painting lime plastered walls

hi, im hoping someone can help.i have to paint some lime plastered walls on a job im doing at present,but im getting conflicting advice about the procedure.is there a special priming coat that goes on first? the walls are really damp ,so can i dry these with a de-humidifier? hope some one can be of assistance.

First you should find out why the walls are damp.If water penetrates them then no paint would stop that. Painting them could worsen the water demage by hindering the evaporation/drying.

Years ago lime was added to plaster and mortar so it dried out fairly rapidly and allowed for subtle expansion and contraction so to speak with changing humidity temperature etc. ..... for this reason it may not be a good idea to put any acrilyc paints on the plaster but go for more water based options or stick with the tried and trusted whitewash.