How to prepare walls before wallpapering
This is part of a series, How to prepare walls before wallpapering . Here I explain how to check walls before stripping off wallpaper; tips on how to strip wallpaper with a smile on your face…and now, how to make sure the “bare” walls (or ceiling) are ready for wallpapering or lining.
Unfortunately, once you have stripped the wallpaper, there is still more preparation work to do. Sorry! Please don’t jump the gun straight onto lining and painting, lining and wallpapering… tick off the sanding, filling, sanding, and sizing first.
Do not forget to sand before filling, sanding, filling, sanding
That wasn’t a typo! With the best will in the world, when you strip paper, there will be traces of the old paste left behind, plus little pimples and bumps and loose specks of plaster or traces of the wallpaper.
If you fill straight away, or even worse, if you get straight on with papering, you will probably end up with loads of imperfections.
You need to avoid this contamination, (and improve the finished look, and reduce time spent sanding and smoothing back over bumpy filler). Therefore I would recommend sanding the walls the moment the plaster has dried out. Use a coarse grit paper with a sanding block. Be vigorous and thorough, but not too mad! As a guide, this stage should take no more than 30 minutes. When sanded, you should brush or vacuum the surface for a dust free surface.
Do not forget the filling
Modern plaster(board) walls. Even though you have removed all the paper, sanded, and the plastered walls look ready to paper, I would still allow up to 2 hours to check over every surface, filling any small cracks and dings.
For me, filling means I fill once; sand; second fill; sand the walls again. I recommend vacuuming all the walls too, leaving the surface smooth, ready for further decoration.
In an older property with lath and plaster walls Even if the walls look OK, with the paper stripped, bagged and thrown out, I would still allow half a day for filling and sanding. And if the walls are in a bad way, (flapping, bulging and crumbly) I would make a call to an experienced plasterer to patch and match before any further decorating work was done.
Some tips about filling and sanding walls for wallpapering
Rake out cracks with the edge of a scraper. Take a blade and just slightly open up the joint. Clean it out with a vacuum or blow hard. You have given the filler something to grip to. Deep cracks should be dampened before filling in layers. Or 2-pack Dulux filler will work in one swipe plus a quick skim.
Fill each crack slightly proud of the surface.
Sand with a sanding block Once the filler has dried hard, sand the whole wall area with 80 grade abrasive paper on a sanding block attached to a vacuum extractor. The sanding block I use is 4 x 10 and is preferable to holding the sandpaper in your hand. Not because it is so kind to your hands, but because it levels out the surface better.
Last step, vacuum the tops of skirting boards and clean the floor. Repeat the filling, sanding, cleaning process.
As professionals, we are beholden to make sure a job lasts, and looks good too. 70% of my work is prep. It is easy to undercut someone who does a thorough job of preparation. That’ll do attitudes are cheap in the short run… but you pay for it in the medium and long run.
Sizing – Next step on How to prepare walls before wallpapering
Once cleaned, filled, and sanded, the walls are ready to size!
Traditionally, size is a glue-based liquid made from melted-down horses hoofs. It prevents plaster from sucking the moisture straight out the wallpaper paste. (If paper dries too quickly, or unevenly you get bubbles and stretches and creases.)
The modern way of sizing is to prepare a runny mix of paste, roll the wall area and brush in around the edges. You’ll see the filler darken when you apply the paste. This is good because the filler is absorbing the paste now, and won’t be able to suck the paste off the back of the wallpaper later.
I don’t subscribe to the traditional or the conventional modern method of sizing. Primer sealer is the way to go!
In my experience, play safe when dealing with older properties. There have been so many experiments conducted over the decades by previous tradesmen and homeowners, that it is increasingly difficult to tell what you are actually being asked to wallpaper over.
Unless you have access to the sort of equipment and analytical skills of companies like Patrick Baty, I think it makes sense to use a product that is more sophisticated than glue size or watered-down paste.
You want a sealer that, unlike diluted paste or glue, lays down a barrier over what has gone before, and actively prevents lifting joints / split seams and bubbles from occurring on any interior plaster-type surface.
The Beeline Primer Sealer way
To anticipate any potential problems, prior to wallpapering, I use Beeline Primer Sealer on all plaster surfaces. It is a wonderful product that smells like PVA glue but isn’t! It seals, evens out surface porosity, aids slip and slide when papering – but most importantly, it does what PVA or glue size can’t…
Beeline binds down any poorly adhering filler and prevents the impending paste on the back of the wallpaper from penetrating that filler, softening it up, loosening the bond on the substrate – making it prone to lifting it when it dries out.
This is a checklist for the whole process of How to prepare walls before wallpapering. Stripping wallpaper and preparing for re-papering / lining / lining and painting.
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12 comments to “How to prepare walls before wallpapering”
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What a brilliant, informative guide. Thank you so much for taking the time to write this: I am truly enlightened!
We used to size the dry walls before putting on the paper and glue. Now Lowes tells me I should buy the glue and sizer all in a five gallon bucket and do in one pass. Do you agree with this method? Jerry
I can understand sealer and primer properties in one product, but reduce the porosity of the surface and make the paper stick at the same time. Not sure I get it.
Whot ratio to water do you thin the wallpaper paste to size the wall?
I am using Haraquin paste.
I don’t size with thinned down paste for the reasons of belt n braces / cover all the bases, with a product like Beeline Primer Sealer.
The basic premise of diluted paste is to satisfy the porosity of the plaster, so it really is a case of keep adding water to your base stock until it is the consistency that doesn’t leave a globby layer of paste on the surface you are working with. Bit vague I know, but it isn’t a science and I don’t subscribe to that approach because of the potential inconsistencies.
A few years ago, water came through the ceiling of the house and onto the ceiling wallpaper. This caused parts of the wallpaper to sag down and to bubble. I re-pasted the effected areas with normal wallpaper paste and smoothed it out and that seemed to do the trick. However, last month the house was unoccupied for a few weeks. When I returned, the same affected area of ceiling paper was hanging off again. Presumably the fact it was cold and no heating was on in the room caused this problem. But short of replacing the strip of ceiling paper completely, can I stick the area paper on again, only this time so that it stays on next time I leave the house unoccupied?
Would you recommend undercoating walls in a colour matched to the background colour of the wall paper, then sealing the emulsion prior to hanging. I am papering a large area and concerned the plumb will go out, exposing potential gaps to bare plaster. A manufacturer has recommended this but I’ve yet to try it. Any thoughts. Many thanks.
That is perfectly acceptable practice, as long as you take basic precautions
a) the surface is solid before emulsioning.
b) Make sure the paint is thoroughly dry.
c) By sealing you mean sizing the new emulsion with wallpaper product, and not some sort of wall varnish.
Ordinarily with spirit level or laser these days, you can strike a good line so paper won’t go out of plumb on long lengths, unless the wall goes in and out like a donkey’s hind legs, in which case you could get gaps and overlaps. The approach you are trying tends to cover the eventuality where the paper shrinks “wrong” when hung correctly. Hope that helps.
I have started to remove wallpaper from a ceiling in the house. Most rooms have had the ceilings papered. I have found underneath the thick and several times painted paper … what appears to be a brushed on substance that is mustard coloured! I cannot remove this, but in a couple of tiny patches I can see the original white ceiling underneath.
Any idea what this can be and how to remove it. I’m assuming it’s been on there for maybe 20++ years.
What is the best Polyvine to use for the wallpaper which I am going to use to decorate my bathroom.Need a good damp proof top coat.
Thank you very much,
What is the wallpaper you are going to use? Washables and vinyls are already coated as part of the manufacturing process.