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Woodcarving for Beginners

Finishing Wood
Index

Overview

Enhancing the beauty of timber with polish, lacquer, varnish, oil, wax, or gold or silver leaf is one of the more pleasurable aspects of woodworking. Similarly, a great deal of satisfaction can be obtained from staining or colouring wood. There is also the practical aspect of protecting the wood to keep it free from marks, and also to avoid the penetration of moisture which might cause movement of the finished work, or worse still - splitting or cracking.

Consideration should be given to how a piece will be used or viewed, whether there is significant grain that could be enhanced, as well as how it will be subject to wear, when determining which colour and finish to apply. Texture and grain will also determine the type of finish and not least, what preparatory work may be needed, whether a grain filler will be needed or not. Finally, always remember to work in well lighted and ventilated conditions whenever you are applying finishes. Light is needed to match and co-ordinate colour, and ventilation to get rid of unwanted fumes etc.
Index


Preparation & Sanding

Sandpaper Grades
Very Coarse 50 1
  60 1/2
Coarse 80 0
  100 2/0
Medium 120 3/0
  150 4/0
  180 5/0
Fine 220 6/0
  240 7/0
  280 8/0
Very Fine 320 9/0
  360  
  400  
  500  
  600  
Abrasive papers: A variety of abrasive materials glued to paper backing sheets are used to smooth timber, collectively known as sandpaper.

Glasspaper: is pale yellow, wears quickly and although not really suitable for fine woodwork, is a cheap option for sanding softwoods.

Garnet paper: is made from a reddish-brown natural mineral that forms hard particles with sharp cutting edges, good for softwoods and hardwoods.

Aluminium-oxide paper: is even harder than garnet paper and is used widely as an abrasive for power tools, and especially good for sanding dense hardwoods.

Silicon-carbide paper: is dark grey to black and used mainly for finishing metals, or with water as a lubricant, for smoothing paintwork between coats. Often refered to as 'wet and dry' paper. Can be used dry for sanding hardwoods. A pale grey silicon carbide paper dusted with zinc oxide powder that acts as a dry lubricant is preferable for rubbing down French Polish between coats.

Cabinet Scraper: This should be used to clean off large flat areas before the work of sanding begins. Work in the direction of the grain, taking care not to scratch the timber with the edges of the scraper. After an initial clean to remove imperfections, wipe down with a warm, moist rag. Allow to dry, and scrape off again to remove the raised grain.

Hand sanding: Tear a sheet of sandpaper into four parts, and using one part, wrap it round a cork block for sanding smooth surfaces, working in the direction of the grain. Start off with a coarse paper, and use successively finer grades to remove the scratches of earlier papers.

When the surface appears to be as smooth as desired, damp down with a warm, moist rag to raise the grain, allow to dry, and sand off again with a finer paper.

Take care not to round over sharp corners inadvertently. If you want to remove the arris, the sharp edge, sand a chamfer deliberately using the block. Use a shaped block for sanding mouldings.

Use fingertips only, and not the block, for smoothing rounded or curved surfaces, for very light sanding, and especially when using very fine paper between polish coats. Sanding between coats is called de-nibbing, and the papering smoothes off the raised grain or polish nibs that arise as work is coated.

When the paper becomes clogged, tap it out against the workbench to clear it. Finally, remove the wood dust with a dry cloth or brush.

Sandpaper should be stored in a dry environment at normal room temperature. If it should get damp, it will be useless, but may be revived by drying out for a short time in an oven or microwave. This is not to be recommended, since it can catch fire, so the process must be watched directly and not left on its own.
Index


Filling holes and cracks

Whether you have a less than perfect piece of wood, or whether you are restoring old work that has cracks or knot holes, stopping should normally be carried out before staining and polishing, so that the stopper can be masked and coloured along with your final finishes. There are various materials available and some of them are descibed below.

Knotting - Mainly softwwod will sometimes exhibit the bleeding of resin, especially from knots, and therefore it will be necessary to apply 'knotting' to the affected area, otherwise the resin will bleed through paint and other finishes and leave a stain. Knotting is a shellac based sealer.

Stopper - A proprietary stopper is a stiff paste made to fill small holes and cracks, and while available in a variety of colours, you will only be able to get an approximate match. To better match, you can obtain powder colours from a commercial polish suppliers that you can add to white filler before use, but try it on waste wood before hand. Apply and sand off when dry with a fine garnet paper.

Cellulose filler - Only useful where an opaque or painted finish is desired. Available in powder to which you make up a paste with water, or as a ready made paste.

Shellac sticks - Sticks of solidified shellac are ideal for repairing a crack or small knot holes before applying any type of finish. Made in several colours. You can use the tip of an electric soldering iron to melt the shellac, allowing it to drip into the crack. While still soft, press into the crack with a putty knife or chisel. Cut off the surplus with the chisel when cold, then sand flat with a fine garnet paper.

