Preparation & Cleaning of Walls for Wallpaper

The first thing to be done is to clean the walls and ceiling. If there is old paper it must be removed; one layer of paper over another makes a thick before coating; the paste of the outer layer does not come into contact with the lime of the wall, which would have a preservative effect, and so forms a breeding-place for germs of all sorts. To remove the old paper, first try stripping it off dry; often you may remove much of it this way. Then wet it with hot water, applying it with a wet cloth, a brush, or a sponge, as may be most convenient; but if it is a varnished or enameled paper it will be well to put a handful of washing-soda (sal soda) in a quart of hot water and put it on with a brush or a swab, so as to keep the hands out of it; though it is not so very bad for the skin if not used too long.

It may be necessary with a hard enameled paper to make scratches in the paper to let the water in; it is sometimes quite a hard task to get such paper off. But in general when the paper is wet you may peel it off in large strips, and scrape off the remainder with an ordinary steel scraper; some recommend scraping with a piece of sheet zinc, as less liable to scratch the wall. Persistent wetting and scraping will get the paper off. Notice whether the paper sticks well to the wall; if it does, it will not be necessary to size the wall; if it comes off easily the wall must be sized. New walls do not need it.

If the walls have been kalsomined or whitewashed it is equally necessary to get the old material off, in the same general way as paper is removed; a scrubbing-brush is useful. If the wall is cracked or broken, it is necessary to repair it; this is usually done with plaster of paris; always try it before using; wet up a little with cold water, and see if it sets and becomes hard; if not, get some that is fresh. It must be mixed a little at a time and applied within ten minutes after the water is added to it. It may be put on with a trowel or, more commonly, with a putty-knife.

The common method of filling cracks is to cut the sides of the crack until it becomes V-shaped, then wet the sides of it with water so that it will not absorb water from the plaster of paris, and then press the latter firmly into it. But a more thorough method is to cut the crack out so that the channel thus made will be wider at its bottom than at the surface of the wall; thus it holds the plaster of paris more securely. Large holes are first filled to within an eighth of an inch of the surface and allowed to harden, and then filled flush; this is to avoid shrinkage. Whiting is powdered chalk; many mix this in equal quantity with plaster of paris, and wet it with glue-size; this mixture does not set quite as quickly as plaster alone.

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