Painting over painted wallpaper

[stealthwolf]

Our "boxroom" has been lined with plain paper and painted by the previous owners. One of the walls is dark blue, the remainder are white and come with scuff marks.

I'd like to repaint the whole room white. I was planning on just painting over the existing paint.
Do I need to prep the current painted surface in any particular way?
How do I block out the dark blue colour? Should I use Zinsser BIN/cover all? Or just paint lots of layers of white?
Any pitfalls to watch out for?

 

[Nige F]

Block the blue with cheap oil based undercoat - or quality "obliterating" emulsion. As long as it's not vinyl silk on there you'll be fine to go with white emulsion over the white.

 

[opps]

The white undercoat recommended by Nige F will be a lot cheaper than BIN. The only downsides will be drying times and smell. You can speed up the drying time by adding some Terebene. Not much you can do about the smell.

Should you decide to go with BIN, do not under any circumstances use a bog standard foam roller. The alcohol in BIN causes the foam roller to double in size (in all dimensions, resulting in a comedy-esque double length floppy roller).

 

[stealthwolf]

Thanks for the advice. Some stupid questions please:

1. How do I know if it's vinyl silk as opposed to say soft sheen or matt emulsion? The painted surfaces feel smooth, shiny and there's no chalkiness on my hands when I run them over.
2. I was looking at Dulux Supermatt emulsion as an obliterating layer. Does this sound reasonable?
3. If it turns out to be vinyl silk, what can I do instead?

This is essentially an interim paint job to brighten up the room, which includes painting over the "feature wall" which is dark and depressing.