Should I Prepare The Walls
With Size or Primer?
When preparing your walls for wallpaper it is important to know if the surface is drywall or plaster, as each surface type should be prepared differently. If you aren’t sure what your wall surface is, you can chip out a small chunk using a hammer and a screwdriver (you will need to repair afterwards). If you have drywall/plasterboard you should use Primer instead.
Plaster is rock hard whilst drywall is much softer and has a paper face. If your walls are plaster, a coating of Size is an absolute must before applying the paper.
Sizing Walls Before Wallpapering
‘Sizing’ your walls, not to be confused with measuring your walls, is a very important step of adding a barrier between your plaster and wallpaper paste, to prevent the paste from being absorbed into the plaster. This helps the paper to stick better.
Sizing solutions are available at most DIY and Hardware stores. They are typically a gelatinous solution that is mixed with water and applied directly to the wall with a pasting brush or roller.
Applying size also makes it easier to slide and position your wallpaper, and should you want a fresh look and decide to hang new wallpaper several years down the road, the ‘size’ will make it easier to remove the wallpaper from the wall.
Priming Walls For Wallpaper
Primer works in much the same way that sizing does, but with a few notable differences. Oil-based primers are the best choice if the surface is a basic painted drywall. Acrylic primers are better if you are hanging new wallpaper over existing wallcoverings, this is especially true when the existing surface is vinyl. Acrylic primers are available with color, which can be helpful if you’re concerned about the old paper’s colors or patterns showing through.
Note: Never use an oil-based product on an existing wallcovering, as the oils can soften or dissolve the old pigments and cause them to bleed through to the new surface.
Sizing Walls with Paste
Can I use wallpaper paste to size a wall? Yes you can. A common practice is to use a runny mix of wallpaper paste to size the walls. Most paste manufacturers will include instructions on their packaging regarding the correct proportions of powder and water to make a substitute ‘sizing’ solution. A good rule of thumb would be to use an extra 20-25% more water.
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