Work out why the paint won't dry, fix the conditions, remove it if needed, then repaint properly and let it cure.
PT-01Work out why it's still tackyCheck how long ago you painted it. Water-based paint should be dry to the touch within a few hours and hard within a day or two. Oil-based paint (gloss, satinwood) can take 16-24 hours to touch-dry and up to a week to harden fully, so it may just need more time. Tackiness after that usually means the room was too cold, too damp, or the coat was applied too thick.
PT-02Test it properly, don't just prod itPress a dry lint-free cloth flat onto the paint for a few seconds, then lift it straight off. If the cloth sticks or leaves fibres, it's still curing. Try an area that hasn't been touched at all, since fingerprints and smudges can make a dry surface feel tacky.
PT-03Improve the conditions in the roomOpen a window or use an extractor fan to get air moving, but avoid a strong draught blowing dust onto wet paint. Aim for a room temperature above 10°C, ideally 15-20°C, since cold and damp are the main reasons paint stays tacky. If the room is humid, a dehumidifier or just leaving the door open to a drier room helps a lot.
PT-04Leave it and retest before doing anything elseGive it at least 24 hours in the improved conditions, then repeat the cloth test. Don't be tempted to add another coat over tacky paint, as this traps the problem underneath and makes it worse. Patience at this stage often solves the problem without any rework.
PT-05Remove the paint if it's still tackyFor water-based paint, sand it back gently with fine abrasive paper (120-180 grit) until you reach a dry, sound layer underneath. For oil-based paint that's still soft, wipe it off with a cloth dampened with white spirit before it skins over further, then sand any remaining residue. Wear disposable gloves, and work in a ventilated room.
PT-06Clean and dry the surfaceWipe the area down with sugar soap solution to remove dust, grease and any sanding residue, then rinse with clean water on a fresh cloth. Let it dry fully before repainting; damp surfaces are one of the main causes of tacky paint in the first place.
PT-07Repaint in thin, even coatsStir the paint well and apply thin coats rather than one thick one, since thick coats trap solvent underneath and take far longer to cure. Follow the recoat time on the tin, and use a paint suited to the room, for example a quick-dry or kitchen-and-bathroom formula in damp rooms.
PT-08Let it cure fully before touching itKeep the room ventilated and at a steady temperature while the paint cures, and avoid touching, leaning on, or closing doors and windows onto the fresh paint for at least 24-48 hours. Full hardness can take up to a week, especially for oil-based paint, so treat the surface carefully during this time.
PT-09Tidy up and dispose of materials safelyAny cloths or rags used with white spirit or oil-based paint can be a fire risk as they dry, so lay them flat outside to dry fully before binning them, rather than screwing them up in a bag. Rinse water-based paint tools in water, and clean oil-based tools with white spirit, then wash your hands thoroughly.