Wood finishing has been quite a journey for me.
The pursuit of an amazing finish has been ongoing ever since I started seriously working with wood some 25 years ago.
A finish is really just a protective coating right? Well, technically yes, but it’s more than that..
The finish is the surface that people touch, the platform that light bounces off and the window that reveals the colour and character of that amazing wood that toupee used for the piece you’ve been slogging your guts out over the last 4 weeks solid.
So, is the finish important? You bet it is!
What then are we looking for in a finish? Well what I’m looking for is a product that not only looks and feels amazing, but gets better with age, revealing the way the piece has been used and lived with over its life.
What this means is that the original finish stays with the piece throughout its long life as it is used and passed on from one generation to the next. As the surfaces are worn, each successive coat needs to be able to bond to the last and build to form a beautiful patina.
Last year we shut down our spray booth and have moved to only natural finishes for our wood products. The spray applied membrane finishes I had grown up with just wouldn’t last – we were finding that after 10 or so years the coating had lost its original clarity and, if damaged couldn’t be spot repaired. I don’t know if you’ve ever sanded a finish back to raw wood and started again but its certainly not my idea of a good time!
The other thing I disliked about spray finishes was the chemicals – they smell so bad and are seriously damaging to your health and the environment.
Currently we have 3 main finishes that use regularly:
- Osmo Polyx-oil
- Pure Tung Oil
Ill also explain a bit about Paste wax at the end as an aftercare product
All of these are natural products, food safe, and make excellent finishes that will last. Where to use each finish will depend on the desired appearance of an item and the degree of protection that will be required.
Osmo, from Germany, has developed wood finishes that are perfectly geared to and preserve the special properties of wood. Natural Oils (sunflower, soybean and thistle) penetrate wood and protect it from inside. Waxes (carnauba and candelilla) form an elastic, breathable surface that protects wood from outside.
Osmo Polyx®-Oil was developed as a floor finish and is also very popular for furniture finishing. It is especially good if you like the look and feel of natural wood rather than and plastic coating.
This Hardwax Oil surface is extremely tough and hard-wearing. It is water-repellent and dirt-resistant. The finish is highly resistant against water and dirt and other liquids used around the house such as wine, beer, cola, coffee, tea, fruit juices, milk and water etc. when dry according to DIN 68861 1C (German Industrial Norm).
It is also resistant to perspiration and saliva, food-safe and even suitable for children‘s toys.
Wooden surfaces correctly treated with Osmo Polyx®-Oil will last for generations. The protective microporous finish allows the wood to perform well in conditions of high humidity by allowing the wood to breathe so makes an excellent finish in the kitchen or bathroom.
The finish repels moisture and dirt but should any dirt or damage occur, it is easy to clean and repair.
Application is super easy – prepare the wood by sanding up to 180 grit and ensure the surface is clean. Apply the first coat thinly and then give it a second thin coat after 8 hours. Interior use only and available in matt, semi matt, satin and gloss.
Damp Cleaning: For frequent cleaning, we recommend using Osmo Spray Cleaner, which is a pre mixed solution in a ready to use 500ml trigger pack or Osmo Wash and Care concentrate, which will need to be diluted in water. The solution contains soaps based on natural plant oils. The ingredients are water soluble and prevent streaking and layer build up. Especially mild on skin, the solution is biodegradable, and is free from dyes, solvents and emissions. The surface remains food safe. Use as often as required.
Avoid using regular household or harsh chemical detergents, as these are designed to dissolve grease and oil, and over time, will break down the Osmo finished surface and leave a container shaped ring.
DO NOT leave hand wash soap dispensers on your Osmo finished surface. The harsh chemicals will break down the Osmo surface.
For tough stains, use of Osmo Liquid Wax Cleaner
INTENSIVE CLEANING AND REFRESHING
From time to time, your wooden surface needs to be refreshed. After continual usage or incorrect maintenance can dull the surface.