Wax sticks - Best used on finished work since most finishes will not take over wax. Break off a small amount of the wax and warm by working in the palm of the hand, then using a warmed knife blade or similar, press the wax into the crack, then clean off flush with the surface.

Removing patches of Glue - When using glue for repairs, or joints, always wash off excess glue with a warm, damp cloth. If you let the glue set in the grain of the wood, it will prevent the penetration of stain, and will show a pale patch on the finished job. If glue has gone hard, then use a cabinet scraper to remove.

Tool Marks - If have have accidentally dented a workpiece, raise the dent out of the wood with hot water. Soak the surface that has been dented using a rag dampened with boiling water, mind your hands, and apply to the affected area for a few minutes. This should do the trick. If not, repeat using a hot iron over the damp cloth. The fibres of the wood in the local area will swell, and lift the dent. Allow to dry, then sand off flush.
Index


Bleaching

Many timbers, such as mahogany and walnut, will lighten with age, and in order to match older work, it may be necessary to bleach the workpiece, before polishing. The usual process is by the application of a two part hydrogen peroxide bleach available from commercial polishing suppliers.

The bleach comes as a two part pack. After preparation, well shake the bottles and apply the part 1 solution to the wood, with a white fibre or nylon brush fairly liberally. Then, after washing out the brush, or using a different brush, apply the part two solution, making sure the surface is well wetted. Leave for about twenty four hours to dry, and sand off the raised grain with a fine garnet paper. If the colour is still not light enough, repeat the process.

Warnings: Always wear rubber gloves for this job since the chemicals are toxic, and carry out in a well ventilated area wearing a face mask. Do not contaminated the one solution with the other, otherwise they will be useless if needed again. Wash out all brushes well after use. If you are tempted to use an ordinary paint brush for this job, it will be bleached along with the workpiece, and may contaminate paintwork if it is later used for this purpose with a chemical reaction. Wear an apron or protective clothing.
Index


Staining

There are four principal types of stain that you need to be aware of and which are available commercially.
  1. Water Stains
  2. Spirit Stains
  3. Oil Stains
  4. Naptha Stains
You can also purchase colours and dyes and chemicals to add to various solvents to make up your own, but this course does not cover the latter at this stage.

The first three types of stain are easily obtainable from Do-It-Yourself stores, penetrate timber well and provide a good depth of stain over which you can polish. The main drawback of these types of stain is that if you have to do any later repairs to the subject due to abrasion, scratches, or even if you want to make some small alteration, you will find that like water colour painting, a fresh application of stain to the affected area will tend to leave a ring of darker stain around the new wood. Naptha stain however overcomes this problem, and allows subsequent stain to be applied without leaving the tell tale ring. The colour is absolute, and remains the same however many overlapping coats are applied.

Naptha Stain can be recommended for beginners, and is used commercially by many polishers. You will probably have to look for a specialist drysalters or specialist polish supplies company, as it is not so readily available. Colour penetration is not so good as the other types of stain, but for woodcarvers, this is no great drawback.

After the wood has beed sanded and cleaned, apply a coat of stain using a nap free cloth, or paint brush in difficult corners, and to get an even stain colour, immediately wipe off before dry with another cloth. If the stain is too dark, and it is a good idea to try it on a scrap piece of wood first, thin it out with the appropriate solvent, white spirit in the case of naptha stain. Allow about an hour to dry, before applying polish. If you want to get highlights in the work, then you may lightly sand the raised portion of the carved work with a hand held 200 grit garnet paper or finer after the stain is dry, otherwise do not sand after applying stain until the work is polished. You may lighten the stain colour, by the addition of white spirit to the stain before application. You are now ready for polishing.
Index


French Polishing

There are four main types of French Polish that you will commonly come across, and this finish is applied to internal work that will not be exposed to outside or wet conditions, although the odd water splash can be wiped off with little harm. Mostly used for interior decorative work such a wood carvings, and furniture that will not be subject to hard wear. French Polish is made by dissolving shellac flakes in methylated spirits, although it is much more convenient to purchase it ready made.

Sanding Sealer is a type of French Polish that is used on absorbent woods and is applied in such cases as a first coat in order to seal the pores in the wood before applying a White or Button Polish second coat. As its name implies, it is a sealer coat.

White Polish and Button Polish you will be able to obtain from most Do-It-Yourself stores, while Clear, will usually only be obtainable from a commercial polishing supplies company.

Clear Polish, or Transparent Polish as it is sometimes known, is clear in colour, and has the natural wax removed from the shellac base, and only tends to be used on pale woods such as birch, or sycamore, and which would tend to yellow slightly with the application of either of the other types.

