Emulsion question

[Geo]

I picked a nice Ivory coloured emulsion for my living room. I recently stripped all the wallpaper off it, but when the emulsion dries it dries a lot darker that what it should.

I used the same emulsion in my spare bedroom and it dries to the colour it should be, but the living room colour is darker.

The spare bedroom has lining paper whilst the living room has bare walls.

Does the living room walls need for sort of undercoat, if so what ones would you recommend. I did go over the walls with white emulsion to lighten them.

Cheers

[Handy]

It isn't necessary to prime previously wallpapered plaster, only bare new plaster, and emulsion doesn't need undercoat, it needs two coats. The emulsion needs to go on thick enough, but not too thick so that it runs. What colour is the plaster on the bare walls, is it light grey? If so, two thick coats of emulsion, allowing sufficient drying time between, should result in the colour on the tin. But if the plaster is a dark colour you may need to apply 3 coats of emulsion. Even a light colour one coat emulsion might need two coats on a dark surface.