FILLING & PATCHING
This is an important step, as any blemishes you do not remove now will be even 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 plaster.
The surface should first be prepared as outlined in the following steps. Now try and 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.
Where movement is likely to occur, in places like the joins between walls and architraves or skirting boards, a flexible filler is recommended. A variety of these is available and they are usually applied direct into the crack with a caulking gun.
There are a number of fillers you can use where no movement is expected. These range from linseed oil putty and plastic wood to cellulose-based compounds. Plastic wood and cellulose-based compounds are easier to use. Simply make sure the hole or dent 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 may shrink during setting.
Plaster Board and Hard Plaster
Filling small holes in plaster board or hard plaster (plaster applied over a cement render, usually on brick or block walls) is simple. Scrape away any loose paint, plaster or face paper (the paper covering on plasterboard) and fill the hole using a putty knife or scraper. Deeper holes may need overfilling or a second application to compensate for shrinkage during setting. If the edges of holes are cracked and unstable, a self adhesive patch will make the job easier. These are available in several sizes.
Larger holes in plasterboard will need a patch inserted. Outline the damaged area and cut away the damaged section. Use contact adhesive to put in wood or plasterboard backing strips then fix the patch onto the strips, again using contact adhesive.
Cracks should be opened up to a v-shaped channel and any loose material removed from around the edges before filling with a plaster filler.
It's worth remembering that most cracks are caused by structural movement, which fillers cannot prevent. So you may find cracks re-appearing as a result of continuing movement.
Patching compounds are available either as a powder or pre-mixed. Using a pre-mixed filler will usually shorter the drying time, but they are more expensive.
If your smoothing with the knife is less than perfect, a quick wipe with a damp sponge before the filler sets will take out small ridges and save sanding time later.
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. The Interior Tool Checklist has details of sanders and sandpapers.
Plaster And Patched Areas
Sand smooth with medium and then fine grade
Sand with medium grade paper, going with
Previously Painted Surfaces
A light sanding may be required to smooth out imperfections, depending on the quality of the previous paint job. Gloss or semi-gloss surfaces should be sanded thoroughly to roughen the surface so the paint will form a strong 'key'.
A FINAL CHECK
Before painting, give the area a final clean and check Try to remove as much dust as you can, vacuum the floor and remember to wipe over the walls thoroughly with a damp cloth or, for woodwork a cloth soaked with methylated spirits, to remove dust.
Your final check is important. There's nothing worse than having to stop and go back to patch and fill or sand once you've started painting.
Storing paint cans upside down will form an airtight seal and prevent a 'skin' forming over the surface.
An artist's brush will help you pick out details in extra colours quickly and neatly.
Paint exterior doors and windows early in the day, pro them open to dry and they will be ready to close by nightfall.
Weather to paint
If it looks like rain' remember the painter's rule; if you wouldn't hang the washing out or wash the car, don't paint!