Refreshing is normally first needed after about a month in high use areas such as floors or kitchen benchtops.
In most cases, the use of Osmo Liquid Wax Cleaner will be all that is required. Use it sparingly – apply an even, thin coat over the whole area, and then buff the timber
If the timber has a stubborn stain, use a scotchbrite non abrasive white applicator pad to remove. Alternatively, fine grade steel wool could be used. Once the stain has been removed, apply a thin coat of Osmo Liquid Wax Cleaner and buff the timber.
MAINTENANCE AND RE-OILING
Sometimes life can leave marks, even on optimally maintained wooden surfaces. No problem, the protective surface can be renewed at any time, without needing to remove all of the old finish. This is a huge advantage compared to sprayed on membrane finishes.
The process is easy – Clean the surface thoroughly beforehand then apply an extremely thin layer of Osmo Polyx®-Oil and even out with a scotchbrite non abrasive white applicator pad and allow to dry.
Both the Spray Cleaner and Liquid Wax Spray are in ready to use packs. For commercial situations, Osmo Wash and Care concentrate can be diluted with water and used to refill the Spray Cleaner trigger pack. Wash and Care is available in 1 and 5 litre containers. Similarly, the Osmo Liquid Wax Cleaner is available in 500 ml and 1 litre cans of concentrate. The concentrate is applied directly to the timber by cloth straight from the can.
When storing, keep sealed off from air, cool and dry, out of the sun and try to expel any air from the head of the container by laying an oversized square of cling film on the surface of the oil and close the lid tightly over it.
Stored as suggested, and with minimal air in the head of the container, Osmo Polyx can be stored for at least a couple of years.
Pure tung oil finishes are what we call “in the wood” not “on the wood” which means that there is very little on surface. The oils protects the wood from the inside out by absorbing into the wood cells and drying to create a water repellant durable surface. In China and Eastern Asia it has been used as a wood finish for thousands of years both interior and exterior.
The finished surface will generally darken the natural wood and feel the most natural of all out finishes, giving a low sheen ‘woody’ look. Its resistance to moisture is excellent.
Pure Tung Oil is derived from the nuts of tung trees – Aleurites fordii – native to east Asia. A quality first pressed tung oil is a pale gold brown in colour and has a viscosity somewhat like olive oil and smalls a bit like peanuts.
It is a component of many products marketed as Tung Oil but which are usually extended with other cheaper oils and also contain added toxic dryers and anti-fungals so always read the ingredients on the packaging.
Pure tung oil is an auto oxidising oil which means it will harden on contact with oxygen and gives a hardwearing natural oiled finish to all wood surfaces such as timber flooring, cabinetry, architectural joinery (exterior and interior), furniture, gun stocks, kitchen wood-ware and bench tops.
Pure tung is safe for use on wooden toys and kitchen woodwork which contacts foodstuffs such as bench tops, cutting boards and wooden bowls.
It is often used as a figure enhancing sealer under other top finishes such as shellacs and varnishes but must be allowed to dry first.
It is strongly recommended that Pure Tung is tested on an off-cut or equivalent piece of the wood that the finish is intended for. This will help ensure that your expectations are in line with a desired result. Oil finishes by their nature can absorb oil deep into the wood unlike membrane finishes which can often be more easily removed with strippers or sanding if you change your mind or are unhappy with the outcome.
Prepare the surface to be finished to a minimum 400 grit abrasive paper. Any deep scratches will become quite visible once the oil is applied. The more you can apply a ‘shine’ to the surface before applying oil, the better the finish will look. Wet the surface with a damp cloth to raise the grain and expose any poorly prepped areas, allow to dry and sand agin with 400 grit paper.
Generously apply a first coat – I spread it out with my hands rather than wasting it in a cloth or brush. Keep the area well wetted with the oil for about 30 minutes. Some areas with differential absorbency may soak up all the mix and will need re-wetting. Never allow the thick well wetted finish to dry in the sun.
