Stripping Old Paint (Removal)

The simplest test takes a few seconds. Run a dry palm across the wall. If a white powder comes off on your hand, the surface is "chalking", and it is very likely distemper. The second test uses a wet sponge. After a few wipes, distemper softens, smears or starts to wash off. Emulsion stays firm.

Why does it matter? A chalky layer is soft and has little strength. New paint will stick to it, but it sticks only to that powder. As the new coat dries it shrinks, pulls the weak layer with it and starts peeling off in flakes, often within a few weeks. Ordinary masking tape gives you a third test. Press a strip firmly onto the wall and rip it off quickly. If a lot of old paint comes away on the tape, the surface needs cleaning back.

Limewash is usually harder and chalks less. One or two sound coats can sometimes just be sealed with a suitable primer. Thick, cracked or flaking layers of limewash should come off as well.

In older properties it is worth keeping two other things in mind. Old gloss or oil-based layers underneath may contain lead, so do not dry-sand anything you are unsure about. Textured ceiling coatings can contain asbestos. If a ceiling has a textured finish, do not scrape it. Have a sample tested first and use a licensed contractor if needed.

For distemper, the wetting method is used almost every time. Water softens the paint, so you need no sanding and no chemicals. In practice the job goes like this:

• Preparing the room: move out or cover the furniture, lay plastic sheeting on the floor and put paper or cardboard on top, which soaks up water and stops you slipping
• Protecting the electrics: switch off the circuit at the consumer unit and tape over sockets and switches, because water runs down into them
• Wetting: soak the wall with warm water using a roller, a large brush or a garden sprayer, always working in small areas
• Waiting: let the water work until the paint softens, usually roughly 10 to 20 minutes, longer and repeated on thick layers
• Scraping: pull a wide scraper or filling knife across the surface at a shallow angle without digging into the plaster
• Washing: wash off the residue with a sponge and clean water until the wall no longer chalks
• Drying: let the wall dry thoroughly before the next steps

Scraping is usually followed by filling cracks and holes, a light sand and a coat of primer or stabilising solution. The primer binds the surface and evens out how much it absorbs. These are separate jobs, but they belong to a good paint finish.

The same area can take an hour one time and a whole afternoon the next. The effort, and therefore the cost, depends mainly on:

• Number of layers: one thin coat of distemper comes off almost by itself, ten layers from different decades need soaking again and again
• Type of finish: chalk and glue-size distemper softens quickly, limewash more slowly and sometimes takes more effort
• Ceiling or wall: ceilings are physically harder, water drips and you work from a stepladder or a mobile platform
• Condition of the plaster: if wetting reveals hollow or crumbling plaster, repairs are added
• Details: cornices, ceiling roses, mouldings, corners and window reveals are done slowly by hand
• Empty or furnished room: an empty room is quicker and carries less risk of damage
• Mould: affected areas need a mould treatment, and the cause of the damp has to be found

Plasterboard is a special case. It must not be soaked, because the paper facing would absorb water and start to lift. Wet it only lightly and scrape very gently.

A handy homeowner can strip distemper from walls. You need no chemicals and no noisy tools, just patience. Ceilings are messier and need a stable working platform, so many people leave them to a decorator. Wear safety glasses, because drips containing lime irritate the eyes.

1. Test the wall with a dry palm and a wet sponge to confirm it is distemper.
2. Move the furniture out, cover the floor with plastic sheeting and absorbent paper, and tape down the edges.
3. Switch off the circuit for the room and tape over sockets and switches.
4. Get a bucket of warm water, a roller or sprayer, a wide scraper and a sponge ready.
5. Wet an area of roughly one to two square metres.
6. Wait until the paint softens and wet it again if needed.
7. Scrape off the softened layer in strokes from top to bottom, keeping the blade flat.
8. Wash off the residue with a sponge, changing the water regularly.
9. Move on to the next area until the whole wall is done.
10. Leave the wall to dry, usually at least a day depending on temperature and ventilation.
11. Check the wall with your palm and a strip of tape before filling and priming.

It often happens that only the flaking patches are scraped and the rest is painted over. The new paint then sits on old chalk and eventually peels even where the wall looked fine. Another mistake is poor washing. If the wall still chalks after scraping, the primer has nothing to grip.

Blades that are too sharp or too much pressure are also common. The scraper then gouges the plaster and you end up with extra filling. Impatience causes problems too: filling or painting a damp wall leads to patchy results and poor adhesion. And do not underestimate water near sockets. Switching off the circuit and taping over the fittings takes a minute.

Whether you are signing off a decorator's work or checking your own, look for these points:

• The wall leaves no powder on a dry palm
• Masking tape pulls away no traces of old paint
• No islands of old distemper remain, especially in corners, along skirting and around windows
• The plaster has no deep gouges from the scraper
• Hollow or crumbling areas are marked and agreed for repair
• Floor, windows and door frames are clean, with no dried residue
• The wall looks and feels dry before the next steps begin