If an old door has been painted and repainted many times or if its paintwork is blistered or flaking, you'll only make the problem worse if you add another layer. Stripping off the old paint can make a shabby door look like new. You could then repaint it or, if it's made of high quality wood, bring out its natural warmth by varnishing or staining and varnishing it.
Before you start, read the paint stripper instructions carefully and take all the precautions that are recommended for the product you're using. If you can, take the door off its hinges and work in a garage or workshop, especially if you have small children or pets.
Before stripping old paint (especially from before the 1960s), it's very important to check it doesn't contain lead pigments. You can do this with lead testing kit, which is quick and simple to use. If the result is positive, you must use a special chemical stripper and take all the precautions advised by the manufacturer.
Apply the paint stripper using an old paintbrush but make sure you wear protective gloves and goggles. Work it into the mouldings and corners, brushing liberally over the flat areas, and leave it for the recommended length of time. You'll see the chemical start to react with the paint and the surface begins to rupture and bubble.
Use a flat-bladed scraper to try scraping back the paint on a test patch. If the paint is several layers thick, you may need to stipple in some more paint stripper and leave it a little longer. Once the stripper has done its job, you can scrape back the paint to reveal the bare wood.
Use a shave hook to scrape any paint from the mouldings. Draw the hook back towards you, removing paint from the crevices. Carry on until you've taken off all the paint.
Neutralise the surface using either white spirit or water (depending on the product, so please check the instructions on the tin). Work it into the surface with a cloth or brush to remove all traces of the stripping solution before sanding and finishing your door.
Hot-air guns usually come with a selection of nozzle attachments. Use the one that spreads the heat over the wide area, or you can use the gun without any attachments fitted. As pointed nozzle is more likely to scorch the wood, you should only use this when you're working next to an area you don't want to damage.
Always wear protective gloves and goggles when you use a hot-air gun or handle paint-stripping chemicals and never check that a hot-air gun is working by placing your hand in front of the nozzle.
Start by stripping paint from the flat areas first. Make sure you wear protective gloves and goggles and direct the heat over a small area of paint - moving the gun slowly back and forth. Use a flat-bladed scraper to lift the paint as it softens.
Start stripping the paint from the mouldings with a shave hook. Take care to keep the hot-air gun moving, or you'll scorch the wood. Pull the shave hook towards you and work carefully on each section in turn.
A newly-stripped door will usually show previously hidden cracks in the wood or any blemishes, but you can use a wood filler to hide them. If you're going to stain or varnish your door, it's a good idea to choose a filler that matches the colour of the finished effect. This is because wood filler doesn't absorb stain or varnish in the same way as natural wood.
Wear a dust mask and sand the flat panels with medium-grade abrasive paper. Wrap the paper around a piece of wood or use a sanding block and work in the direction of the grain, taking care not to round off any sharp corners or mouldings. You could use a small hand-held electric sander, but again take a great care not to damage the mouldings. Go over the area a second time using a fine-grade abrasive paper.
Fold the abrasive paper into a suitable shape and work on the mouldings (you could wrap the paper around a piece of dowel to do this). Take care not to damage the mouldings when you're working on corners and edges. You could use fine-grade wire wool instead of abrasive paper (except on natural oak, as it'll mark it).
To sand into corners and crevices in mouldings, you'll need to fold the abrasive paper and use the folded edge to reach into the joint.
After you've done any necessary stripping, sanding or filling and your door is fully prepared for painting, take off the handles and wedge the door open, keeping the handle and spindle in your pocket in case it's accidentally closed.
If you're painting the door a different colour on each side, it's best to paint the hinged edge - the colour of the closing face and the outer edge that of the opening face.
As oil and solvent-based paints give off harmful fumes, make sure the room is well ventilated when you're applying the paint, and when it's drying.
Start with the panels (1) and the mouldings that surround them. Next, paint the centre vertical (2). Then paint the cross-rails (3), starting with the top rail and working down. Paint the outer verticals (4), and finish by painting the three exposed door edges (5).
You should use masking tape or a paint shield to protect the glass in a glazed door. First, paint the mouldings around the glass (1) with a cutting-in brush. Next, paint the cross-rails, starting with the top rail and working down (2). Then paint the outer-verticals (3), and finally all three exposed door edges (4).
Divide the door into eight imaginary sections. Start at the top left (1) and work down from left to right. Blend each area into the next, while the paint is wet, finishing with vertical strokes in line with the grain. Paint the door edges last.
Wood stains and varnishes come in a wide range of colours. But do bear in mind that the final colour may differ from the one shown on the tin, as it'll look different on different woods. You can mix or dilute wood stain to achieve a particular shade but make sure you test it on a piece of wood, similar to the door before you start.
Brush down the door and use a tack cloth to remove all traces of dust. Then apply the stain with a paintbrush, starting with the panels. Stain the mouldings first, then work around one half of the door and then the other. Always try to follow the grain and pick up wet edges before they dry. You'll need to work quickly and apply the stain evenly, without any overlap. While it's still damp, rub the door with a lint-free cloth to even out the stain and take off any excess.
Use a good quality clean brush to apply the varnish, making sure you've read the instructions on the tin. Dip your brush up to a third of the bristle length, and wipe the excess off on the inside of the tin. Let the first coat dry thoroughly and then go over the surface lightly with a fine-grade abrasive paper. After that, wipe the door down with a tack cloth and put on a second coat. If you're after a tough finish, you could apply a third coat.