Acrylic paint on untreated pine...........

[zephyrcat]

Will that work or would I need special paint? Am intending to varnish over as well so wondering if the acrylics would be ok with that?

yes. will be fine.

Should be ok - is the pine very knotty though? The knots can leak resin which will discolour the paint. You're meant to treat them with "knotting". Can't remember if Varnish does the trick too though.

It's not too knotty but does have some small, very dark ones. The colours I want to use will be quite light - ie pinks - do you think it would show through?

It can do - it's come through white paint on some of our internal doors. Google should be able to tell you if varnish would seal them or if you need to seal small ones.

Are you wanting a wood finish? If not, I think you would be best to put on an undercoat so that the wood doesn't absorb all the paint.

No I don't - I'm hoping for the paint to be 'solid' colour..what type of undercoat would I have to use?

You can get away with watered down ordinary paint TBH. It soaks into the wood and seals it.

B&Q sell proper undercoat/primer though. It'll say "for bare wood" on the tin.

or you can get a primer/undercoat combined