After this time, vigorously wipe off all remaining surface oil with a cotton rag or similar. This may seem counter-intuitive (and expensive) but is essential to achieving a good outcome. Tung oil needs to be cured in thin coats. Failure to carefully do this is the most common reason for problems.
Next day repeat with another coat using the same technique. Give the surface a wet rub with tung oil and something mildly abrasive such as hessian or a grey scotchbrite pad to flatten out any rough areas. Buff the excess off immediately with clean rags.
This is usually enough coats but after a few more days you can repeat coats as you wish to achieve the desired lustre. The golden rule of oil finishing is more and thinner coats are better than fewer and thicker.
Ideally wait a week during which time the oil will harden. Be ready to wipe away any oil which may bleed from the surface.
The oil curing process is a slightly exothermic reaction. Do not leave oily rags balled up as there is a risk of spontaneous combustion.
Clean with a damp cloth and mild detergent. Avoid using regular household or harsh chemical detergents, as these are designed to dissolve grease and oil, and over time, will break down the oil in the surface.
DO NOT leave hand wash soap dispensers on your Pure Tung Oil finished surface. The harsh chemicals will break down the oil in the surface and leave a container shaped ring.
RE-OILING & TOUCHUPS
Wipe the oil over the cleaned surface and after some minutes wipe dry exactly as the notes suggest for initial application.
When storing, keep sealed off from air, cool and dry, out of the sun and try to expel any air from the head of the container. Stored as suggested, and with minimal air in the head of the container, Pure Tung can be stored for at least a couple of years.
The clarity of shellac goes unrivalled to any other mambrane finish and is my all time favourite finish for guitars and musical instruments. The gloss and depth you get from a good shellac finish is like looking into a crystal clear pool of water except the surface is not wet but only appears so.
Shellac is a natural, organic resin derived from the secretions of lac insects which swarm in great numbers on certain host trees. Lac insects incubate their young in the raw shellac. The tree branches coated with the lac (known as Sticklac) are harvested and processed to offer the several grades and colours of shellac available. Lac production is principally found in North-East India, Bangladesh, Myanmar, Thailand, Laos, Vietnam and parts of China.
Shellac is a also a versatile wonder product which finds numerous other uses such as a glossing coating on confectionery, pharmaceuticals and fruit as it is food safe rated.
French polishing is the application of numerous coats of shellac, which has been made into a workable polishing resin by being dissolved in an industrial alcohol, with a particular padding technique using a pad or rubber (terms for the same hand applicator – a wad of cotton wool or wadding encased in a square of woven cotton cloth). The process for large flat expanses such as table tops involves the repeated application of thin coats in circular and figure eight motions. A lubricating oil to prevent the fad from tearing into prior partly cured coats is needed when padding.
The polish is also alternatively applied with fine brushes which leave little or no brush strokes.
Shellac is flexible enough to also offer a simple and fast curing day-to-day finish. An application of a couple of coats of polish – padded or brushed on – rubbed back between coats with very fine abrasive paper, with a final very thin coat and a topping paste wax, is a legitimate and simple use of shellac which is part way to the full process. This is a repairable, durable, low toxicity finish well suited to cabinet pieces which will not have to withstand rough use such as coffee tables.
Shellac has several major positive attributes, high among them is that it is one of those few membrane finishes which are reconstitutable which means new coats will meld with old and repairs and refurbishment is made very simple.
Because shellac is an organic product, it has a shelf life when purchased and stored dry. Old shellac past its use by typically fails to cure to the hard surface expected and remains tacky. When shellac is made up into a polish its use by date is somewhat shortened, particularly for both white and blonde grades, and a useful rule of thumb is 18 months. This shelf life can be considerably extended by storing both dry and mixed shellac in a refrigerator.
We only use de-waxed white shellac as it is the closest to clear available.
