Use a sponge to scrub the area of paint around your bare plaster. Unless the plaster is in perfect shape, you will need to patch it with joint compound. As the plaster dries, a ‘sinter skin’ forms as the binder migrates to the surface. Remove the towel and wipe away the bits of plaster using a sponge. It's not always necessary to remove emulsion, especially if you are simply redecorating with paint or wallpaper. Whether you’ve chosen to use new plaster emulsion or a mist coat, the process is the same. You need a crew to remove the old plaster, acid etch the pool, apply a bond coat, and then a crew will come out and shoot the plaster out with a hose. Primer and paint can be extremely difficult to remove from your flooring. Sand the wall to level the surface, remove the dust and clean all stains with degreaser. Use a paint brush to carefully line the edges of your walls. New plaster is extremely porous, so if you use undiluted paint, the paint’s moisture will be sucked up by the plaster.
You will then be given a few upkeep instructions.

If you are painting over it and it's not all flaky, just paint over it with a couple of coats. However, its effectiveness for removing paint from plastic varies depending on several factors, such as how long the paint has set and the type of paint.

Protect your floor in advance to save yourself headaches later. I have completely stripped a room to decorate and as the plaster is in pretty good nick was intending to sand it down to remove paint, dried glue and any excess filler.
Therefore, you must seal the plaster before applying the finish paint. Usually, a light sanding and cleaning suffice. The cloths also collect flakes of peeling paint, making cleanup easier. Stripping pre 1978 paint can be risky if it contains lead. Once the plaster is dry it should be light with no dark spots and a consistent colour and appearance throughout. If lead is present, a new plan should be made. I have a similar scenario so thought I would tag it on to this post rather than start a new thread (hope that's OK). Peeling latex paint must be removed before you repaint a plaster surface, or the new paint won't adhere properly. – shirlock homes Jul 23 '12 at 10:42 This softens the emulsion, making it a little puffy and easier to remove. So, you have taken the time to carefully and lovingly apply plaster to a wall or ceiling, and understandably you are itching to finish the job and add a lick of paint. If the stain has been on the wall for several months or longer and won’t come off with detergent, brush a primer over the stains. To remove them, mix a mild dishwashing detergent, like Dawn, with warm water and apply it to the stains with a sponge or rag as shown. Let the plaster dry. Vinegar works best on latex paint. Scrape the emulsion off the plaster using a wallpaper scraper. Dig out all the soft and loose material from the wall surface. Check the condition of your plaster. Cover the floor area with plastic sheeting or drop cloths to protect it from paint-removing chemicals. In both cases the surface of the plaster is highly absorbent when new. In modern gypsum plasters these can be quite variable, especially if the plasterer has trowelled the plaster hard to get a very smooth finish. I’m trying to remove many layers of paint (at least 3 colors) from original 1928 plaster walls. Boil a kettle. Hold the boiling water to the wall to apply the steam to the emulsion paint. Heat distilled white vinegar on high in the microwave for about 60 seconds. ... Prime the wall with a new plaster emulsion or mist coat. Get a test kit and know for sure. Follow the procedure also around the edges of the damaged area. A week should be long enough to let it completely dry out and for all damp patches to disappear. For water-based paints, seal the plaster with one or two mist coats. My wall has layers of thhick flaking paint on the surface, but under that there are areas where something like much more watery paint has been used.