As I have stated before in lining paper do you need it I feel people are often too quick to use lining paper. It hinders future maintenance. It is often used to hide flaky paint and bad preparation. (By the way one of the biggest causes of flaky paint on interior paint work is when the paint is applied over wall paper adhesive. What people do is remove paper, to paint but don't remove the glue because they can't see it.)

The Causes of Lumps Under Wall Paper

• filler over nails of other embedded pieces of metal. What happens is as the metal rusts it cracks the filler and pushes it up.
• filler applied over a dusty surface. What happens is the filler pops loose creating a bump
• bad filling which isn't flush
• grit under the paper. A tiny bit of grit can create a large lump. This is often caused as the paper is applied and why it's important to hang paper in a clean environment
• flaky paint lifting
• blown plaster
• cracks opening up and moving
• damp lifting and wrinkling the paper
• paper that has lost or never had adhesion from lack of glue

All these problems can be fixed but only if the surrounding paper is in good condition and has good adhesion. Also if there are many lumps if may be easier and better to just remove all the paper and start again. When I say start again, it should be noted that rehanging lining paper may not be necessary, if the walls are properly repaired.

Removing The Lumps

What this post will focus on is small lumps which are genrally caused by bad filling or debiris.

Cut the paper around the lump with a sharp knife. I like to cut out triangles as it's one less cut than a square. Cut deep ensuring the knife cuts though all the paper. If the plaster feels crumbly under the paper you may need to cut out a bigger section.

Now with a scraper remove the section of paper, now you should see the cause of the problem. If it's blown filler hack it out and remove the dust. You can do this with a dusting brush and/or blow it with a bicycle pump. If there is some rusty metal remove it if you can, if not remove the loose rust and apply two coats of metal primer.

There is a chance that you'll find no obvious cause to the lump. It may have been a bit of grit that fell out with the paper or maybe it's where the paper did't get enough glue when first applied.

Check that the paper on the edges of the cut are properly adheres. If not try cutting out a larger section. If upon subsequence cuts you can't get to adhered paper you should probably remove all the paper from that wall.

Now wet the section repeatedly until it has been wet for about 20 minutes and then remove the glue. You can do this with a green scourer (or what ever colour it may be) or scrape it off. You may find that all this soaking lifts the existing paper but don't worry it should go back down as the paper dries.

When the section is fully dry prime it and about 2 inches of the paper around it. You want to use a primer which is ideally water based and water impermeable. I find the best for this is Zinsser 1-2-3. The reason you prime the section is so that when you fill it, the moisture in the filler wont lift the surrounding paper. Also the edges of the paper can fur up and petrude out from the filler.

Once the primer is dry fill the section. Most general purpose fillers should do the trick but you want one which is quick drying (so not to lift the paper edges) and easy to rub down (so not to damage the paper as you rubdown). Use a filling knife which is larger than the section you are filling. If the section is large you may want to use a chualking tool. Fill in a way that leaves as little to rubdown as possible even if this means you have to second fill.

When the filler is fully dry gently rub it down with a sanding sponge with a fine grit. Once you are satisfied that you have rubbed down all exposed filler hold a torch or lamp sideways along the wall just to make sure.

You may need to second fill but before you do, prime the section again and repeat the filling procedure.

The final procedure is to paint over the filler with the emulsion you intent to use. Thin it down as recommended by the manufacturer for use as a mist coat (a coat which is applied directly over plaster).

Now for one final time shine a light along the wall to check that it is perfectly flush.

That's it! your ready to paint your new flat walls, assuming you have done all the other necessary preparation such as denibbing the wall and washing of any dirt.

When you paint the wall apply the paint thinly to prevent the paint being wet for too long which could cause the paper to bubble up, which could cause problems to your lovely repairs!