Interior wall painting advice please?

You can try a primer for a base coat. "Kilz" brand has a great primer that comes in white. This helps the top coat spread better with less sploching or bleed through.

Read through most of the answers on this question, and some good advise has been givrn.

New plaster does not need 6 months to dry out these days, but new plaster mst have been primed first. The correct paint process should be:-

First coat: Alkaline resisting wall primer. This will stop the natural mineral salts in the plaster attacking the extenders found in all paints

Second coat: Water based primer. This will help to even out surface porosity, and prevent ;hot spots'

Third and fourth coats: The emulsion colour of your choice. You are correct to use a roller, it is faster, but for a perfect finish a good quality brush should be used.
When rollering, do no try to spread the paint too thinly, as this will cause areas of the wall to have 'roller lines' showing

Hope this helps with the remiander of your project

The answer to your question is apply a watered down coat of emulsion to your walls then apply 2 neat coats. The reason you are having patches in different areas is because the plaster is sucking in the paint much more in different places.

You will need to give the wall another one or 2 coats of paint. You're doing the right thing using a roller.

If the wallpaper is in such good shape and not too bold in color i would just paint right on top of it rather than go to the hassle of messing with plaster and old paint. trust me: plaster is not something most painters know how to deal with. talk to a plaster master (LOL) before u mess with it. ps the answer about kilz is correct and don't buy your custom paint at lowes/

The first coat doesn't paint. It soaks in. The new plaster should have been given a piss coat, (thinned with water). Then reapply 2 further coats.

You cannot get a decent finish with one coat of paint, specially on new plaster, the first coat should be a waterdown paint, this is called a miscoat, then followed by 2-3 good coats, no wonder your seeing patches lol if you have only done one coat.

I am working in a house at the moment, and I am painting new plasters HSL, ceilings and walls, and I have coated them all with a coat of white first even the walls I do with white, saves a bit of money using the colour as a miscoat, this then shows up any imperfections, and there is quite a few, then I have done 2 more coats on the ceilings, and will do final coat tomorrow, so thats 4 coats on new plaster, (havent started colour on the walls yet, but will do 3 coats on top of the white coat already there. but you do get a lovely finish.

When you say 're-skimmed', do you mean a skim coat of joint compound was used and not a traditional plaster? If joint compound was used, then it should dry within 24 hours or so, depending on temperature and humidity. Without looking at the wall I'm only guessing but I have a feeling that you may not have put on enough coats of primer. For a newly skimmed wall, I would use two coats of primer and let that dry for 48 hours before putting on a top coat. Using a roller is a good idea but make sure you have enough paint in the roller. It's almost an art getting the right amount of paint on the roller. Load up the roller and start in the top corner of one wall. First make sure that you have edged along the ceiling first. Start rolling in a small area (about 2'x2'). If the roller doesn't roll well, you've got too much paint on it. If it makes a 'sticky' sound, you've got too little. Eventually you'll get it. Start in this small area and paint a 'W' on the wall. Then roll perpendicular to this from the top down and cover the 'W'. Then load the roller up and keep going. If you have more than one can of paint of the same color, mix both together in a large bucket to ensure uniformity of color.

Add another coat or two. Many people think that because of the thicker 'one coat' paints that's all they need, but most of those one coat paints are based on applying them to a well primed surface. Also you can't have to many coats some people think the more paint you add the darker it will be, this is not the case. If you were to paint 100 coats in one spot it will not be any darker once a good coverage is achieved. Look at the color in the can it is 12 inches deep and it isn't any darker than the paint chip you used to select the color.

I usually load my roller and start out rolling a giant "W" on the wall.
When I've rolled that out a bit I'll roll perpendicular to my precious strokes. But don't roll it out too thin. Primer isn't your problem unless you're drastically changing colors. Then you can have your paint store mix Kilz in the new color and put it on first. It's less expensive than paint and will make your life a lot easier.
If plaster needs to dry six months how can they build a new house from start to finish in two?