Fitting a Wide Strip into a Narrow Wall Space in a Corner

I have to cover 15″ width of wall with a strip of wallpaper that is 27″ wide. Working with that 27″ wide strip and pushing it into the corner, and getting paste all over the woodwork, and trying to not get creases in the paper … all very difficult.

My solution is to trim the wallpaper to fit the corner. Here the strip has already been cut, pasted, and booked (folded pasted-side-to-pasted-side). I’ve determined that I want the new strip to be 15″ wide. This will allow enough to cover the wall space, plus the 1/2″ inside the little space between the wall and the door trim.
Because wallpaper expands when it gets wet with paste, to get an accurate measurement, I’m trimming after the strip has been cut, pasted, and booked for a few minutes, and has expanded to its maximum.
This is called wet trimming. Alternately, dry trimming is when you measure and trim an unpasted and unfolded strip.

My straightedge is set at 15″ from the left edge of the wallpaper. I’ve used a single edge razor blade to make the cut.

Here is the strip in position on the wall. I’m using a plastic trapezoid squeegee wallpaper smoother to push the right edge into the small space between the wall and the door molding.

You can see how nicely the wallpaper wraps around the corner and tucks into that narrow space.

The pattern is called Garden Party and is by Rifle Paper, which is made by York, one of my favorite companies.