Preparing the surface on painted walls: Unless the paint is flaking or the surface is uneven, painted walls do not have to be stripped. However, make sure that the surfaces are completely free of grease and dirt. To give the new wallpaper something to grip on – especially if the surface is gloss – block-sand the surface and wipe clean. Bare walls: Freshly plastered or rendered walls and walls that have been stripped to the plaster can be papered over with little trouble, providing they are free of damp. Your first task is to make good any chips or cracks in the surface with filler and to sand down bumps and bulges.
Wallpapering may look simple, but it is all too easy to get into a mess unless you know the right way to do it. Most of the techniques involved are easily mastered and will help give your walls a professional touch.
Preparing the room
Start by removing as much furniture from the room as possible, then remove all wall hangings – such as pictures, mirrors and lamps – together with their fixings.
To mark the future positions of the fixings, stick a steel pin into each wall-plug – later, you can hang wallpaper over the pins and leave the fixings clearly marked.
For the small blemishes normally encountered when redecorating, use either a cellulose-based filler in powder form (such as Polyfilla), or a ready-mixed vinyl-based compound which comes in tubs.
Cellulose fillers are the cheaper of the two and are suitable for most internal uses, but the hard-drying qualities of vinyl-based fillers come in handy where the cracks result from expansion due to heat – around hot water pipes for instance.
The secret of using filler is to apply a little at a time, waiting for each layer to dry before you apply the next. In the case of powder fillers, mix enough for just one layer at a time – an old tennis ball cut in half makes a good container.
Before you apply any of the filler, brush away all loose debris from around the hole and blow away any dust. Use a flexible filling knife or an old kitchen palette knife to force the first layer well into the hole. While it is drying, clean the knife and scrape away any excess filler from the surface of the wall.
Continue building up the filler until it is just proud, then smooth it off with the knife. When the filler is dry, use fine glass paper on a cork sanding block to sand it – and any other bumps – flush with the wall.
Sizing or painting the wall with a suitable compound, evens out the absorbent qualities of the plaster or render and creates a smooth surface on which to wallpaper.
Soaking and scraping tends to be a messy job and if just water is used to soften the paper it can also be hard work. So where medium and heavyweight papei-s are concerned, you can add either proprietary stripping compound or some vinegar or acetic acid – available from chemists – to the water. All these reduce the surface tension of the water, helping it soak into the paper more quickly and break down the old paste.
Normally, the mix is simply painted on with a distemper brush. But if you are dealing with PVA-coated washable paper, you may need to score the surface with a wire brush so that the stripper can penetrate through to the wall. Leave the stripper to soak for a few minutes, then use a stripping off the loosened paper with the other. These operations soon become continuous with practice, although the thick layers of paper may require more than one application.
Preparing to paper
A good working surface on which to cut and paste the wallpaper is essential. Ideally, you should use a pasting board about 25mm narrower than the paper you are hanging. Alternatively, use a sheet of chipboard or a flush-faced door – laid over a pair of trestles or the kitchen table. To help you reach the top of the walls, you will also need at least one pair of steps. Make sure that these are safe.
Arrange the equipment so that you can work on it comfortably and using a cellulose wallpaper paste use this as your sizing compound. For starch pastes a bone glue size is available. Vinyl wallpaper pastes require their own, special size. Leave the wall to dry thoroughly before you start hanging your paper. Walls already papered: In most cases, it is inadvisable to lay fresh paper over an already papered wall – over-papering causes the paste between layers to interact, giving rise to additional problems such as peeling, staining and blistering.
However, with vinyl-laminated paper, it is sometimes possible to peel away the vinyl layer from its paper backing strip. If the backing paper remains firmly and evenly pasted to the wall, you can paper directly on to it.