Efficient Application Techniques
Pastes and glues
Selecting the proper adhesive is decisive for the quality of the wallpapering work. Depending on application, wall surface and type of wallpaper, special pastes or glues are necessary. For absorbent wall surfaces and paper wallpapers, methylcellulose pastes in various mix ratios are used. For surfaces that have little or no absorption, glues with plastic dispersion additives are necessary. In any case, the adhesive should be chemically neutral, transparent when dry, and non-toxic. For paper wallcoverings, simple wallpaper paste is sufficient. This normal paste is a grainy powder that is mixed with water. The right mix ratio is indicated by the paste and wallpaper manufacturers on the package and package insert.Synthetic wallcoverings on the paper backing material, such as textured wallpaper, require, as do non-woven wallcoverings, a paste with synthetic resin redispersion powder. This means it is reversible, and wallpapers pasted with it can be subsequently completely stripped off without residue. In the shops, these are called special or pre-mixed pastes, or for wallpapering machines, machine-grade pastes are available.
Paintable wallcoverings and heavy wallpapers require an adhesive with especially high initial bonding. For such coverings, strippable pastes in powdered form are not employed, but rather premixed dispersion adhesives. Paintable non-woven wallpapers represent an exception. Depending on their quality, they are pasted with strippable paste and can be stripped off in a dry state.
Prepasted wallpaper is no longer commonly available in the DIY branch. Such wallpaper strips are simply dipped briefly in water, which activates the adhesive. However, this method is not sufficient for professionals, since the adhesive power is often not strong enough, and at most sufficient for light paper wallcoverings.
Depending on the type and pattern repeat distance, the wallpaper strips are either cut in advance. When pasting, the wallpaper is cut to match the length of the wall, and then“booked”, or folded such that the top portion is 2/3 of the overall length and the bottom is 1/3 of the overall length.
If the wallpaper does not have a form-stable substrate, such as paper wallcoverings or plastic coverings with a paper backing, the pasted strip should not be hung immediately. According to the manufacturer’s instructions, the paper needs a certain “booking time”. To do this, the paper is folded up, and in the case of heavy textured wallpaper, additionally rolled up. In the case of light paper wallpaper, the stipulated booking time will be relatively short; for heavier coverings, correspondingly longer. During the booking time, the fibres in the paper swell and the wallpaper expands somewhat.
The rule of thumb is: The booking time must be kept constant for all wallpaper strips and the paste layer uniform and sufficiently thick. This is important for clean seams and proper positioning of the wallpaper. If you adhere to these simple rules, you will be rewarded with favourable results.
Non-woven wallpapers or those with non-woven substrates are even simpler to hang. Non-woven wallpaper is especially stable with regard to dimension. That is to say, it does not exhibit shrinkage due to tension from drying, there is no warping or soaking through of the paper and no tearing when pasted. Non-woven wallpapers do not require booking time. They can be pasted using the wall-pasting method. This means that paste is applied to the wall itself, and the dry non-woven wallpaper is placed on the pasted wall.
In order to make sure the wallpaper strips are hung straight, the first strip on every wall is plumbed with a distance of 51 cm to the corner. We always paper with the light, which means starting at the window. This is different for large motifs and photo wallpaper. Here, it is better to start in the middle of the optically most important wall. Generally, in the living room, this means the area behind the sofa, and in the dining room, the wall across from the window.
Wallpaper is almost always hung edge-to-edge, to keep seams as inconspicuous as possible. The strips are hung with an overhang about as wide as your hand (about 15 cm) at the ceiling and floor, then smoothed onto the wall from top to bottom, avoiding the formation of bubbles. Then the overhang at the ceiling and floor ends is cut off flush. As a rule, the wallpaper strips are all hung in the same direction and vertically. Strips are only hung upside-down when the arrow symbols on the label so indicate: In this case, every other strip is rotated 180° and hung upside-down. A relatively recent phenomenon is wallcoverings that are hung horizontally. This is aesthetically sensible for a few design-oriented wallcoverings with wide stripes, colour gradients or artistic, digitally-printed papers. In any event, you must make absolutely certain that no paste oozes out at the seams, and if so, carefully wipe the area clean.
