FAQs

Can you give me some tips on bubbling wallpaper, gaps appearing at seams and lifting of the paper?

Hanging most wallpaper including traditional wallpapers such as embossed papers, lining papers or prints is not ‘rocket science’ and a beautiful finish will result so long as a few basic steps are followed. As with any other decoration work investing time in the preparation and using good quality materials will pay dividends in the end.

One of the most common problems encountered when hanging wallpaper is bubbling, shrinkage and lifting, this article is meant to be a practical aid, (rather than an exhaustive technical article) to avoiding the issue or at the very least to understand in all likelihood what has gone wrong. Understanding the basic science of what is happening helps in preventing all the above.

NB; in this article we are referring to traditional wallpapers rather than technically different paste the wall or non-woven wallpapers.

The basic science bit...

The first thing to understand, if you don’t know already of course, is that a traditional paper based wallpaper expands in dimensions when it is pasted (soaked) with adhesive (paste). Typically a 52cm wide wallpaper will expand 6 to 8mm or more (around 5/16 of an inch or more in old money) across its width –which is over 1.5%. It will also expand at a similar rate along its length.

Why does this expansion occur? The paper fibres are a natural cellulose material and they expand when they come into contact with water.

Remember, paper is wood based and we all know wood expands when its wet, most of us will have experienced wooden doors that suddenly don’t open easily in wet weather for example.

The second thing to keep in mind, again, if you didn’t know already, is that it takes time for the paper to expand fully – generally the thicker the paper, the longer the soaking time – depending on the wallpaper type you will see soaking times between 6 minutes and 15 or even 20 minutes.

So the first important rule then; when hanging traditional wallpaper is to let it soak for the correct time – in our opinion the very minimum time should be as stated on the label and as a general rule a little longer is better than not enough time.

So why are we droning on about this? because Bubbling occurs because of inadequate soaking time…

The simple point is if the paper is not allowed to expand fully on the paste table then it will carry on expanding on the wall – the classic cause of bubbling wallpaper. If the bubbling is not excessive then it may go flat as it dries out when the paper shrinks in the areas that have bubbled…

So what about Gaps and Shrinkage at Seams?

This is the reverse of expansion issue we have already talked about above; If paper expands when wet then it will want to shrink when it is drying…

This is why the wall preparation and the quality of paste you are using is so important because the paste doesn’t simply bond the paper to the wall but its job is also to permanently hold the wallpaper in its expanded state whilst the paper and wall dries out.

What about the surface the Wallpaper is being applied to?

The first thing to consider is the condition of the wall.

For a start it may well be ‘OK to go’, especially if the plasterwork has old paint on it and there is nothing flaking or loose material. The perfect surface is a slightly absorbent one – too absorbent and it will suck all the water out the paste and weaken/compromise the bond, not absorbent enough and the paste may not be able to bond and grip the wall…

So does the wall need sealing or sizing? Try the ‘flick test’ to give a good indication; flick some water from a saucer at the wall – if it soaks into the wall it needs sizing – if it runs down the wall it doesn’t.

So the water soaked into the wall and it needs sizing, what do I do next? We recommend a PVA based size diluted to the manufacturer’s instructions and painted onto the porous area. On a molecular level PVA is smaller than starch based sizes so gets deeper into the wall for a better job.

Don’t go over the top and put so much PVA on that it forms a skin on the wall – this could lead to bonding issues.

It is important not to go over the top or you could end up with a totally non-absorbent surface that is not compatible with the paste you are using and this will result in a weakened bond or no bond at all.

Non porous smooth surfaces will need a light sanding to form a ‘key’ and stability for the paste to bond to.

Paste and paste application;

Once the wall is prepared you are ready to hang the paper – remember to soak it as described earlier and then use a paste of suitable quality;

If the manufacturer is recommending a good quality ready mixed paste – don’t ignore it as the reason will be they believe the superior adhesion characteristics of a good quality paste are required and these qualities are more commonly found in Ready Mixed Pastes; A good ready mixed normally contains higher quality ingredients such as PVA for example. Ready mixed pastes also have a much higher percentage of bonding agents in than flake types, around 20% for ready mixed and only 4 or 5% for flake type pastes.

Use the paste to the instructions recommended – typically for example you will need at least a kilo of ready mixed paste per standard roll.

So, how do I prevent Gaps and shrinkage occurring?

