It is not advisable to wall-paper or panel the surface or to apply paints of high vapour diffusion resistance on it.
A good vapour-permeable paint does not form a coherent, impermeable layer, leaves the porous, mineral-like surface of the plaster free and ensures drying of the plaster and the wall. This not feasible when using vapour-tight paint.
Despite having open pores, the wall does not permeate water from around because the outer surface of the plaster and inner surface of the pores are waterrepellent.
Vapour-permeable silicate, organic silicate and certain silicate paints can perfectly be applied for dry surfaces. We can get super vapour-permeabele surface through the cheapest traditional whitewash method. A kind of rare plaster can be applied on dry plaster without limitation whatsoever, such rare plaster showing the above mentioned qualites.