Furniture Finishing Tips from the Trade

Scumbles, sometimes called graining colours, are generally used for hand-graining cheap woods to make them look expensive. Specially formulated to ‘stay put’ wherever they are applied, they do not flow out like orthodox oil paint-so enabling various designs to be made with a dry brush, a piece of cloth or a graining tool.

Scumbles may be bought in various colours from specialist stockists of decorators’ materials.

You also need cellulose paint. As this dries quickly, do not brush it out. Just lay it on the surface with broad sweeps of a brush; you can also buy it in aerosol containers and spray it on. It can be thinned and applied with a spray gun.

Imitation gold leaf

A finish nearly approaching that of gold leaf is achieved by applying a sticky varnish, leaving it until it just starts to dry. Next, rub in fine bronze dust, using a lintless cloth, in a circular polishing motion. Bronze dust may be obtained from colour merchants and artists’ sundries shops. This is used for picture frames, shelf edging and enriching reliefs.

Antique effect on picture frames

This process may be employed to make a new picture frame look old. After varnishing the surface, rub in bronze dust and leave for a few days to harden; paint on a dark-coloured scumble and, while this is still wet, rub off the highlights with a soft, lintless cloth – so leaving brightly burnished reliefs and dirty-look valleys.

An ordinary oil paint would also be suitable, provided it were well thinned and applied sparingly, so that the bronze underlay in the interstices slightly ‘grins through’.

Crackle finish

Achieved by painting with a brush a short, brittle coat over a flexible undercoat-such as a hard, fast-drying oil paint over an ordinary undercoating, to which a little boiled linseed oil has been added to make it softer.

Another way is to apply a light-coloured scumble over a dark ground coat and then scratch on the pattern with a pointed tool. This will take longer, but it will enable you to control the position and extent of the ‘crazing’.

In this case, scumble must be used; paint will flow out to fill the cracks as fast as you make them.

Using a spray gun or aerosol container, you can get a realistic crackle by spraying through plumbers’ tow; this is first teased out and stiffened with glue size.

Another method using glue size is to coat the whole surface thickly with glue-relying upon the contracting property of the drying glue to craze the painted surface. Wash off the glue and then varnish the surface.

Ebonising

Where the substrate is oak, apply an iron-salt solution liberally. Iron salt is sulphate of iron dissolved in water. You can make it yourself by immersing bits of iron in vinegar for several days; or by leaving rusty nails in water for a week.

For other woods, treat the surface with tannic-acid solution which can be made by boiling oak galls, oak bark or scraps of oak in water. When the surface has dried, rub down and polish or varnish. In all cases, the black improves with time.

A good way to ebonise a staircase rail is to apply three or four coats of black cellulose paint, rubbing down between coats with fine abrasive paper. Leave for 48 hours and rub with fine steel wool moistened with soap.

Fumed oak

This is only a suitable treatment for small objects. Place the article on a grid over a pool of ammonia in a sealed box. Use care when opening the box as ammonia fumes are unpleasant.

If you wish to darken an oak fence, add oil-soluble nigrosine powder in a small quantity of naptha to creosote, and brush on. Another way, but not quite so good, is to add carbon black in white spirit to the timber.

Application should be made in warm weather when the timber is dry and its pores enlarged so that there will be adequate penetration.

Blackening steel

Clean with fine steel wool and household abrasive cleansing powder. Then mix the following, by volume, in this order: 125 parts of water, 15 parts of nitric acid (always add acid to water; never water to acid), 30 parts of alcohol, eight parts of copper sulphate. Apply the mixture and polish when dry.

Antique-leather effect

Applied over a rigid surface. Use a dark brown scumble over gold paint. If oil scumble is used, give a buffer coat of clear lacquer first.

10. November 2011 by admin
Categories: Featured, Handyman Tips | Tags: , , , , , , , , , | Comments Off on Furniture Finishing Tips from the Trade

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