The pulpers in modern paperindustry are not, or hardly, suitable for manufacturing fibre paper in a reliable way.
In the Dutch Mill, however, paperpulp can be made of exactly the same composition as the material of the damaged object. Big restoration studios in The Netherlands are customers of DMM. Among other things, because DMM can produce the right composition of fibre paper. It is donkey work. The maker might work for three days to find the right shade of colour of the fibre paper.
Have a look at the websites of restoration studio Sterken in Apeldoorn, and the National Archives in The Hague, where fibre paper from DMM is used.