MAKING FRENCH POLISH
French polish is traditionally made up as a concentrate, using a number of mixing ratios, depending on the amount of product desired in a single coat, from a ration of 1 to 3 parts by weight shellac, to 10 parts by liquid volume of alcohol e.g. 100 to 300 grams of shellac to 1 litre of alcohol. Where available, IMS100 (100% Industrial methylated spirits) is very strongly recommended, as the hardware-store variety methylated spirits will contain some water which can cause a white blooming in the finished work.
THE FRENCH POLISHING RUBBER
French polish is usually applied using a French polishing rubber. The rubber is made by wrapping a piece of worn, lint free, cotton cloth (old white t-shirt material is best) around some cotton wadding or cotton waste.
The purpose of the rubber is two fold. Firstly it acts as a reservoir to store the polish and secondly it is the applicator used to transfer the polish to the surface.
Place a hand full of cotton wadding into the centre of the cotton rag, bring in the four corners of the rag and then twist to form a pear shaped pad, ensuring that the base of the pad is flat and free from creases or defects as shown. The size of the rubber can vary according to the user or the size of the job to be completed.
Depending on whether an open grained or filled grain finish (or anything in between) is desired, will determine whether we fill the grain prior to french polishing.
For an open grain finish, sand to minimum P400 and remove all dust from the surface, then go straight to bodying up.
For a grain filled finish, do not remove the fine dust as this will mix with the shellac, along with a filler such as pumice powder, which is also a very fine abrasive.
I do not recommend using coloured fillers as timber changes colour and filler does not.
Apply the pumice by wrapping a small amount in a Chux type cloth and dusting the surface.
APPLICATION (FRENCH POLISHING METHOD)
Charge the rubber with shellac and about 50% alcohol, backing off when the surface of the rubber is not immediately absorbing. Tap the rubber on the palm of your hand (use gloves) to flatten the surface. The polish should not squelch or run. If it does, squeeze the excess out.
Work the surface of the timber in circular motions. The amalgamation of dust and shellac will form a paste and as it is worked will both abrade the surface and begin to fill the pores of the timber. Repeat this until the desired level of filling is achieved.
If you intend an open grin finish stop after about 3 or 4 coats. For a grain filled finish continue until the rubber starts to grip – stop here as at this point the finish will tell you it has had enough and it will need to be left to dry. Otherwise you may pull the surface, which will undo all your work and you’ll have to wash it off and start again.
Once the surface is dry (minimum next day), sand with P600 or P1200 wet or dry paper with a hard block and water as a lubricant, sand the surface with the grain.
Hints and tips:
- Never allow the rubber to stand still on the surface as the polish will melt into the previous coats
- The rubber must be used in a constant flowing motion while it is on the timber
- Keep a check on the face of the rubber to make sure it is clean. Clean as necessary with a clean rag and alcohol
- Regularly flatten the rubber by tapping on the palm of your hand
- Make sure the face of the rubber doesn’t wear through. Reposition the wad as necessary
- Do not let the rubber dry out. Add a few drops of polish as needed
- Never work the rubber too wet. Squeeze out excess as previously mentioned.
This is the process of building up the polish. Ideally, if we wanted to apply 100 coats, they would be applied in 3x 30 coat sessions, allowing a few hours between sessions for the coats to sink as the alcohol evaporates.
Apply the shellac in the same way as the first session. The rubber must not be overloaded as excess shellac will ridge up with the circular motions and will not flatten out. Try to never use a new rubber for bodying up as it will hold too much polish.
Applications are made by using the rubber in circular and then figure of eight motions. Apply a few drops of paraffin oil to aid as a lubricant. Apply it in drops from a squeeze bottle or with the tip of your finger. Take care not to apply too much oil as it will have a smearing effect on the surface and will need to be removed later.
The surface will tell you when it has had enough shellac because it will start to grip. Many factors will affect this, especially the temperature and humidity of the work space and the cut of the shellac.
