Finishes
Wood is natural product with characteristics unlike manmade materials.
In a centrally heated home, wood will dry out and be almost totally immune to rot and woodworm. It may split, depending on the wood, its shape and where in the log it came from and any treatment or polish will be for cosmetic purposes. Suitable finishes could be Danish oil, beeswax polish or both or neither. Over time, sunlight will cause timber to change colour and or fade and there are some finishes which claim to be UV resistant and reduce this effect.
Left outside, wood will weather and rot and preservative treatments will reduce rather than eliminate this process. Preservatives will soak in best when the timber is as dry as possible i.e. after a prolonged dry spell. Most timbers will go silver grey in time when left outside; realistically, to prevent this you will need to apply a product such as one from the Sikkens range which is coloured, UV resistant and micro-porous. Sikkens recommend retreatment every 18 months to maintain the finish. Horizontal surfaces which are exposed to both sun and rain are the ones which deteriorate most.
Outside
The biggest single issue with finishing timber for the UK is the location; if timber is outside the surface finish will be treated harshly by the combination of sun and rain, especially on horizontal surfaces:
- Timber will loose moisture at times and if this is relatively rapid it will 'push' a finish off and cause it to flake. For this reason, micro-porous finishes are a significant development and unlike varnish will allow the moisture vapour to pass through without so much tendency to flake off.
- The other issue is that UV (ultra violet light) will tend to bleach wood in time so unless you want the wood to go silver-grey the finish will need to contain a UV filter - generally a colour.
- Also, where the timber is on the ground, it will be very wet for a lot of the year and it will rot. For this reason, the contact faces of any outside wood should be well soaked in preservative. This won't keep the wood dry but it will slow down the bugs and fungi that want to eat it.
The best product I have found so far, and what I use on virtually all gates is Sikkens HLS light oak colour. Sikkens' Technical Support suggest using more coats of the HLS in difficult circumstances rather than the Filter 7 product as a top coat. In either case, wear and tear will remove at least one coat every 18 months and I would recommend recoating annually to keep outside woodwork looking new.
There may be other products suitable for mahogany or teak but I do not use either of these timbers.
Inside
For inside furniture, I would normally use Danish Oil; it enhances the colour of the wood, protects it from normal spills, is heat resistant as far as making coasters unnecessary for your cup of coffee, and if it is damaged, it is easier to repair than most other finishes. A surface treated with Danish oil can also be polished with a beewax polish to bring out the best in the wood and, if necessary, the surface can be recoated with Danish oil without removing all the beeswax.
Looking After Your Furniture
Outside woodwork finished with Sikkens' products should be recoated annually to keep them looking new. If untreated, it will go grey over time but oak will maintain strength for years even if neglected; how long will depend on its moisture content.
Inside woodwork, such as a kitchen table, could just be scrubbed regularly which in time will give a textured, grey surface known as a scrubbed finish. Oiled surfaces benefit from being treated with a beeswax polish occasionally. If left in direct sunlight all timbers will fade over the years although the colour could be recovered by rubbing down and re-oiling.