As we have explained, paper expands when soaked and it naturally wants to shrink back to its original dimensions as it dries. The paste’s job is to hold the paper in its expanded state as the paper and paste dries and stop it shrinking back - not just simply to stick the paper to the wall. The bond has to be strong enough to do this and a cheap paste or one past its ‘use by’ date may not be good enough to do this whatever it says on the packaging.

If the paste doesn’t do its job, either because it is not suitable or because of wall preparation, or both, then the paper will shrink and you will see gaps opening up at the seams as the paste loses its fight against the paper wanting to shrink – in really bad cases the paper will lift off completely towards the edges.

So why does the lifting only occur at or close to the Seams?

When the paper wants to shrink, the maximum tension is at the furthest distance from the centre point of the sheet of paper. At the centre point there is no tension and as you move further out towards the edge the shrink tension increases.

Drying times and drying conditions

Always allow plenty of time for the wallpaper to dry out especially when the surface is going to be painted or overhung with decorative wallpaper – as with our products. The manufacturer’s instructions will offer guidance but conditions vary greatly so the drying times will inevitably vary.

Never try to speed up the process by advancing the drying process – such as turning the heating up in the room. This can result in the paper drying much more quickly than the paste behind meaning the paste does not have the time to bond the paper in its expanded state before it shrinks too quickly with the heat being applied – the result will again be lifting and shrinking

All the above is especially important when the surface is going to be painted or overhung with a decorative product – as is the case of most of our Wallpapers.

For example, most modern paints are ‘water based’ so when the paint is applied to the surface of the wallpaper the paper will try to expand – if the bond is fully cured and as strong as it should be, the surface will not be able to expand and a very satisfactory finish will be the result. But if the bond strength is inadequate then once again lifting, especially at seams will result.

Please note the paint will not penetrate all the way through the paper and be able to weaken the paste bond directly – the paint can only cause shrinking if the bond with the wall is too weak.

Conclusion

We want you to enjoy using our products but if that’s not possible at least for you to enjoy the results and following a few basic rules will we hope ensure this.

The old saying ‘don’t spoil the ship for a ha’porth of tar’ holds true in this case…

I have a newly skimmed wall that has a hair-line crack. Will Vellum be a good choice to cover this? Also, what is the difference between Vellum and Papyrus?

Vellum or Papyrus would be great choice to cover this problem, they are made from paper and polyester fibres so they are very strong, and cover these cracks very well. Vellum and Papyrus will also reduce the chance of the crack reappearing as they both move with your wall, reinforcing the surface. We produce Papyrus at 55cm wide and Vellum in both 75cm and 100cm width – the difference is quite simply the width of the roll. As the products are all the exact same material, they can be used next to one another and you can choose the right size for a particular wall.

Do I need to size my wall before hanging Silk Ground?

We always recommend that walls are sized (where necessary) you can check to see if you need to size, by flicking water onto the wall surface. If the water runs down your wall, there is no need to size; however, if the water soaks in then sizing is necessary. There are many sizes available on the market, and we would recommend that you follow the manufacturer’s instructions very carefully.

I purchased one of your Luxury Textured Vinyl papers. It is on the wall and ready to paint. Some people on the web used a primer first on their paintable wallpaper. Do you recommend a primer?

The use of primer may or may not be necessary, but if you wish to create a specific paint effect or technique, then a primer may be necessary. The important thing is to ensure that the primer is compatible with the paper you have hung. The majority of consumers wish to paint with no additional effect, and in this case using standard emulsion, making sure all the relief is covered is the normal method. We would recommend 2 coats, with the first coat being thinned by 5 – 10% with water.

I have some really bad textured walls in my house and Thermal liner will be a good way to get back to flat walls as well as making the room more comfortable and saving energy in the longer term. Do I need to take special precautions when applying Thermal liner over such poor surfaces?

Not really, just make sure the walls are clean dry and solid. If the texture is very deep as with some decorative plaster effects it is advisable to sand down the high points and use extra adhesive to help level the surface. Before sanding or scraping any textured surfaces, we always recommend that you check to make sure they do not contain asbestos or other harmful substances. Stand back and take a good look after hanging the first drop to make sure the result is satisfactory.

Hi, I’ve just bought some of your Wallrock Thermal Liner and was wondering if it was possible to bend it round corners, also what is the best way to cut this product?

