Besides being inherently fragile, papers are also extremely sensitive to the environment. Excessive humidity, high temperatures and a polluted environment are factors that generally cause the growth of fungi and microorganisms.

The selection of a conservation and restoration treatment is important; the loss of supports can be replaced mechanically or by hand; there are deacidification and bleaching processes; inadequate supports can be removed; etc. All these processes aim at recovering the support structure as well as part of the image or drawing.