Sealing and protecting hardwood oak flooring
All oak floors that are not prefinished must be sealed against dirt, discolouration and moisture. Clear sealants can be applied to bare sanded wood or wood which has been painted or stained, or the sealant itself can be tinted to add colour to the floor. There are three main types of sealant: waxes, oils and varnishes. All are applied after the oak floor has been laid.
Although the least practical, wax is the most beautiful of these options nothing can imitate the soft warm lustre of a well-maintained waxed floor. Traditionally, a beeswax and turpentine mixture was used, but this is not resistant to water, alcohol or everyday wear. Today it is possible to obtain hardwearing natural waxes specially formulated for wooden floors and usually derived from the leaves of the Brazilian carnauba palm. There are also a number of excellent synthetic waxes which are by-products of the petrochemical industry You will need to reapply a wax finish about three times a year over the entire wood floor, any damage can easily be repaired by adding extra layers of wax and buffing regularly In order to prevent successive coats of wax soaking into the wood apply a very thin coat of polyurethane varnish or button polish and allow to dry before applying the wax thinly with a soft cloth.
Oil has the benefit of being naturally water-resistant and easily applied. You will need to apply three to four coats of oil to seal bare wood completely, with perhaps a further coat of wax to protect the finished surface against wear. Tung oil, derived from the seeds of the Chinese tung tree, is extremely resistant to heat, water and alcohol and is the main constituent of many oil-based floor sealants. Used on its own, it will take about four days to dry between coats. Danish oil, a mixture of tung oil and various driers and other agents, will dry within two to four hours and is particularly hard-wearing Teak oil is also produced from tung oil, but with the addition of boiled linseed oil which gives the finished wood floor a darker colour.
Varnishes were originally made from boiled linseed oil and natural resins. Although tough and hard-wearing, traditional varnishes took about three days to dry, during which time dust and dirt could ruin the tacky surface. These have now largely been superseded by quick-drying urethane compounds produced by the petrochemical industry, which are still generally known as varnishes.
Early polyurethane varnishes were inflexible and unable to respond to movement in the wooden floor, which resulted in crazing and cracking. However, modern water-based acrylic urethane co-polymers are flexible, colourless and resistant to heat, dirt and water, making them ideal for any location. In general three coats should be enough to protect the wood against normal use, with an extra coat in kitchens and bathrooms. Gloss or semi-gloss polyurethane varnish forms the toughest surface, while matt versions are less durable.
Polyurethane is much easier to apply when thinned, but each progressive layer should be less dilute. To ensure a good finish, allow each coat to dry completely, and then sand lightly before adding the next one. For an extremely long-lasting seal, two-pack varnishes, which need to be used within a few hours f mixing, are also available. When applying any kind of varnish, it is essential to wear a mask and to ensure that the room is well ventilated and dust-free polyurethaned floors are very easy to clean using a damp cloth or mop, but once the surface has broken down there is no alternative but to sand the entire floor and apply a new coat.
A very high-gloss and resistant form of varnish, lacquer is tougher than polyurethane although considerably more expensive. A lacquered finish is created by building up successive layers of translucent glaze, which can be tinted a wide variety of colours. One benefit of lacquer, apart from its beautiful glossy sheen, is that it settles into a smooth coat without brush marks when dry.
If you have chosen presanded and varnished wood flooring systems, you will usually need to apply a single coat of the manufacturer's finish after laying but will not have to reseal the floor for many years. Whatever sealant you use, you should always try your intended treatment on a small area or a sample of the same timber and wait till the treatment is dry, including trials with the type of polish you anticipate using in the future. Most reputable manufacturers will have a range of colours varnishes and stains suitable for their products. Avoid using products that are more than a year old.