finishing woods

FINISHING

wood is finished for performance or aesthetics, finishes can change the colour or enhance the grain of a wood. treatments may also be applied to prevent insect and fungal attack or to increase the woods resistance to moisture. finishes can also seal timber to protect it for pollution

wood finishes can be applied in different ways depending on the situation, wood must be sanded along the grain and white (methylated) spirit can be used to remove grease and dust this also make smoother finishes be taken in more easily by drying the wood. when wood is pressure treated it must be done in an industrial setting, whereas in workshops, brushes, clothes, rollers, pads and sprays can be used as long as ventilation is present for safety

USER APPLIED FINISHES

when applying finishes the area must be prepared with ventilation and space to avoid accidents and staining

polyurethane varnish - used for tough and hardwearing finishes that need to be used a lot and resistant to heat, chemicals and moisture. it is formed from plastic suspended in a solvent and can come in matte, satin or gloss, it can be used clear or tinted and often for wooden flooring. overtime PU can yellow with age

PU varnish gives a lustrous finish but it can look fake, there are also water based alternatives to reduce the environmental impact and more durable versions but they are more dangerous, PU varnish also creates noxious gases when drying

acyclic varnishes - used for covering paint to increase durability. it is milky white but gives a clear finish that dries faster. it is hardwearing but less durable than PU varnish. some advantages are that is is non toxic and produces very few odours

water-based paints - needs a primer or undercoat, and it comes in many colours, it is suitable for interior woodwork and furniture as it does not release VOCs that can pollute the atmosphere, it is also toy safe as it is water based

primers and undercoats go before a finish to take paint and finishes batter, they also seal the wood allowing for a stronger colour to be seen

stains - used to change the colour of the wood without hiding the natural grain of the wood, they are purely aesthetic and can be used to mimic wood tones of other woods, but however do not provide protection

colour wash - used for a distressed finish for a shabby-chic aesthetic, it is often applied with a brush and then rubbed with a rag to remove most of the wash leaving texture, however no protection is provided

wax - used to create a natural look that also protects against moisture, wax is often applied in multiple layers and can be buffed with a lint-free cloth for a shiny finish. certain waxes are produced for a food safe finish

oils- used to increase the grain and create a non-toxic food safe finish. oils can also enhance naturally occurring woods’ textures. oils need to reapplied on average once a year, Danish oil is a mix of oil and varnish for a water resistant and durable finish, it can be used as a primer and is food safe. Teak oil is good for hardwoods that need UV protection and are used outdoors, it is not suitable for high traffic areas

MACHINE APPLIED FINISHES

pressure treatment can be applied on timber using a copper based preservative for antimicrobial properties, it is used to prevent weathering and biological attack and is called tantalising.

wood is rolled into the chamber and then air is pumped out to vacuum air out of the timber cells, then the preservative is added to the chamber and hydraulic pressure forces the treatment into the wood. vacuums extract the preservative and then the lowering of pressure redraws the treatment in, this can create a green tint in the wood