The final pass in a session goes with the grain, passing fairly quickly and lightly over the surface. Always finish the session in this way. The rubber should always be slid onto the work from one side and off the other during the polishing stroke. Placing the rubber on the work and then starting the stroke will create a mark, which will be very difficult to remove. Likewise the same problem will arise if the rubber is stationary on the surface; this is because the alcohol will immediately start to reactivate the previous coating.
- Never let your rubber dry out. Always put it in an airtight container when not in use, even if only for a minute.
Once a sufficient layer has been achieved on the surface, spiriting off can commence to produce the final high gloss finish.
Sand the surface with P1200 and paraffin oil to remove any high spots. A new rubber must be charged with only a couple of drops of polish and twice the amount in alcohol and applied lightly and quickly over the surface with the grain (no circular motions) to remove the oil and achieve a gloss finish. The oil must be removed or spots will appear in the surface.
This method is fraught with danger for the novice. An alternative way to achieve a mirror gloss is to sand through to 2000 grit with paraffin and polish the surface with polishing compounds as you would with a car. 6000 grit compound seems to be a good allrounder.
The above mentioned practised and applied correctly, will result in what we call a piano finish. This is the highest shine and clarity of any finish and regarded universally as the best finish of all. However, this is too bright for antiques and most modern woodwork. Dulling down is the removal of the high gloss and can be done in the following ways:
- method 1. Take some 0000 steel wool and rub th surface quite hard in a circular motion until you have achieved a uniform matte surface with no glossy patches. Once this is achieved lighten up the pressure and then finish very lightly in the direction of the grain until all the swirls have disappeared, then buff out with a clean soft cloth.
- method 2. Take a dulling down brush that has fine, tightly packed bristles. These may be hard to find but a shoe polish brush will work. Sprinkle fine pumice powder on to the bristles of the brush and rub briskly up and down the grain to the required finish. Wipe off with a clean soft cloth.
Clean with a damp cloth and mild dishwashing detergent. Because of the sensitivity of shellac to harsh chemicals, it is important that you never use any other household chemicals for cleaning as they may leave stains or water spots, or even destroy the finish
Paste waxes and furniture polishes can be used.
Shellac should not be directly exposed to standing water or heat as the finish is likely to cloud.
Shellac is not alcohol- or water stain-resistant, but damage caused by either one can be easily repaired. You can buff out a white water stain on a horizontal surface (such as a tabletop) with a small amount of Liberon ring remover and #0000 steel wool.
You can repair nicks, scratches and marks caused by alcohol by adding more shellac to the damaged area and buffing it with #0000 steel wool or just applying another coat
Keep unmixed or mixed shellac in the fridge if possible. Test old mixed shellac before use by applying to a piece of glass or your fingernail and allowing a few minutes to dry. If it is still good it will be hard and won’t scratch off.
Paste wax, although not a particularly durable finish in itself can be very effective at adding beauty and colour back to an old piece of furniture. Beeswax was traditionally used but other harder waxes are also used and mixed with oils and solvents to soften the otherwise hard wax into workable creamy paste.
Paste wax is best used as a polish over an existing finish such as lacquer, varnish, shellac, polyurethane or even oil finishes.
A paste wax will add shine to a surface by filling in small scratches or voids in a finish. The finish will appear shinier and deeper because the light that was getting trapped in those scratches and voids before the wax was applied is now reflecting off the surface. On darker pieces of furniture it’s best to use a dark coloured paste wax. This will not only polish the piece but also hide some minor scuffs and scratches.
When you apply wax, you must remove approx. 99 % of it when you buff it out. If not, you will never attain a shine. You must only leave a very thin layer on the surface.
Make sure that the surface of your finish is clean and free of any dirt. If not, clean it with a mild soap and water. Take a piece of soft cloth and work the wax into the surface of the wood. Work on small areas at a time until you get used to how long you need to wait until the wax has hazed and the excess needs to be removed. Wipe off the excess with a clean piece of soft cotton cloth. Buff the surface with the cloth until you achieve an even sheen.