Jan 25

How To Skim Coat Rough Plaster For Wallpaper Or New Texture

You’ve decided to wallpaper those walls, but what to do about that rough plaster texture? Will skim coat do the job?

In my experience, you have two basic choices. You can put a liner on the wall first (provided the texture is not TOO rough). This mutes the texture and provides a smooth (relatively) surface to glue paper to.

If you are using the services of a professional paperhanger, you will be paying for the liner and the hanger’s time to put it on. On top of the price to hang the paper itself. And a paper with a delicate pattern may still show some of the irregularity.

If you want to save money and prepare the walls yourself, you can smooth them out by skim coating the surfaces with all-purpose drywall joint compound.

This is do-able, if you have time and patience.

The first thing to do if you choose this option is to prep the surface. Remove any scaling paint, powder, dirt, etc. If you have any water stains, I would seal them by brushing on a stain killer, preferably oil based.

If you wash down the walls, clean rinse afterwards to remove any soap or cleanser residues.

I usually go over the surface with a study flat tool to knock off the worst of the rough points, if possible. This may help to reduce the number of coats of mud required.

Now you are ready to go. Know that you will have to apply a minimum of two successive coats of all-purpose compound, or more if the texture is pretty rough.

Tools: a ten or twelve inch broad knife and a mud pan. Or, a plasterer’s hawk and trowel.

There is a proper order to skim coating, to ease your job as much as possible. The key here is to make your strokes all go in the same direction as you do a coat. For the first coat, I like to go all horizontally, starting at the top of the wall and working from corner to corner. Then move down and continue until you have reached the bottom.

After that coat dries, start at the top again and this time go the other way.

Third coat if necessary, repeat whichever direction looks best to do.

At this point, you may get by with a good sanding to smooth out tool marks. If not, do another coat, varying your stroke directions according to your judgement of what works best. The final step is sanding. Medium grit sanding sponges work well here.

Now that you finally have a smooth surface you can live with, be sure to put on a couple of good coats of drywall primer/sealer (PVA) to render the porous surface fit for wallpaper.

You did it! Now that wasn’t too bad, was it?


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