Skimming a Wall

Recently a friend of mine (in the picture) asked me about repairing the walls in a building that he had rented to a small business.   The business in question was a "Christmas" Store.  Evidently their favorite tool was some sort of electric stapler and the walls were peppered with hundred of holes in some places.  Other than this damage the walls were in decent shape.   I recommended to him that he "skim" the wall with drywall compound.   It is a fairly easy process and generally gives good results.  It is not appropriate for walls that have major damage (see the How-To on repairing holes).  You don't need any special tools, just some joint compound, a pan and a wide tape knife (the wider the better).  I've used this procedure with good results over stucco (sand the peaks flat), plaster and drywall.

Where to start skimming the wall?

Where to start skimming the wall?

Level of Difficulty

Time Required:
 4 hours
 
 
Tools:
Large wide drywall knife
Drywall mud pan
Step ladder
Sandpaper
Pliers
Materials:
Drywall compound
Safety Precautions
Observe ladder safety.

Preparation

Before you begin the skimming process you need to prepare the surface.  The surface needs to be free of nails and other debris.  In the process of pulling staples or nails the drywall (especially plaster) will likely "pucker" a little bit.  These puckers need to be sanded flush.  If you are working with plaster, sometimes it will flake; you need to break these flakes off and sand the area.  It is always a good idea to scuff-sand the wall and if you are skimming over gloss or semi-gloss you definitely need to sand a bit.  After you have scuffed the wall, make sure you wipe it down so that it is dust-free.  If the area you are skimming was in a bathroom or kitchen you may need to clean the surface to remove grease or dirt.

Starting the Process

The next step is optional but I find it produces better results.  Thin the joint compound a bit.  Use water to thin the compound, don't thin it until it is soupy, it should still be able to hold a "peak".  Also, put down a drop cloth.

Putting the "mud" on the Wall

Using a smaller scraper or tape knife fill the mud pan about halfway.   Take the large knife and put some mud on it.  Hold the knife at a 45 degree angle to the wall and begin spreading the mud on the wall.

Remove nails

Remove nails

 

Start with mud application

Start with mud application

 

Skimming the Wall (Continued)

Working from one side (I started at the bottom) skim the wall.  The coat that you apply needs to be thin.  It should only just cover the majority of the wall and only gain any depth over the nail holes and gouges.  The easiest way to do this is to lay the compound on thick in one area and "draw" it out of the thick area to cover the surrounding area.  Make sure you leave as few ridges and imperfections as possible; you'll have to sand them out later.  Also, be careful about picking debris up from the wall as you skim.  These debris will create low spots or grooves in your skim coat.  If you find grooves in your skim coat, scrape the junk off of your knife into a spare container.  One other thing to watch for are the bubbles that will form where you cover deeper nail holes.  These will have to be re-skimmed.

Mud application

Mud application

Draw out the heavy sections

Draw out the heavy sections

Carefully skim along moldings

Carefully skim along moldings

Sanding

After you have skimmed the wall, let it dry.  Normally an overnight period will do but if it is humid, it may take longer.  It will definitely take longer if you have a lot of deep nail holes to fill or put the skim coat on too thick.

After the skim coat has dried, it is time to sand.   You can use the sander pictured at left and achieve good, if dusty, results.   You should use a fine sand paper and remove just enough mud to smooth the coat. If you sand through the skim coat it isn't the end of the world, just make sure it doesn't leave lines.  An alternative to the hand sander is an electric sander that is hooked up to a shop vac.  When I skimmed a wall that had a stucco finish this method worked wonders. 

Wall covered in mud

Wall covered in mud

Another coat of mud

Another coat of mud

Round 2

In the course of sanding over the old nail holes you may have uncovered bubbles which developed in the holes.  When you sand the top from these holes you will expose small pock marks in the finish.  These need to be fixed!

Fixing the pocks and sanding

Using a rag, wipe down the skim coat to remove any leftover dust.  Place some mud in the pan and thin it down a bit more.  Using either the large knife or a smaller one, fill in the pock marks.  You might have to work the compound over the holes several times to get rid of any leftover bubbles.  Use more pressure on the knife, if necessary, to force the mud into the holes.  Let this dry and sand these areas again.  Wipe the dust from the wall and get ready to paint!

And more mud

And more mud