Sanding Techniques and Tips
Photo copyright 2010 Lesley Shepherd, Licensed to About.com Inc.
Sanding is a technique for removing blade marks, not for fitting pieces! Learn how to cut accurately, rather than relying on sanding to make something fit. Start with a grade of sandpaper which will not ruin the existing finish.
- Always use a dust mask or a respirator.
- Mount sandpaper to a wooden block with glue or spray glue, to help keep sanded edges sharp. Make sanding sticks from toothpicks, craft sticks or small pieces of wood.
- Always sand wood in the direction of the wood grain. One stroke against the grain requires 20 strokes with the grain to correct.
- For small pieces it is better to rub the piece on the sanding block to prevent over sanding.
- Vacuum or dust wooden pieces with a soft paint brush after each sanding grade, and follow this initial dust removal with a tack cloth to remove very fine particles of dust. This avoids loading the new sandpaper with particles from the larger grit used earlier.
- Use a tack cloth to remove fine dust before the final finish.
Wood Sandpapers and Methods - Grits From 80 – 240
Sandpaper is used on wood to remove milling marks or tool marks. It should not be used to square edges. Learn to make accurate cuts with properly aligned knives, drills and files.Use a mitre box and a razor saw for accurate cuts on wood strips. For wood miniatures, garnet or aluminum oxide sandpapers are most useful. Garnet paper dulls too quickly to be used on metals. Sand with progressively finer grits to remove grooves made with the previous sandpaper. For very coarse marks start with a 80 – 100 grit paper. For pieces without large marks, start with 120 to 180 grit (medium) and finish with 220 to 240 grit (fine). For stained pieces, using finer sandpaper will restrict the amount of stain that penetrates the wood. Stop sanding at 180 grit before staining, giving it a final sand after the stain dries.Sandpapers and Polishes for Metals
Aluminum oxide papers (also used on wood) can be used on metals in finer grits.
Silicon carbide sandpaper is useful for sanding paint finishes and for finishing metal. Most silicone carbide papers are 'waterproof', designed for wet or dry sanding.
Crocus cloth is 600 - 1200 grit jeweller's rouge on a flexible cloth backing. it is useful for polish sanding metals and plastics, and removing small burs from fine needles and other tools. It will leave behind a slight coating, use with caution on some finishes.
Jeweller's Tripoli and Rouge are metal polishes which have small particles in a wax or clay suspension. They are used on a soft cloth or polishing bit to polish irregular areas of metal miniatures, jewellery and polymer clay.
Plastic Surfaces
Photo copyright 2009 Lesley Shepherd, Licensed to About.com Inc.
Most finer grade silicone carbide papers and crocus cloth can also be used to sand and polish both plastics and metals.
To remove or prevent scratches in plastic it is very important to sand with progressively finer grits. Special kits for sanding plastics or paint finishes to a perfect shine, or clear finish are available, most often from auto body shops.
Review of Micro Mesh Sanding Pads for Paint, Plastic and Metal Surfaces
Painted Surfaces
Use the same types of sandpapers as for plastics, depending on the sheen of the finish you wish to achieve and the relative detail of the piece your are sanding.
Fine 000 steel wool is good for removing brush marks from paint coats on scale building components. Silicone carbide papers or micro abrasives and micro abrasive pads (see plastics) can be used to create gloss finishes, even on flat paint coats. Automotive 'cut polish' can also be used to put a fine gloss on scratched paint coats on painted or metal surfaces, residue from these polishes will need to be removed before coats other than wax are used.
Steel Wool For a Fine Finish
Photo copyright 2010 Lesley Shepherd, Licensed to About.com Inc.
Finer grades of steel wool can be used for metal and wood miniatures. Steel wool cuts very quickly so caution must be taken when using it or you can easily go right through a finish. Care must also be taken to clean away all bits of steel wool which may be left on a finish as it will rust.
00 grade steel wool is generally used for metal polishing, 000 will flatten paint and varnished surfaces before the final coat, 0000 is used for final finish sanding of clear coated wood finishes (varnish and shellac coatings),cutting the sheen on a final gloss finish to give more realistic furniture polish finish to miniatures.
Special Use Polishing Materials
Photo copyright 2010 Lesley Shepherd, Licensed to About.com Inc.
Knife Honing - Micro abrasives, very fine silicone and carbide grit papers, are available for polishing car bodies and sharpening and honing tool blades. The two shown here are mylar backed papers from 3M in grits of 5 micron and 0.5 micron. (equivalent roughly to 2500x and 9000x). These papers are available online from Lee Valley. The micro abrasives will also put a mirror finish on other materials, but as they have a plastic backing sheet, they are not as easily manipulated into fine details as are cut polishes or metal polishes on a soft cloth.
Rottenstone - is the powdered, non additive version of tripoli, used as a jewellers polish. It is usually mixed with water or oil, and applied as a fine paste to polish brass and finish varnish.
Final Finish Sanding and Polishing
All silicone carbide papers and crocus cloths used for fine final polishing of metals or sanding high gloss and semi gloss painted surfaces can be used on clear coat wood finishes. Silicone carbide papers in higher grades will give a very fine final finish to miniature furniture.
To sand a final paint or varnish or shellac finish to a perfect sheen, scaled to an antique wood finish, use rotten stone powder (see above) and a pure (low water containing) rubbing alcohol with a soft cloth, or use 0000 steel wool before applying a thin coat of paste wax.
For metal miniatures you may wish to use a polish containing a tarnish resistant finish, or apply a clear sealant over the metal miniature.
