180, 220) sandpaper.
  2. Rub surface in a circular motion, smoothing edges of the old paint job.
  3. Remove dust occasionally by vacuuming or striking the sandpaper on a hard surface. Replace sandpaper when it becomes encrusted.
  4. Fold sandpaper occasionally for a new sanding edge.
  5. Vacuum up dust.