We wouldn’t recommend trying to bend the thermal liner round corners, this is because the product is 3 mm thick and very strong, always cut the product into corners using a good quality sharp knife or sharp scissors. When making vertical cuts, mark the liner accurately with a decorators pencil and cut with a saw like motion, this will help you to maintain accurate straight cuts, alternatively good quality sharp decorators scissors can be used to good effect and many people feel like they have more control and confidence, although it is very important to mark the liner correctly to avoid excessive cutting, it’s always better to cut away too little than too much.

I put up Wallrock Thermal Liner and I’m still getting patches of mould appearing – Why?

Wallrock Thermal Liner ‘combats’ mould by alleviating the moist conditions which mould spores need to grow – namely condensation. How? By trapping warm room air at the wall surface and evening out any dramatic differences between the wall and air temperature. A good way to think of this is similar to how condensation forms on the outside of a glass of cool drink on a summers day.

So if you are using this product to help combat mould, it is important to remember that damp and subsequent mould problems can also be caused by penetrating damp from outside or in ground floor rooms by rising damp. As a general rule, condensation problems such as mould often manifest themselves in the coldest parts of a room such as in corners and window reveals. So a mould problem in the middle of a wall would most likely be caused by penetrating damp. As such, damp that is only low down on ground floor walls (approx 1 meter or less) may well be rising damp.

Penetrating damp problems are best dealt with at source, by fixing the cause – similarly with rising damp too. Localised problems however can be dealt with by applying a damp barrier behind the thermal liner; these are available as specialist paints and in roll form i.e Anderton 3 in 1 Damp Foil.

However, you should always remember that these products only mask the underlying problem and stop the wall breathing, expert advice is always well worth sorting out if you have any doubt.

Can you please tell me if your products are fire rated?

Many of our products have been subject to fire testing for which we have certificates available; if you would like to enquire about a specific product, please feel free to contact us and we will forward this to you at our earliest convenience.

Hi I’ve recently bought an old Victorian house and I’m told that the old paper on the living room walls is Anaglypta, unfortunately a section has suffered some water damage and instead of striping the whole room I’d prefer to try and match the pattern and replace the damaged area. Can you help?

Hi, we will always try and help people with matching old and existing patterns, the first step is take a few photos that show the pattern clearly in a good light, this will help us to quickly identify the pattern if possible from our archive of old pattern books.

Over the years we have produced many different patterns and unfortunately not all are current and subsequently no longer in production, if we are unable to match the pattern we can always suggest a paper similar in style, size and relief.

I have some wallpaper left from a project that I did last year, and have bought some more of the same pattern. Why are they a different colour?

All our papers are made from responsibly sourced pulp which is a natural product, so very slight variations in whiteness can result from batch to batch as a result. When painting our products with modern paints you will normally find two coats are recommended by the manufacturer to achieve the best results - this will normally also ensure any shade variation is completely eliminated.

I have a hallway and stairs with a dado at 89cm, which of your Dado Panels will be most suitable for this application?

All of our dado panels are 104cm tall, so on straight walls any of the patterns would be suitable and can be trimmed to suit your height of dado rail. For projects that involve a staircase, we would recommend either the Rococo (RD06730) or Oriental (RD06700). These patterns still have 10 panels per roll, but each of them is divided into smaller sub panels, allowing easier hanging on stairs. Click here to see an illustrated hanging example.

I have lined my walls to smooth them out before emulsion painting them and I have noticed that after painting the seams are opening in places. Why is this as I sealed the walls carefully beforehand?

As with any standard wallpaper, lining paper expands when soaked by circa 10mm and wants to shrink to its original dimensions when dry.

So when dry there is in effect inbuilt tension in the paper which is at its maximum at the edge or seam.

So even though the paper was flat before emulsion painting in your case it is likely the water based emulsion has weakened the bond at the seams. Wallpaper contains ‘size’ to prevent it soaking up too much water but at the seams the water can more easily track around the side and weaken the adhesive bond which can lead to lifting at the seams.

The poorer the adhesive quality and the weaker the mix the bigger the risk.

The best way to combat this is to use a good quality adhesive that has more ‘wet tac’ i.e. it remains quite sticky when wet and the bond strength returns after re drying. These characteristics are not found in most dry flake adhesives whereas most ready mixed adhesives do have good ‘wet tac’ properties.

NB; Please see other FAQ’s especially ‘The problem of Bubbling Wallpaper, Gaps appearing at seams and Lifting of the paper’.

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