STRIPPING WOOD

Wood has a natural beauty, but it’s often a beauty concealed by layers and layers of paint. Doors, window frames, even skirting boards and architraves can all become attractive features in themselves when stripped back to reveal the wood. Even if you prefer to repaint, using the right techniques to strip off the old will give the best possible surface on which to work.

S tripping wood of old paint or layers of ancient varnish isn’t the easiest of jobs. It’s usually only done because you’re after a natural finish, or because the painted surface has degenerated to such an extent that further coats of paint simply can’t produce a smooth finish. Either way. Once wood has been stripped back to its natural state, it then has to be sealed again – to protect it from moisture which can cause cracking, warping and ultimately decay. Both varnishes and paints act as sealants, giving a durable finish. But which one you choose might depend on the wood itself – and you won’t know what that’s like until you’ve stripped it. If you’re unsure of its quality, it’s advisable to strip a test area first.

Some of the timber used in houses is of a grade that was never intended for a clear finish – large ugly knots, cracks, splits or even an unattractive grain are some of the signs. In cases like this it is probably better to treat the problems (eg. Applying ‘knotting’ – a special liquid sealer – to make the knots tight and prevent them ‘bleeding’, filling cracks and splits to give a flush surface) and then paint to seal.

However, is useful for getting small areas smooth after paint has been removed by other methods.

One such attachment is a ‘disc sander’ and is quite tricky to use effectively without scoring the wood surface. Hold it at a slight angle to the wood and present only half the disc to the surface. Work in short bursts and keep the disc moving over the surface – if it stays too long in one place it can damage the wood.

A ‘drum sander’ attachment has a belt of abrasive paper stuck round the edge of a cylinder of foam, and if used along the grain only is rather easier to handle than a disc

If you are set on having the wood on show and don’t want to paint it – because it wouldn’t fit in with a colour scheme or make the feature you want – you can give it a better appearance with stain or coloured varnish.

Stripping with abrasives

For dry stripping there are several different kinds of powered sanders available, all of which use abrasive papers of some kind to strip the surface off wood. On large areas such as floors it is best to use a purpose-made power sander which you can hire. A drill with a sanding attachment, sander. Whichever type is chosen, a fine grade abrasive should be used for finishing stripped wood.

Orbital sanders (which are also known as finishing sanders) usually come as self-powered tools – although attachments are available for some drills. These have a much milder action and as long as the spread of wood isn’t interrupted by mouldings they smooth well and are useful for rubbing down between coats. These sanders are rectangular and should be moved over the surface in line with the grain.

For sanding by hand – hard work, but much better for finishing – there are many grades of glasspaper from the coarse to the very fine. On flat surfaces it’s best to wrap the paper round a small block of wood. As an alternative to glasspaper, there’s also steel wool, which is most useful when you’re trying to smooth down an intricate moulding. Always sand backwards and forwards not across it. Scratches across the grain will always be highlighted by a clear finish. To remove remaining bits of paint use medium grade glasspaper; for finishing, a fine grade is better. Renew the glasspaper frequently as the paint will clog the surface, although a useful tip is to try cleaning clogged paper with a wire brush. It’ll work once or twice, but after that the abrasive surface is usually lost. Alternatively pull the sheet backwards and forwards, abrasive side uppermost, over a table edge to dislodge paint particles.

A useful tool for cleaning paint from corners and mouldings is a hand scraper with replaceable blades. These ‘hook’ scrapers are also used for ‘smoothing’ and often need two-hands – they slightly raise the surface of a clear run of wood, giving an attractive finish under a clear seal. Use with the grain.

Heat stripping

Heat stripping is the quickest way to remove paint or varnish, but it needs a lot of expertise if you are to avoid charring the wood. So it is best reserved for stripping out of doors where a less-than-perfect surface will be less noticeable. A gas blow-torch is used along with metal scrapers to lift the finish off the wood while it’s still warm. Blowtorches with gas canister attachments are light to use and a flame spreader nozzle makes the job easier (it can be bought separately). Where there’s no glass, it’s a two-handed jeration. Light the blow-torch and hold it a little way from the surface. Move it back and forth, going nearer and withdrawing, till the paint starts to wrinkle and blister. Now begin to scrape – be careful where you point the flame at this stage or you may damage other surfaces. As soon as the paint is hard to move return the flame to the area. Wear gloves to save your hands from being burnt by the falling paint, and cover areas below where you are working with a sheet of non-flammable material to catch th-e scrapings. In awkward areas, especially overhead, you should wear protective goggles for safety’s sake.

Chemical stripping

Chemical strippers are probably the easiest way to strip wood. Available in liquid, gel and paste forms, their methods of application and removal vary, so always remember to read the manufacturer’s instructions before you begin. Though all of them will remove paint and varnish, if you are dealing with a large area of wood they can work out to be very expensive – they’re also very messy.