White Polish is a creamy yellow in colour and is probably used as much a Button Polish, which is a dark brown colour. The principle difference on application, is that Button Polish will add a slight warmth of colour to the finished work. The best option as always with finishes, is to try some on a scrap piece first until you get more confidence with the materials. Polishing Mop

BRUSH POLISHING - The traditional polishing mop, illustrated, is made from fine squirrel hair and is the ideal applicator for French Polish as used commercially. Purchased from a commercial polishing supplies company, the professional will add a pin at the side as shown in the illustration, to enable the brush to be held on the side of the polish jar when not in use, thus preventing brush curl and a consequent spoiling of the brush tip. If you cannot obtain such a brush, then use a fine, soft haired paint brush.

If the polish brush is being used over a period of days, then the best way to store the brush, is to wipe the surplus polish from the brush after use, making sure that the brush retains the proper shape, then laying horizontally on the top of the jar to dry. This stores the brush quite happily, and when required for re-use, simply hang the brush back on the side of the jar in the polish to soften up again for about half an hour, and it will be perfectly restored for use. If you have finished work for a longer period of time, wash the brush out in methylated spirits, and store laid flat so as not to harm the brush shape.

French Polishing in its simplest form requires the use of between two and three coats of polish to the prepared wood, cutting down with fine silicon-carbide paper, 0000 grade wire wool, or fine 240 grit garnet paper between coats in a process called de-nibbing. De-nibbing simply means the removal of polish nibs that collect from raised grain and sometimes by dust that falls on the tacky work from the workplace. Don't flood the work with polish and spread it out well using quick strokes of the brush both across and down grain. The successive coats of polish will fill the grain and the cutting down will smooth the tops of the grain ridges so that a smooth surface is obtained. After the last coat is applied and cut down, apply a wax polish and buff off. The last cutting down operation can be carried out with 0000 grade wire wool dipped in wax polish. You are finished !


USING A RUBBER - Traditional French Polishing is carried out using a rubber, which requires a little more skill to get right. The polish is applied, thin layer upon thin layer, using a ball of cotton wool in a white linen rag to make a soft pad, which is the 'Rubber'.

Polishing Rubber To make the rubber, you start with a piece of nap free material about 300mm square, add a handful of wadding, or cotton wool and wrap the cloth round it to form a ball making sure that it is of a size that can be held easily in the palm of the hand, and the underside surface which will be in contact with the work surface, is wrinkle free. The rubber is 'charged' with polish by opening the rag out, pouring some French Polish into the wadding so that it is moist while not saturated. Re-wrap the rubber, squeeze gently to distribute the polish through it, and with the tip of your finger, add a drop of linseed oil to the sole to act as a lubricant.

To apply the polish, first make overlapping strokes with the rubber, gradually covering the whole panel. Then go over the surface again using a figure of eight pattern, varying the strokes to get an even coverage. Finish off parallel with the grain. Little pressure should be needed on the rubber, but always keep it on the move. If you stop with the rubber in contact with the surface, it will stick and scar the surface, in which case you must let the work harden off, then sand the scarred area with silicon carbide paper to remove the blemish and then start again.

Once the first application is dry, which will take about half an hour, repeat the process four or five times. Allow to harden overnight, cut down with silicon carbide paper, and repeat the process another four or five times. Judge for yourself when you think you have built up a sufficient body of polish to give the required depth of colour, but you will probably need something like 10 to 20 coats to give a high gloss finish. Finally, wax and buff off. If you don't want a high gloss finish, you can give the work a satin finish by rubbing down with wire wool and wax as described above, stroking the wire wool with the grain, and again buff off.
Index


Gold & Silver Leaf Work

There will be more information coming about this subject, but a number of people have asked me where to get gold leaf supplies, and for people in the South Staffordshire and Birmingham area, a very helpful source of materials is John Meadows, of W Habberley Meadows Ltd, 5 Saxon Way, Chelmsley Wood, Birmingham B37 5AY. Tel: 0121 770 0103.

The usual material for woodcarvers is English Gold Leaf - transfer gold, and the stock I am working from is 23¼ ct. medium deep, seconds, purchased as a book of 25 and each page has on it a square of 80mm leaf. You will also want some 24 hour gold size to go with it.

To prepare the workpiece or letters, the work surface needs to be as smooth as possible, because gold leaf is very thin, and has no gap filling properties. If you have used a close grain timber, it may be sufficient to provide a couple of coats of french polish to seal the grain. If a coarser grain material has been used, then the grain will have to be filled first, a sealer of french polish to finish, then proceed as before.

Apply the gold size to the area to be covered, and 24 hours later it will have achieved the right 'tack' to apply the gold leaf. If you are only doing a small area and don't want to get all the best kit for the job, rub the gold leaf onto the workpiece with the smooth side of a 2b pencil lead. When done, you may find odd gaps which you will need to fill with a second application.

Ring, E-Mail, or Fax us now, and find out a little more.

Visit us by E-Mail: woodcarving@ldb.co.uk

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Last updated: April 4th, 2000.
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