Anyone fancy defining what constitutes a 'natural material' ?
Cardboard is made from wood pulp, which is nothing more than ground-up trees - ain't that natural enough ?
LJ
The majority of cardboard for packaging is impregnated with flame retardants.
These same chemicals are the most frequently found man made chemicals in the thyroid glands of marine mammals living around ports !
Cardboard works much better if its been left in the rain and then dried out, probably because these flame retardants have been washed out.