Liquid and gel strippers, decanted if necessary into a more convenient-sized container (read the instructions as to whether it can be heavy gauge plastic or should be glass or metal), are stippled onto the surface with a brush and left till the paint bubbles before scraping. Usually these strippers will work through only 1 layer of paint at a time so several applications can be necessary. If stripping a chair or table, stand the legs in old paint cans or jam jars so that any stripper which runs down the legs can be recycled. Artists brushes rather than paint brushes are useful when applying these strippers to mouldings or beading in windows and No 2 steel wool is useful for removing it.

After liquids or gels have been used, the surface must be cleaned down with white spirit or water (it depends on the stripper used) to remove any trace of chemical and must be left till completely dry before any stain or seal is applied.

Pastes are mostly water soluble and manufacturers stress important conditions for using them safely (eg. Not in direct sun, in well ventilated rooms, the wearing of protective gloves, etc). Bought in tubs ready-mixed or in powder form to be made up, they are spread in thick (3-6mm) layers over the wood which must then be covered with strips of polythene (good way of using up plastic carrier bags) or a special ‘blanket’ (supplied with the tub) which adheres – when you press it – to the paste. They have to be left for between 2 and 8 hours after which the paste can be scrubbed off (with a firm brush) or washed down. Frequent changes of water are needed; follow manufacturer’s advice about additives (eg, vinegar). Pastes are particularly effective with extraordinarily stubborn paint or varnish in very awkward places (eg. Windows, bannisters etc); or where using a scraper might damage old wood. Some pastes are unsuitable for certain types of wood and can stain it – so read instructions carefully. Washing down should not be done, for example, with valuable furniture for this can raise the grain of the wood.

Bleaching

If the wood is discoloured once stripped (either from the stripper used or from some other source) you can try and achieve an overall colour with bleach – the household type, used diluted 1:3 with water to begin with and more concentrated if necessary, or better still a proprietary wood bleach.

Clean the surface of the stripped wood with paint thinner and steel wool and leave for 15 minutes to dry. Cover areas you don’t want bleached with polythene, then brush bleach on generously. Work it into the wood using medium steel wool.

Leave for 2-4 minutes, then wipe off with rags. Leave to dry (up to 5 hours) before sanding after which you can finish the surface as desired.

There are several different ways of altering the look of stripped wood.

– are based on water, white spirit, alcohol, lacquer thinner or oil. Named after the wood whose colour they resemble, these penetrate the wood permanently. To give an even staining, the trick is to apply several thin coats — work from top to bottom on vertical surfaces to prevent drips and overlap marks. Use a pad (not a brush) made with cotton wool wrapped in a lint-free cloth and work backwards and forwards along the grain. When completely dry, seal with a clear varnish that is compatible with the stain. If applying more than one sealing coat, rub down the surface each time with fine glasspaper.

– both seal and ‘stain’ the wood surface and are removeable. They are also named after natural timber and are applied like ordinary clear varnish to sanded-smooth wood. You just go on applying the coats till you get the colour you want — rubbing down between each. Varnishes are oil (interior and exterior grades), spirit (not suitable for outdoors) or polyurethane based. Polyurethane varnishes can also be non-wood colours (such as red and green) and are especially useful if you want inexpensive wooden furniture to fit in with a colour scheme.

When using varnishes remember:

Never use a cellulose filler for it will always remain as a white mark. Choose a wood filler of similar colour to the stripped wood.

They have to be applied to perfectly smooth surfaces with all dust, grit and paint particles removed — wipe down with white spirit first, then leave to dry.

Don’t attempt to apply them in dusty or windy conditions — the merest speck will spoil the finish and to be truly effective, stripped and sealed wood has to be beautifully smooth to the touch. A spray will give a more even finish than a brush.

– both colour and seal.

They are particularly suited to wood exposed to the elements (eg, outside doors and window sills) or wood that isn’t in very good condition. Choose from a range of natural timber colours and apply several coats to give the wood ‘depth’.

WHAT TO USE WHERE

For large flat areas such as flush doors and skirting boards, use a

– blow-torch for speedy stripping if you’re going to repaint it

– powered sander if you’re going to varnish.

For intricate mouldings and awkward areas such as staircases, panelled doors and window frames, use.

– a blow-torch and a shavehook if you’re repainting

– chemical strippers if varnishing (remember they’re relatively expensive).

For fine finishing use.

– glasspaper and sanding block or an orbital (powered) sander.

Caustic soda

This is used for ‘immersion’ stripping of doors and other fairly durable pieces of furniture. If you have a suitable old galvanised iron tub or water tank, remember to put the water in first then add the crystals. BUT remember that.

– caustic soda is a powerful chemical: handle with care

– immersion stripping can loosen old joints and peel off veneers

– you must wash down the wood with water after stripping

– you’ll have to finish the wood with glasspaper or a powered sander.

DOS AND DON’TS.

– DO leave a freshly lit blow-torch to stand for a few minutes or it may flare dangerously when moved.

– DO wear gloves if you’re using a blow torch OR chemical strippers

– DO wash splashes of chemical strippers off your skin immediately

– DON’T use a blow-torch to strip wood you intend to varnish – scorch marks are almost impossible to avoid

– DON’T work in a very confined space with chemical strippers.

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