In general, remember that sensitive wallpaper edges should be smoothed onto the wall with just a slight amount of pressure and the proper seam roller. If seams stick out over the entire length of a strip or if bubbles form on the surface, this indicates insufficient booking time, an incorrect paste mix ratio, or paste that is too thin. In such cases, the seam roller only serves to damage the edges. It is better to add more paste and glue the edges down, then regulate the amount of paste accordingly.
Detail Work – Seams, Corners and Edges
Professional paperhangers hang wall- paper edge-to-edge. The obsolete practise of hanging strips with a narrow vertical overlap is only done with thin Simplex paper wallcoverings. The general rule is: Always start hanging where the light falls.
Since the invention of the edge trimmer, seams are no longer a problem for novice paperhangers. Using an edge trimmer, even voluminous and heavy, textured wallpapers can be cut without damaging the underlying surface. For the double cut, the edges of two wallpaper strips overlap a few centimetres. Using a utility knife, the overlap is slit about 15 cm down, and the edge trimmer is then slid into the cut and the cut is extended by hand down the length of the strip to the end. Both loose cut-off strips can then be removed. If the blade was sharp, a perfect seam results. Finally, any paste spots are removed, and the seam is pressed onto the wall either by hand or using a seam roller.
Corners are fairly easy to paper. First, the paste is applied to the corner. Then the overlap is cut using a utility knife and smoother such that the wallpaper overhang is as wide as the spatula. For wallpapers with free match edges and plumb walls, the following strip can then be pasted exactly in the corner. Both strips will only overlap a few millimetres in the corner.
Even if the inside corner itself is not straight, the next strip of wallpaper should still be plumbed. When doing so, the corner will once again be over-lapped by a few centimetres. Then the wallpaper is pressed into the corner with a plastic spatula and cut along the marked pressure line with wallpaper scissors.
In the case of patterned wallpaper, this strip is first split vertically in line with the pattern and then pasted into the corner taking care to match up the patterns.
Generally, for large-pattern wallpaper, the order in which wallpapering is done must be carefully planned. It is best to start in the centre of the largest wall surface and end in an unimportant corner of the room. A non-matching pattern situation is bound to turn up, but it should be situated hidden behind a cabinet or in a low-lit corner, or perhaps covered by curtains.
If pattern and motif allow, thin paper wallpaper can also be pasted with an overlap on corners. The wallpaper strip is glued around the corner by about a finger’s breadth and the edge pressed on using a finger. To be on the safe side, the edge is subsequently re-pasted and the next strip is hung overlapping to the corner. In the case of hot-embossed or other synthetic wallcoverings, only a special dispersion adhesive in a tube will hold here.
In the case of expensive or heavy paper, the strips are not pasted to overlap. The outside corner, for instance, is covered about 15cm and shortened just a few millimetres using a steel ruler and utility knife. In this way, you can ensure that the next strip will be positioned exactly edge to edge.
Of course, in the case of patterned wallpaper, this only works if the cutoff waste is as little as possible. Two to three millimetres will hardly make a difference, but any more would mar the look of the pattern. In hotels and other well-frequented buildings, outer corners need special protection. In these cases, they are reinforced with a plastic or stainless steel corner strip. Such protective corner strips are fastened with a dispersion adhesive and evened out with filler before wallpapering. The wallpaper strip is then pasted over the corner and cut away along the ridge of the protective corner strip with a utility knife. Corner strips are also useful for wallpapers with sensitive surfaces or stubborn wallcoverings. Furthermore, when you wish to change the design from one wall to another, the corner strip helps to separate the patterns. Thus, the two different themes can be combined without allowing the edge to appear frayed or imprecise.
Nowadays, wallpaper scissors are hardly used anymore. When wallpapering around baseboards, door frames and structural reveals, it is better to use straight edges and utility knives. For window and door recesses, the following method is optimal: Hang the first wallpaper strip at the window such that the window recess is sufficiently covered. The excess is precisely cut out using a utility knife on the edge of the upper recess. Then, the wallpaper is cut off vertically in line with the corner of the recess; the next wallpaper strip is then positioned above the window, edge to edge. Finally, the overlaps are cut away with a smoother and a utility knife. The wallpaper runs a few millimetres around the inner corner, covering the gap between window frame and wall connection.
Images & text courtesy of AS Creations, Wallpaper 1×1 – A Textbook For Craftsmen and Those Who Wish To Be