1 Strip off old paint

Window frames are generally narrow pieces of wood and will only take a limited number of layers of paint before their details are obscured. Strip off the old finish carefully, taking care not to break the glass windowpane.

2 Fill and rub down

With the old paint removed, check the frames for damage or rot. Fill any cracks, treat the timber with an appropriate timber preservative where required and lightly sand the wood. Clean off dust with a damp cloth.

3 Mask off

To ensure that no paint gets on the windowpanes, use low-tack masking tape and mask off. Leave a very slight gap - 1.5-2mm is enough - between the edge of the glass and the frame so that the edge of the paint seals the join between them.

4 Painting sash windows

Pull down the top sash and paint the meeting rail of the top sash and the accessible parts of the vertical members; reverse the position of the sashes and complete the top sash. Paint the bottom sash and then the frame - not the runners. Paint the runners only when the frame is dry.

Using a Paint Shield

You can buy specially designed plastic and metal shields to help you paint straight edges without getting paint onto windowpanes. They can be a little tricky to hold in place, but are good if you are 'touching up' paint.

Useful Tips

• Remove masking tape as soon as the paint is touch dry. Don't leave masking tape on for too long or it will be difficult to remove.
• Painting the glazing bars of window frames is easier if you use a cutting-in brush, which has bristles cut at an angle to let you work right up to the glass with a thin line of paint.
• Keep casement windows open while they dry: if you have removed the catch and stay, keep the window open by wrapping a short piece of coat hanger wire around a nail in the underside of the frame.