So far, so good! We've prepared properly; we have

Corners are rarely square and true, and simply hanging the wallpaper without taking this fact into consideration can lead to big problems as the strips are hung. What starts off as a 'slight' out of trueness? Will increase and become more pronounced as we progress. The effect can be awful; as the pattern runs off at an ever increasing angle.

Internal Corners.

The best way to tackle internal corners is to paper towards the internal corner, but stop at the last full length (and roll width)of wallpaper you've hung before the corner, then measure the short gap (something less than the roll width) at the top and bottom. Add about 10-15mm extra to return the paper in and around the corner.

Using a pencil and a straight edge, draw a line on the paper, from top to bottom. The measurement between the top and bottom may vary; but don't worry; it'll work out just fine. When you have cut your strip; paste it and allow soaking as before.

Brush the paper smooth and flat with the cut edge firmly pressed into the angle of the corner, so the slight overlap returns onto the adjoining wall.

Tip: if the short edge, into and around the corner will not lie flat; then make a series of short scissor cuts down the edge. This should then be easier to flatten down; use more paste if needed as things might start drying out due to the extra time these fiddly bits can take.

Now, before hanging the next strip (on the wall adjoining the corner) deduct the same measurement you overlapped by; 10-15mm, or whatever you overlapped by, and mark a new plumb line on the wall at this point. Hang this next strip by butting the edge of the paper against the new line, and return the extra bit round the corner onto wall you've just finished.

Again, using the scissors, mark a line down the angle of the corner to mark your cut-line. When done, peel back and trim. You may need to add a bit more adhesive to allow slide-ability and to stick the edges together neatly in the corner, when done, wipe down with a damp sponge or cloth.

External Corners.

When planning your starting point, consider also external corners. As you offer up a roll of paper at the start of the project; working out how many strips you will need, and where things begin and end, make it so the last full strip before a corner overlaps the external corner by approximately 25mm. Paste and allow soaking and then hang the piece in position, overlapping the corner by the 25mm extra you have allowed. If it starts sticking up at the short edge; then as before - cut short nicks along the edge; this will make it easier to stick down.

Tip: Feather the edge of the short return by carefully peeling a narrow strip down the full length of paper. This breaks up the machine cut edge, hiding the unsightly seam that would otherwise show through on the next strip you hang.

Next, mark a new plumb line on the wall of the next piece for hanging, but add on about 5mm-6mm. Hang the next strip from the new plumb line with the other edge overlapping by the 5mmor 6mm you have added.

Hang the strip in position and smooth down as before. Trim both the top and bottom edges, and roll flat with a seam roller, but again, only if the paper is not relief or embossed.

Then carry on, till the next obstruction.