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Installation |Wall Surfaces |
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1. INSPECTING WALL SURFACES
Basic rule:
| When hanging wallpaper, wall surfaces must be dry, structurally sound, absorbent, clean, neutral and smooth. |
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Moisture...
content in plaster and concrete should be determined with a plastic foil check. Any moisture will be visible the next day in the form of condensation behind the plastic foil. Such moisture should be dried out!
If moisture continually ascends or seeps through the wall due to construction detects for example, wallpapering should not be attempted.
| Wall surface stability...
should be checked with a scratch-test by using a pointed object. Scratched areas should not burst open when applying moderate pressure. Testing with your thumbnail should leave no pressure print behind. Rubbing with the hand should not leave abrasion.
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Old chalky paint should be thoroughly washed off with water.
Old dispersion paints should be tested for durability using the adhesive tape test, and if necessary removed.
These and other surfaces not sufficiently durable to hold pasted wallpaper should be treated with a suitable undercoating in order to stabilize them.
Wet the wall surface with water in order to test absorption. If the surface is nonabsorbent, then water will run off in drops (sand the surface or apply a caustic solution). If absorption is too high: immediate dark discoloring.
2. PREPARING WALL SURFACE FOR UNDERCOATING :
old wallpaper and coatings should be completely removed. Add wallpaper-remover to water, apply and let soak in (repeat if required) and remove wallpaper. Or add 5 to 10% paste to the soaking water (water is thus effective longer when soaking wallpaper). Washable wallpaper should first be perforated or sanded. Only hang wallpaper over the previous base paper, if it firmly adheres to the wall. If wallpaper that is impervious to steam is being hung (i.e., metal wallpaper), then all base paper layers should first be completely removed.
Oil-based and gloss paint plus any oil remaining from molding or paneling of concrete are not suitable for use as wallpapering surfaces. Particularly the edges and seams of high-tension wallpaper could loosen as a result – even though dispersion pastes have been used.
Roughen such coatings with caustic solutions and wash afterwards with water. Additionally, recommendations are to use bonding coatings and to prepaste priming rolls in connection with these undercoatings.
3. PRE-TREATMENT WITH UNDERCOATINGS :
1. Undercoating treatments should penetrate wall surfaces, reduce strong absorption and neutralize differential surfaces.
2. They should provide the basis for good adhesion when working with wallpaper during future renovations.
3. They should harden plastering that is just beginning to crumble, and
4. prevent softening of the outer surface of gypsum plaster boards. This insures easier removal of wallpaper later on.
5. Undercoating treatments should not imperviously seal wall surfaces.
6.
All absorbent wall surfaces, with the exception of wood based
materials, should be treated with water-based undercoatings to insure
worker protection and for ecological reasons. |
Pre-pasting with thinned, normal or special paste is recommended for smooth, structurally sound yet highly absorbent wall surfaces. Not suitable for crumbling plaster.
Wallpaper removal primer is used so that dry wallpaper can be easily removed, strip for strip, when renovating in the future. This is especially recommended for waterproof and washable wallpaper since pre-treatment remains effective even after several changes of wallpaper.
Water-based penetrating stopper is used to harden wall surfaces, for example in the case of crumbling plaster. It is suitable for all surfaces with the exception of wood-based materials.
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