The number one cause of paint failure is when the surface is prepared poorly. The first and most crucial step is preparing the surface you are about to paint.
Preparation:
- Wash the surface with mild detergent or sugar soap to remove dirt. Treat any mould and allow to dry
- Any interferences need to be removed such as electrical face plates, knobs, handles, locks etc. Anything that cannot be moved can be masked or covered where possible.
- Any imperfections or loose paint needs to be sanded. To ensure the new paint can bond to the surface any gloss surfaces need to be dulled by sanding. A mask is important to be worn when sanding and also ensure the dust is cleaned up afterwards.
- Old paint or varnish on wood needs to be removed entirely so use a paint stripping gel, wash down and allow to dry then sand lightly
Painting the surface
- Any marks need to be sealed with an appropriate sealer so that it avoids bleeding through to the new paint. New, repaired or patched surfaces will require a coat of primer or undercoat before painting. Check the label on the topcoat tin for priming instructions on the surface you are painting.
- Water based paint can generally be painted over existing water based paint without an undercoat if the old coat is in good condition.
- Oil based paints will require an undercoat if the old and new paint is oil based or if using a water based topcoat you should undercoat with a primer-sealer-undercoat
- Bare wood needs to be primed with a wood primer or a primer-sealer-undercoat to ensure long term adhesion of the paint and avoid any tannins from the timber staining the new topcoat
- Rust needs to be removed and the metal primed with an appropriate metal primer