1416 Painting walls made from Tufo

Wonder if anyone out there can help on this one. The walls and ceiling of the staircase leading to my flat are made from Tufo (volcanic rock) It is partially internal and partially external and consists of quite a large area with two landings. The finish is extremely rough and it has been painted white many moons ago. It now looks very dingy and I wanted to paint it cream. I asked in the paint shop about external paint and was told there were 3 types, but I didn't really understand what the difference was! I bought a 10 litre tin of one type which turned out to be artex or similar. It covered only a very small area and that took 3 hours to apply! I thought I'd try one of the other 2 varieties but a friend said it wouldn't make much difference to the amount of time needed to get the paint into all the holes, although it may have gone a bit further. Another suggestion was to have the whole area rendered, but the quote for that was 1800E then it would still have to be painted.
If anyone else has had to tackle a similar project I'd love to hear from them. What about spraying paint on?
Linda

Category
Building/Renovation

Not sure if this will be helpful to you but this is what we found ....
we discovered that all the paint we bought needed to be watered down considerably (although that then made it very sloppy to apply).
Also it seemed to go on transparently (so it appeared that it was not covering at all) but once it dried it was opaque so the coverage was marvellous but you can't see it at the time you are actually painting (and can't really see the bits you have missed until much later).
Having said that, this was just paint we purchased specifically as 'pittura murale' so wasn't made for Tufo but you might see the differences we experienced from what we would have expected to use in England (ie common or garden emulsion) and what we ended up using (which seemed to contain a large proportion of silicone).
There is obviously a reason for the difference and maybe one of the forum members who have much more experience than me can explain why the paint is so different from Uk paint??
Look forward to learning some more on this one,
Lesley & Brian

Thanks very much to Lesley & Brian and Will for insight into the world of paint in Italy! I'm afraid that diy rendering would be beyond my capabilities, to say nothing of my reach (being only 5.00ft tall) I'm inclined towards the watering down of another of the outdoor paints (not the artex this time) and may well have a go at spraying it once I have covered over the stairs. I'm not going back again now until Christmas but will let you know how it goes.
Linda