Most modern window frames are made from durable and long-lasting polyvinyl chloride (PVC.) Painting over PVC may seem like a daunting task because of its non-porous nature, but with careful preparation and a suitable primer and gloss or acrylic-latex paint, you can brighten up dull-looking PVC windows by painting them any colour you wish.
Add two to three squirts of dish-washing detergent to a bucket of warm water. Wash the PVC window frames thoroughly with a cloth soaked in the solution to remove all dirt and dust. To remove stubborn stains, use a PVC- or vinyl-cleaning solution; follow the manufacturer's guidelines carefully and always wear protective gloves. Wait for the PVC surface to dry.
Scour the PVC surface with a hand sander fitted with 220-grit sandpaper in a gentle circular motion. PVC is non-porous, so sanding the surface allows the primer and paint layers to adhere better.
Stick masking tape around the edges of each glass pane to protect them from primer and paint. Press the tape into place gently so that it's easy to remove when you've finished painting. Cut off any excess tape with a utility knife.
Apply a PVC primer to the window frames with a regular paintbrush, or if the primer comes with an applicator, use it. Wait for the PVC primer to dry according to manufacturer's instructions. In general, PVC primers need at least 90 minutes to cure.
Apply gloss or acrylic-latex paint with a 3-inch paintbrush. Use a latex paintbrush for acrylic-latex paint and the cleaned regular paintbrush for gloss paint. You may wish to add a second coat of paint for a longer-lasting finish. If you do, clean the brush first with turpentine. Wait for the first layer of paint to dry before applying the second layer.
If using a specialist PVC paint, you may not need to sand the PVC surface or apply primer. However, you will still need to thoroughly clean the PVC before painting. Always check the manufacturer's instructions. PVC is also known as uPVC or PVC-u.
Wear protective gloves when using PVC primers or specialist paints.