You can use whatever you want for your decking, but if you want to achieve more than just cleaning, that is, get a treating effect, a scrubbed floor surface, then you need to use a superfatted soap.
Let us add that all soaps are good if the choice is between soap and something else, regardless of the manufacturer, but soaps have different properties depending on which oil/fat they are based on.
Tall oil gives a greater excess of fat, while linseed oil and rapeseed oil give superfatted soaps.
For all natural materials, you should therefore choose a superfatted soap such as Västerbottenssåpa.
Questions and answers
1. Are all soaps the same?
Answer: No, soaps get different properties depending on which oil they are based on
2. Which soaps are superfatted?
Answer: Västerbottenssåpa and linseed oil soaps are naturally superfatted
3. Which soap should you choose for natural materials?
Answer: A superfatted soap like Västerbottenssåpa
Order natural cleaning products here: Västerbottenssåpa