It depends on how they look. If they are discoloured and there are clear signs of growth (black or green), it is a good idea with Deep Cleaner A and B. These products will also remove oil from previously treatments.
Exterior Cleaner is not that effective, but in return, it is not that harsh a treatment of the wood.
For the deckings, we recommend WOCA Exterior Cleaner which can be washed away with the garden hose without damaging the lawn.
No, not if you treat them with oil. The oil will always awake the glow and darken the wood.
But you can omit oiling them and then in return clean them more often with Exterior Cleaner. Then you will have nice silver-coloured furniture, which is not that dirt-repellent but then you compensate for that by cleaning them more often.
No, Deep Cleaner A is basic and cleans completely. Deep Cleaner B is acid and neutralizes A, in other words it stops the process. When Deep Cleaner A has had the desired effect, you scrub Deep Cleaner B into the wood. If necessary, you can also let Deep Cleaner B soak into the wood as it also makes the wood lighter. Now, you must clean with plenty water. Nothing happens if you clean off Deep Cleaner A before you treat with B.
Yes, the wood is now completely clean; micro-organisms and dirt for example have been removed. But now, the wood is very open and completely unprotected. The wood will look plain again very fast if you do not oil again.