Wallpapering tools in Detail: Cutter knife and seam knife
Cutter knives with a segment blade are universal cutting tools for wallpapering purposes and can - after some practice - replace the seam knife for double seam cuts. Cutter knives are available at varying prices, but the quality is always crucial for a good cut. Seam knives or double-cut knives were developed especially for double seam cuts. They can cut through two overlapping lengths of wallpaper and create a perfect and clean transition.
Cutter knives - characteristics, variations and use
Cutter knives can be equipped with a so-called segment blade (where segments are broken off when they become blunt) or a fixed trapezoidal or hooked blade.
The most popular cutter knife (i.e. the one with a segment blade) is used in many households and is suitable for wallpapering, among many other uses. The blade is divided into regular segments with break-off grooves. Once a segment has become blunt, it is broken off with pliers and reveals a new sharp segment.
The number of times a segment blade can be broken off depends on its width, thickness and cutting length. Commercially available standard blades have a width of 9 mm, a thickness of 0.38 mm and a cutting length of 80 mm with 12 segments, or 18 mm width, 0.5 mm thickness and 100 mm cutting length with 7 segments. The blades can be replaced once they have all been used. When purchasing premium quality models, you will usually receive a pre-equipped cutter knife plus about 5 replacement blades. Replacements blades can be purchased as sets with a number of blades.
Oiled blades made from HCS steel are equipped with a handle or slider made of plastic or light-weight metal. There is a small hole at the end of the blade which is used to fasten it to the handle with a screw. High-quality cutter knives with additional comfort and safety often have segment blades with a metal guide which is covered in an ergonomic plastic or aluminium casing. In order to move the blade back and forth, there is a small guide clip attached to the knife.
Prices for cutter knives range from about 1 to approximately 10 Pound, and it is always worth investing a little bit more in a premium model to ensure safe and clean results.
Cutter knives are used to place precise and clean cuts on wallpaper that is already on the wall, for instance at overlaps along skirting boards, the ceiling, around door frames or windows. For best results, the wallpaper shouldn't be too damp and should have had time to dry sufficiently on the wall. In order to create a clean cut, always use a ruler or a cutting edge. The cutter knife is also used to put a cross cut above switches and plug sockets. In addition, it is also suitable for subtle and clean wallpaper repairs.
If the blade is of good quality and sharp, only a minimum of pressure is required. If too much pressure is applied, the plaster (or, for windows and doors, wood/plastic) can be damaged.
Seam knives - characteristics, variations and use
The seam knife is designed for the so-called double seam cut, i.e. when lengths of wallpaper have been put up with an overlap and an accurate cut is needed to create a clean seam. Its metal blade bracket is equipped with a so-called 'stilt' to guide the blade. It holds the blade in position so that a straight cut can be made through both lengths of wallpaper without the blade veering out of line. This also provides the user with a much improved "feel" for the double seam cut.
The stainless steel blade has rounded corners as well as three holes to fasten it to the blade holder or bracket via a threaded pin and a knurled nut made from nickel-plated brass. The short handle is fixed directly to the blade holder or sits just above it. The blades are replaceable and widely available. Some slider cutters come with a replacement blade set (usually ten pieces). The price for this specific cutting tool is about 6 Pounds, Seam knives are suitable for any type of wallpaper and surface.
Cut like a pro with cutter knives and seam knives
Our wallpapering guide How to wallpaper corners provides details as to the correct use of cutter knives and how to successfully apply a double seam cut. With the right tools and our useful instructions, the best results are guaranteed.