In article , "David Hearn"
says...
I'm thinking of putting up a dado rail but have a few questions.

Firstly - I've seen pre-primed MDF versions or plain pine versions
(cheaper). Which are better? What kind of work would need to be done for
the pine ones before fitting? The tag said to seal it on all sides first -
what should I use to do this? We plan on using gloss paint as the final
coat. I assume the MDF would require less preparation - just fix to wall
and paint, whereas the pine would require sealing before fitting and then
painting afterwards.

Secondly - most of the corners in our room are corner, but there is one
external corner which is curved. What is the best way of getting the dado
around the corner? At worst case, I could just stop the dado at each side
of the corner and just leave the curved part without the rail.

I've filled gaps in picture rails (where pipework had been removed)
by building up with polyfilla and hand shaping with a surform - a bit
laborious but can look good if you're careful. If you wanted to try
it I'd suggest cutting a template to match the dado from thin board,
so you can scrape it over the filler to get the inital profile right.
Or maybe you could cut lots of slots in the front of a piece of dado
so it will bend around the corner, fix it to the wall then fill the
gaps. I know this is bodgery, but as I said it can look good if it's
done well. Having lived in a house with curves and dado rail I know
how crap it can look if it's just mitred as if it was a square
corner.