Can I Soak Card Before Adding into the HOTBIN?
No. However paper or card is an essential part of the HOTBIN composting process to help control moisture levels.
Why do Some People Advise Soaking Cardboard?
Soaking cardboard is usually done for one of two reasons; it makes the cardboard easier to tear and/or it speeds up the decomposition process. This is only valid though if you are working with a cold composting pile, the HOTBIN as a hot, aerobic composter requires these materials to be treated differently.
How Will Soaked Cardboard Affect the HOTBIN?
Adding paper/card into the HOTBIN is a requirement because it absorbs any excess moisture as it is mixed in with the waste that you add. If you pre-soak cardboard or paper this paper/card is then already pre-loaded with moisture which means it has no capacity to absorb anything else. This may also create aeration problems as it prematurely sticks together forming blockages in the contents of the HOTBIN. In the end your HOTBIN contents will cool down and you will notice an increase in leachate coming from the unit - the risk is then the contents could become anaerobic.
Always cut or shred dry paper/card before adding into the HOTBIN to avoid creating layers which may restrict airflow throughout the unit.