Sanding Tips: Smoothing Surfaces by Hand and Power Tool
When sanding wood, work only with the wood grain – never across it. Scratches across the grain are very hard to get rid of, and finishes such as varnish show them up.
Do not use abrasives to remove paint and varnish. The heat generated by friction melts the pain, which clogs the abrasive and soon makes it useless. Strip a surface before sanding..
Types of abrasive include:
Glass paper (or sand paper)
Use it dry for woodwork that does not need to be very smooth, such as when rubbing down before painting. This is the cheapest abrasive.
Garnet paper
A harder, better quality abrasive, garnet is used for the fine finishing of furniture that is to be sealed, varnished or polished. Use it dry.
Emery paper or cloth
Use them wet or dry according to the maker’s instructions, for cleaning and finishing metal. Emery is tough but tends to clog easily. Use cloth on curved surfaces – tear off a strip and hold an end in each hand, working it back and forth.
Silicon-carbide paper
Often called wet-and-dry, this paper can be used either way. Use it wet for removing the glaze from paint before repainting – the water acts as a lubricant and also keeps down paint dust, which may contain lead.
Tungsten-carbide disc, block or file
A casting of very tough material is brazed onto a metal backing to make these abrasive tools, which are available for coarse and fine grades. Use for coarse sanding or for removing paint.
Sanding pads
Grades by Os – the Os, the finer the wool. Use fine grades, with white spirit as a lubricant, for taking the gloss off sealers and varnishes before re-coating. Very fine grades are also useful for removing scuff marks from vinyl floor coverings. Never use coarse grades on woodwork.
Sanding by hand
For smoothing curved and shaped areas use an abrasive sheet folded and shaped in the hand. For smoothing flat surfaces use an abrasive with self adhesive backing and mount it on a rubber faced hand sanding block.
When rubbing down old paint and varnish for repainting, use a flexible pad sander lubricated with clean water. For breaking up the surface of painted over wall coverings, use a coarse grade tungsten-carbide sanding block or file.
Power sanding
Be extra careful when power sanding – it is easy to take off too much material. Use coarse abrasive for shaping and rounding, and fine ones for smooth finishing.
Power sanding is done either with an attachment to a power drill or with a tool specially made for sanding. Popular power drill attachments are a disc sander, a drum sander and a flap wheel. A disc sander is a flexible backing pad that holds a removable abrasive disc by either a screw and washer or self adhesion. Keep it for rough work, as the disc always cuts across the grain of the wood, leaving marks which are hard to remove. A drum sander is a foam drum with a band of renewable abrasive fixed round it. Various grades of abrasive band are available.
A flap wheel consists of a spindle and core with numerous flaps of abrasive fitted round it. As the abrasive wears, it disintegrates, exposing new material, until the flaps are completely worn away. Various grades are available. Use it for cleaning and smoothing wood such as windowsills or furniture, or metal.
An orbital sander is a available as either a drill attachment or (preferably) a separate too. It has a very fine orbital movement that removes only a little material. Use it for fine finishing work on flat surfaces such as a table top.
A belt sander is a semi- professional tool that has a belt of abrasive rotated at fairly high speed. Use it for final smoothing after planing, for leveling floorboards, or for getting into corners where a floor sander cannot reach.
A floor sander is an industrial sanding machine that can be hired. Abrasive belts of various grades are supplied. Start with coarse for leveling and progress to fine for finishing. Use it for cleaning or stripping timber floors and leveling large areas of uneven floorboards.
