As a Professional Decorator, I have done a lot of wallpapering over the years. I’ve hung everything from lining paper and cheap Arthouse, all the way up to the more expensive Harlequin and Versace products. In this blog I’m going to explain about whether you need to prime walls before wallpapering and a little bit about the best products to use. I’ll keep things simple. Follow my advice and you’ll avoid any problems.
I’ll start by answering the question – yes you do need to prime walls before wallpapering. Different substrates take different primers (I’ll go through each in the following sections). Primer is important for a few reasons; you may need to stabilise your wall before applying wallpaper. You may just need to cut down on the absorption of the wall and aid adhesion. Or you may need something that will neutralise and block any nasties on your wall.
Priming Bare Plaster Walls Before Wallpapering
Bare plaster can be a little daunting because you’re basically starting from scratch. However, it’s one of the easiest surfaces to work on. You do need to prime bare plaster, and there are a couple of different products available. You should really line any surface before wallpapering too (see further down this blog), but if for whatever reason you’re not doing, then you may want to put a coat of paint on the plaster wall to match the colour of your wallpaper. This is just to hide the strong terracotta plaster colour from showing through any wallpaper seams that open up (probably due to the lack of lining paper).
Diluted Wallpaper Paste
Diluted Wallpaper Paste (also known as size) is the most used product to prime walls before wallpapering. You should always use the same paste as you’re using to glue your paper down. Because diluted paste is thin, it soaks into the wall and seals it. Wallpaper paste, of course, also aids adhesion.
Decorators have been using paste to prime walls for decades, and there is nothing wrong with it. It’s cheap, it’s a product you have on the job any way, and it works. However, size does have a couple of drawbacks.
It’s difficult to sand the walls after priming them with size, so any grains that get picked up by the paint roller or brush can be visible through your wallpaper.
The other issue is, size is quite tacky, so your wallpaper sticks a little bit too quickly. This can make it difficult to manoeuvre your wallpaper into position, and if you try and drag the paper across a tacky wall, then you can stretch it. This often leads to patterns not matching up, or the wallpaper shrinking once dry, and seams opening.
Beeline Primer Sealer
This is the primer I use on most of my walls before wallpapering. Beeline Primer Sealer does everything that size does, but it creates a harder film which is easier to sand, and it also gives you some “slip”, meaning you can move the paper more evenly.
I love this product. You’ll see me recommend it more throughout this blog, and it’s the one I use at work. It’s cheap, easy to use, and works a lot better than size does. It’s just a shame more people don’t know about it.
Priming a Previously Painted Wall Before Papering
Providing the paint is sound, you should treat a previously painted wall the same way as you would a bare plaster wall. However, you do need to make sure it’s sound. Scrape and sand the wall to see if the paint comes away. If it does, then you need to remove any paint that may come loose as you apply the wallpaper, or your paper will lift.
Then, as with bare plaster, the two products you might use are size (diluted wallpaper paste), or Beeline Primer Sealer. Size will do the job perfectly well, but Beeline Primer Sealer is far superior and will make your job easier.
Priming Previously Papered Walls
Walls that were previously wallpapered are a little bit trickier. Obviously, we’re talking about working after the previous wallpaper has been removed. For a start, the walls probably need more prep.
But you also need to seal in any residual paste to create a sound surface. Do any filling and sand as needed to make the surface as flat as possible, then I recommend using a product called Zinsser Gardz to prime your walls.
Gardz is fantastic! It acts as a stabiliser and as an alkali resistant primer. Moreover, you can apply a coat of Zinsser Gardz, then carry out additional prep to your wall, be it extra filling or more sanding. The only downside is Gardz is not as porous, so you need a grippy paste. Most tub pastes are fine, my favourite is Beeline Yellow Top, but there are loads of good quality wallpaper paste products. Wicks is also good, as is ProGold.
Priming Plasterboard Before Wallpapering
Plasterboard is very porous, and if you stick wallpaper to it without priming, then you’ll never get the paper off again without destroying the wall. You should prime with DryWall Sealer, or my favourite, Zinsser Gardz.
Should I Line Walls Before Papering?
I thought I’d add a little section on the need to line a wall before wallpapering. A lot of people (including some Decorators) miss this step out, but they shouldn’t. Lining paper has a few benefits. It isn’t just for hiding imperfections on a wall so they don’t show through your wallpaper.
It also helps adhesion and soaks up excess paste when you’re applying your wallpaper. It helps in more ways too: it gives your Olfa Knife something to cut into when splicing, and helps wallpaper go round external corners.
However, the biggest benefit is the way it expands and contracts when applying your wallpaper. The paste from your wallpaper soaks into your lining paper and causes it to expand slightly. Then, as your wallpaper and lining paper dry and tighten together, the lining paper pulls slightly and stops seams from opening. You will still need to prime your walls before lining them, but the lining paper will help with your overall finish.
Well, I hope this blog has helped. It’s easy really: all walls need to be primed before wallpapering. Different substrates require different primers, but providing you follow the instruction laid out in this blog, then you can’t go wrong.
Do I need to prime walls before wallpapering – by Mike Gregory