Thank you everyone. It's quite strange - he fell asleep while wearing a BBOS (the furry marbled orange one
) and so I put him in his bed. The insert was the BB one with the mf and 2 layers of hemp (?). When he woke up, the insert wasn't sodden and was doing very well, but the legs of the nappy where the elastic is was all damp and would have gone through to his vest but for the fact I unfastened it for him before he slept. Is this just a normal part of cloth nappies? I'll definitely try stuffing the pockets with other fabrics, though, alongside mf.