It is important that you learn trade terminology (trade words). Many painters and paper hangers understand the terms they use or a particular name they use, whilst these may mean something quite different to another paper hanger; both can be technically correct.
For example: As wallpaper comes off the roll and is cut it is called by all of these names length, strip, drop, piece. Each name can mean the same thing. Another similar example is the name used to describe the meeting of two drops to each other; join, joint or seam.
Wall coverings can be pre-pasted or un-pasted.
These wall coverings have adhesive (paste) applied by the manufacturer, in powder form, on the back. You need only to dip the paper into water to soften or re-activate the adhesive, then, to pull it out and apply to the wall.
These wall coverings require an adhesive to be applied, this is called paste. The paper hanger would normally apply the paste to the back of the paper by brush, however rollers or pasting machines are also used.
Here are some great videos for apprentices and staff on how to hang wallpaper:
Wallpaper patterns repeat themselves down the length of the paper and across the width of the paper. This is set up by the manufacturer and incorporated into the manufacturing process during printing. These repeating patterns have to be identified to avoid excess wastage of wallpaper and also that one drop will span complete from cornice to skirting.
Horizontal joins in finish wallpaper are discouraged and recognised as poor workmanship.
There are three types of wallpaper patterns: