How do I prevent white wallpaper edges from showing?

Dear Melanie,

I am sorry to hear this, especially from a newly converted wallpaper fan. When a white line appears between wallpaper sheets after installation, it is natural to assume that the seams are open, and the wall underneath is showing. This can happen for a variety of reason and we have covered the topic extensively in our article Why do wallpaper seams open up and how can you fix them?.

However, the problem you mention seems to be of a different nature and is specific to dark wallpaper models. A thin white line showing on the edges of wallpapers (especially those with dark or patterned designs) is not due to incorrect installation but to the way wallpaper is produced. Most wallpapers, regardless of their colour, are backed by white paper. If you look at a wallpaper roll from the top you will notice the white backing.

Why do white wallpaper seams appear?

When you install your wallpaper sheets, they absorb moisture from the wallpapering paste. As they dry, they can sometimes shrink back, causing the seams to pull apart just enough to expose the white backing beneath. This is particularly noticeable on dark wallpapers where the contrast is stark, leaving those unsightly white seams that you were trying to avoid in the first place. Don’t worry though, as there are simple, effective ways to prevent this and ensure your wallpaper edges remain invisible.

How to prevent white wallpaper edges

There is a foolproof method to avoid visible white seams and it’s quite simple too. Just colour the wallpaper edges of your wallpaper roll before installing it. This ensures that even if the wallpaper shrinks during the drying process, its edges are already disguised. This is a trick that every professional installer uses to avoid these kinds of problems, and it works like a charm. Here’s how you should proceed:

Choose your colouring material

When it comes to choosing how to colour the white edges of the wallpaper, you are not going to be short of options: you can pick crayons, water-based felt pens, watercolour paints, or acrylics. Water-based options are a great option. While they do soak into the paper, any excess can be wiped off easily if it gets onto the surface. Avoid oil-based inks as they tend to stain and are difficult to remove.

Pick the right colour

Choosing the right hue is essential to achieve a seamless look. Focus on the background colour (not the motifs) and try to match it as closely as possible. If you cannot find a 100% match, opt for a slightly darker shade rather than a lighter one.

Techniques

Depending on which colouring material you opt for, different techniques are required.

A - If you are using watercolour paint or acrylic:

• Keep the wallpaper rolled up
  If you are using water colour or acrylic, don’t unroll the wallpaper just yet. Keep it tightly rolled so that you can easily fill in just the borders without risks.
• Apply the paint
  While the wallpaper is still rolled up, apply the paint along the edges. This helps ensure that the pigment is absorbed by the paper but doesn’t bleed onto the wallpaper surface. Test in an inconspicuous spot before applying the paint broadly to be sure it won’t cause issues with your particular model.
• Allow It to dry
  Let the coloured edges dry completely before starting the installation. This will prevent the pigment from smearing surfaces during the hanging process.

B - If you are using crayons or a felt pen:

• Carefully unfold the wallpaper roll bit by bit
  You will need to go over the side edge of the sheet with your crayon/felt pen, so that you can turn that unsightly white into a dark trim matching your wallpaper colour for a seamless look once it is up on the wall.
• Place the wallpaper roll vertically between your legs and apply the colour
  Grab a comfy chair, sit down and place the wallpaper roll vertically between your legs. Start unfolding one end and lightly move your crayon/pen over the edge of your wallpaper without pushing too hard. If you are using a crayon, keep rotating it to avoid creating a ridge that, once too deep, might result in some colour getting onto the front of your wallpaper. Do this all along your entire wallpaper roll.
• Turn the roll and colour the other edge
  Once you completed one side, roll it back and restart the process on the opposite edge, so that both sides are evenly coloured.

Choosing vinyl wallpapers: why white seams are less of a problem

Most vinyl wallpapers, especially those with thick plastic surfaces, have the advantage of coloured edges. Even though these wallpapers still have a white backing, the thicker vinyl top layer usually conceals it well enough that you won’t see any white seams (unless the paper shrinks dramatically).

Fixing seams that show after installation

OK, I can hear you say, this is great advice for my next project. But what about the wallpaper I have already installed? What can I do about it? If you’ve already hung the wallpaper and are noticing white seams, don’t worry. You can still fix the issue. Here's how:

Coloured pencils or felt pens

Get hold of a coloured pencil, crayon or felt-tip pen that matches the main background colour of your wallpaper. Carefully trace along the seam to colour in the white areas. Be sure to test it in a small, hidden area first to ensure the colour is a good match.

Watercolour or ink

For an even more seamless result, you can use watercolours or ink. Take a fine brush and paint along the seam. Wipe off any excess paint with a slightly damp cloth. After applying the paint, gently dry the area with a lint-free cloth to ensure the seam blends perfectly into the rest of the wall.

Final thoughts

As for many things in life, the key to avoiding white wallpaper seams is preparation. Colour the edges before installation to ensure that any shrinkage during drying won’t reveal unsightly white lines. If this advice comes too late and seams do appear after installation, carefully using coloured pencils, felt pens, or watercolours can quickly and effectively conceal them. With these simple tricks, you can achieve a flawless, professional-looking finish for your wallpapering project.