decorating advice please.

[cupcakes]

I have picked three colours from Farrow and Ball and have to choose one to decorate new extension (if you're interested they are Blue Grey, French Grey and Pigeon). I have painted testers on each of the walls and on the bare plaster they look great but on the one old wall which is currently painted white they look awful - really murky and drab.
I was planning on painting it white with a cheap emulsion as an undercoat so that the F&B paint doesn't just soak into the plaster and goes further. But will it look like the paint on the white wall - or could that just be a badly lit wall (it isn't...)
sorry about the rambling post.

cant visualise these colours, but I am painting our lounge the same colour as our kitchen and it looks completely different between the two rooms, kitchen is better lit than lounge, why not put a dab of white on all walls with tester colours over to see if they look as bad as the wall youve done.

Good idea.

They look murky and drab because the patches are surrounded by white! That's all.

And yes, you need to seal the new plaster with cheap watered down emulsion IIRC.

MT - yes, it is aparkling brand new plaster.

I really don't think the colour looks different because of the surrounding white - it is genuinely really different. Instead of these beautiful greyish bluey greens they are murky olives.

Paint a whole piece of paper and hold it up against both the new plaster and the white. That'll be a safe test.

The intensity of the grey colour will vary from one wall to another depending on light levels and times of the day, iyswim.

I always seal new plaster with unibond or wallpaper paste before painting it

we used specail plaster stuff before painting our new plaster. Think it was from Dulux