How to Cut and Trim Wallpaper Neatly
Blade discipline, the crease-then-cut method, when to use scissors instead, and why almost every ragged edge comes down to the same two mistakes
Crease the paper into the angle first, hold a broad filling knife along the crease, and cut against it in one steady pass with a fresh blade. Snap the blade on every few cuts. Almost every ragged edge comes from a blunt blade or from cutting without creasing first.
Trimming is the part of wallpapering that shows. The seams are designed to be invisible; the cut edges at the ceiling, the skirting and the architraves are what the eye actually lands on.
Blade discipline
A snap-off knife has segments for a reason. Damp paper blunts a blade quickly, and a blunt blade does not cut paper. It drags it, which tears the edge and pulls the length slightly out of position.
- Snap the blade on every few cuts, and always at the start of a new length.
- Snap it immediately if you feel any drag at all.
- Keep the used segments in a jar or the knife's own disposal slot, not on the floor.
- Heavy-grade paper blunts blades faster than the traditional paper. Buy more of them than you think you need.
The knife-and-crease method
The standard method, and the one to learn.
- Crease. Run the back of your smoother firmly into the angle, at the ceiling line, the top of the skirting or the edge of an architrave, so the paper takes a clear fold.
- Position the broad knife. Hold a 100mm filling knife or a trim guide along the crease, pressed flat, held firmly.
- Cut along its edge. Keep the blade at a shallow angle to the wall and cut in one continuous movement.
- Slide, don't lift. When you reach the end of the knife, keep the blade in the paper and slide the knife along, then carry on. Lifting the blade and re-entering leaves a visible step.
- Peel the offcut away gently, and wipe any paste off the skirting or ceiling immediately with a clean, slightly damp white cloth.
The scissors method
Useful on a tricky shape, or if you find a knife unnerving on a fresh wall.
- Crease firmly into the angle.
- Peel the top of the length back from the wall.
- Cut along the crease line with wallpaper scissors.
- Smooth the length back into place.
It is slower, and on a pasted wall the peeling-back is fiddly. It gives a very controlled cut on curves and awkward mouldings.
Cutting lengths before you hang
- Roll the paper out printed side up on a clean flat surface.
- Measure and mark lightly in pencil at both edges, allowing 3cm at each end for trimming.
- Cut against a long straight edge with a knife, or fold the paper squarely, crease, and cut along the crease with scissors.
- Cut every subsequent length by matching the pattern to the previous one before marking.
Check the cut is square by laying the new length on top of the previous one. A cut that is a degree or two out shows as a wedge of white at the ceiling.
Wet or dry?
On pasted paper, trim while the paper is still damp, because it cuts more cleanly and the crease holds better. Do not leave it so long that the paste starts to grab; trim each length as you finish smoothing it, before you move on to the next.
Peel and stick is trimmed dry, and needs a sharper blade for it: the adhesive layer blunts an edge quickly.
Awkward shapes
- Curves: relief cuts every 2 to 3cm, then crease and trim.
- Mouldings and architraves: crease into every change of direction before you cut anything.
- Pipes: slit up to the pipe and cut a small hole where it meets the wall.
- Coving: crease against its bottom edge and trim there; do not try to run paper onto it.
Why edges go wrong
- Blunt blade. The commonest cause by a distance.
- No crease. Cutting freehand against an angle you cannot see.
- Lifting the blade mid-cut. Leaves a step you cannot hide.
- Knife held too upright. Cuts into the wall and tears the paper edge.
- Trimming too late. Dry paste grips, and the paper tears rather than cuts.
How do I cut wallpaper in a straight line?
Crease first, then cut against a broad knife held flat, in one pass, with a sharp blade.
How often should I change the blade?
Every few cuts, and at the start of every length. More often on heavy-grade paper.
Should I trim while the paper is wet or dry?
Damp, for pasted papers, because it cuts more cleanly. Dry for peel and stick.
Knife or scissors?
Knife for straight runs, scissors for complicated shapes if you prefer the control.
Why is my cut edge ragged?
The blade is blunt. Snap it and the next cut will be clean.
What tool do I cut against?
A 100mm broad filling knife or a purpose-made wallpaper trim guide.
