Clients from Wrexham and Chester often ask me this question. The simple answer would be ‘because the manufacturer recommends it and without lining paper the manufacturer is not obliged to consider any claims against unsatisfactory performance or appearance of the wallpaper’. That still doesn’t answer the question though. Why use it? What does it do? What is it’s function? It is often explained that lining paper will smooth out rough walls, bridge grooves of wood or even hide textured surfaces – it won’t, not without a heck of a lot of preparation anyway! Lining paper will give a uniform surface for the finished paper. Over time, walls will get filled and filled or painted with different kinds of paints. This means that areas of the wall will become more porous than others. Therefore, by hanging a finished wallpaper straight onto the wall it will dry at different rates creating numerous problems such as seam-splitting. Perhaps the most beneficial aspect to lining paper is that it helps fight seam-splitting of the finished wallpaper. Like all paper, wallpaper, when wet, expands. When it dries, it shrinks. This natural process wants to pull the seams apart. The goal is to securely anchor the paper before it has chance to shrink. Because lining paper is absorbent, it quickly takes the moisture away from the pasted finished paper. This locks down the paper in its expanded state, preventing shrinkage and seam-splitting. Wallpaper will never fully shrink back to its original size once its on the wall and the paste is dry, but it wants to. This puts quite a bit of lateral force on the wall, and this force does not go away with time. It forever pulls. Any paint under the paper that is weakly adhered to the wall will be pulled off, causing the wallpaper to fail as a result. When lining paper is installed under a finished paper the two layers of paper will actually pull against each other and negate the net forces on the wall. Simply put, when lining paper is used with wallpaper they become one piece of paper, similar to a sheet of plywood. Considering manufacturers recommendations, the look lining paper gives and the problems it solves it is easy to see why Lee Harvey Painting & Decorating and many other professional decorators, as well as wallpaper manufacturers, recommend the use of lining paper.