Your finished job will only be as good as the preparation. Paint applied over a poorly prepared surface will not last as long or look as good. To avoid lengthy preparation, freshen up your paintwork before it deteriorates!
Choosing the right primers, undercoats and paints is an essential step in achieving excellent results. You'll find a full guide to this in the Which Paint Where? section.
Filling and Patching
This is an essential step, as any blemishes that you do not remove now will be much more visible under your new paintwork. The techniques for filling different surfaces vary, so we're going to look at filling holes and dents in both wood and masonry.
Before you start surface filling, any rotten or decaying timber must be removed and replaced.
The surface should be prepared as outlined below. Sort out the cracks, dents and holes into those which will be subject to movement (usually the joint between two surfaces or materials) and those which will be stable.
There are a number of fillers you can use. These range from linseed oil putty to cellulose-based compounds. Linseed oil putty is very common, but it becomes dry and brittle with age. Timber should be primed prior to being filled if linseed oil putty is being used. Cellulose fillers are more flexible.
To fill holes or dents, simply make sure the area is clean and apply the filler with a spatula or putty knife. If the hole is particularly deep you may need to overfill or apply a second lot of filler as it will shrink during setting.
Where you think movement is likely to occur, in places like the joints between walls and windows, an exterior flexible filler is recommended. A variety of these is available and they are usually applied direct into the crack with a caulking gun.
Masonry and Brick
Filling small holes in brick or render is simple. Scrape away any loose paint and fill the hole with Exterior Polyfilla using a broad-bladed knife or scraper. Deeper holes may need overfilling or a second application to compensate for shrinkage during setting. Use a brush or rag to roughen the filler before it is completely dry to match the texture of the surrounding surface.
Larger holes may need to be repaired with a 6:1 mix of sand and cement. Mix it dry and then gradually add water until it is of a doughy consistency. Wet the area you're going to patch and fill with the mortar using a trowel or wide scraper.
Patching compounds are available either as a powder or pre-mixed. Using a pre-mixed filler will usually shorten the drying time.
If your smoothing with the knife is less than perfect, a quick wipe with a damp sponge will take out small ridges and save sanding later on.
Surfaces must be sanded smooth before any paint is applied. Sanding can be a laborious job so if you have a significant amount to do it may be wise to consider some of the mechanical help available. See the tool check list for details. On paintwork and wood, a general purpose sandpaper can be used. On bare metal you'll find cloth-backed emery paper will last much longer and do the job faster.