Civil Engineering Reference
In-Depth Information
fibres. It is also quite normal to add fibreglass to an otherwise pure natural tex-
tile in order to strengthen it.
Wallpaper made of paper consists of cellulose, preferably in the form of recy-
cled paper. In certain cases formaldehyde products are added to increase resis-
tance to water. The printed pattern on the wallpaper is often glue-based paint, or
emulsion, oil or alkyd paint. Until 1960, paint based on animal or plant glue was
the usual paint used for printing wallpapers. Paper wallpaper often has a thin
plastic coating to improve its washability.
Plastic wallpapers are based on a structure of paper or a natural textile, and
usually consist of softened PVC. It can be smooth or textured. In Sweden, about
3000 tons of vinyl wallpaper is used every year.
Wallpapers of natural textiles are based mainly on renewable raw materials.
Fibreglass fabric is made from quartz sand, which is considered to have rich
reserves. Plastic products are based on oil, which is a very limited resource.
Plastic production has a negative effect on the environment (see 'Plastics in
building', p. 147).
If the wallpaper contains volatile substances, these can also cause a problem in
the indoor climate. Considerable emissions of styrene have been measured from
fibreglass reinforced polyester wallpaper, increasing in damp circumstances
(Gustafsson, 1990). PVC coatings have a high level of emissions which can irri-
tate the mucous membranes. Fibres from glassfibre paper are probably too coarse
to be carcinogenic. Both textile and paper wallpapers cause no problems so long
as no hazardous glue or other volatile substances have been used. However, if
the glue is exposed to continuous damp, mould can arise.
The 'shagginess' factor can also cause problems. Large amounts of dust can
gather on rough surfaces, giving rise to the growth of micro-organisms.
Electrostatic charge also plays a role: the large negative charges in PVC wallpa-
pers attract dust of the opposite charge. PVC wallpapers in themselves are also
potential growth-beds for micro-organisms. It has also been observed that PVC
wallpapers shrink as the softener loses its strength, allowing gaps to appear
which can harbour dirt and give rise to mould.
Softeners in plastic wallpapers create a sticky layer if they are warmed which
catches dust and soot.
When renovating or demolishing, it is usual to remove old wallpaper from
walls. This is quite easy with paper wallpapers. Steam or hot water can be used
on the soluble pastes. It is more difficult with plastic wallpapers. Wallpaper for
bathrooms which has a foamed PVC underlay is difficult to remove, and will
often take a piece of the wall or plaster with it. Wallpapers have no recycling
value. Paper and natural textiles can be composted, providing they have no pol-
luting or potentially dangerous additives or adhesives. Fibreglass wallpapers
which contain polyester and PVC wallpapers have to be deposited on special
tips.
