Is 100% recycled paper sustainable?
No it is not. Manufacture and use of paper damages the fibres, and there is a practical limit to the number of times a fibre can be recycled, before it has disintegrated. It is not easy to establish what that limit is, but the real limitation is the collection efficiency. Currently Australia recycles about half the paper it uses, which means that only one fibre in 32 gets recycled more than 5 times, for example.