If you're interested in the back-story behind this project then head on over to my blog for more details, where I also add a discussion of whether this might be the right method for you and give away my incredible secret way to clean brushes effortlessly! For the purposes of this Instructable, it's sufficient to say that I needed a semi-permanent way to make our kitchen walls look better, as the existing knotty pine is a good fit for a Tahoe cabin but not a mid-century modern. I decided to use joint compound (aka "mud") that is normally used for covering the gaps between sheets of sheetrock to fill the gaps between the knotty pine boards, and then paint the walls.
"But I've used Spackle before to cover holes. Can't I just use that?"
No. The existing Sheetrocked wall in the kitchen is new; it was put up when we converted our laundry room and the old eat-in area of the kitchen into a third bedroom. There was a gap about 1/2" wide and an inch deep between the new sheetrock and the old knotty pine in the corner. I didn't want to mud it as the mud would have taken ages to dry and I would have had to do endless coats so I Spackled just that area. Spackle is designed for easy filling of small nail holes, not large expanses that need to look really smooth. I couldn't get the Spackle to properly adhere to the Sheetrock, or get it completely flat, and you can't put a skim coat (top coat) on it to even things out - I guess it's like caulk, which doesn't stick to itself once one layer is dry (yup - learned that one the hard way on a previous project).
Use Spackle to fill small holes in Sheetrock. Use mud to fill gaps between knotty pine boards.
Step 1: Tools & Materials
1. Belt sander with ~50 grit sandpaper
2. Rubber sanding block with 100 or 120 grit sandpaper sheets
3. Joint compound (link to a sample of something that could work; further discussion of types of mud in step 2)
5. Drywall tray (can be plastic as long as it has metal edges for scraping the knife against)
6. Primer, paint, brushes, rollers, and any other painting equipment you normally use
Step 2: Step 1: Prepare Surfaces
- Put up dropcloths to contain dust. Sanding wood is moderately dusty; sanding drywall is awful. And use a face mask; you don't want to breathe this junk. Remove trim - we had some baseboard that had been installed as a 'backsplash,' and I also removed the outlet covers.
- Sand the whole surface. Don't even try doing this by hand; I used my trusty Makita belt sander. Sanding overhead (on a vertical surface) isn't nearly as hard as you might think, as the action of the belt helps the sander 'climb' the wall. Controlling it at the bottom of the wall (when it wants to disappear into the countertop) is much more difficult. I used a pretty rough grit; about 50, I think - but use whatever rough grit paper you have.
- Wipe down the walls to get all the sanding dust off. Don't skip this; dust mixed with mud = uneven surface.
(No photos of this step because I didn't want to get the camera covered in dust, and my husband was keeping our toddler busy well away from the nastiness.)
Step 3: Step 2: Mudding
1. Get your joint compound. I had some of a massive bucket of pre-mixed mud left over from the laundry room project, so that's what I used. It is possible to get powdered compound that you mix with water yourself (not recommended for beginners; too hard to get the consistency right) and also quick-set compound (also not recommended for beginners, as it can start to set up before you've finished getting it on the walls). The regular stuff stakes 24 hours to fully dry, especially in the deep channels between the boards of our project.
2. If you haven't drywalled before, watch this video to see how to use the tools involved. We will not use tape; drywall has dents at the edges to accommodate the thickness of the tape and mud that are used to bridge the gaps between drywall sheets. Knotty pine doesn't have this, and I didn't want to create 'mounds' of tape and mud to cover the tape edges. The most helpful parts of the video are:
- 2:14; loading up the tray with mud;
- 3:10; applying the mud to the wall (notice how flat the putty knife is against the wall);
- 5:15; ignoring the tape, and starting at the top of the wall because you don't have to worry about bubbles in the tape, see how to hold the knife firmly at a 45 degree angle to take off the excess mud both on the channel itself and around the edges, creating a smooth transition between mud and wall.
3. Follow these basic steps from the video to apply and smooth your mud. Your boards will likely not be flat (as mine were not), so use mud to 'build up' the surface of the lower board. Use the narrow putty knife to get the mud on the wall (much easier to manage) and use the wide knife to create the flat surface as you remove the excess mud. Clean your knife between each sweep when you're using the wide knife as any debris (dried mud, sanding dust) that gets caught under the knife will drag across and mar your finished surface. No big deal if it does; just apply more mud and do it again, but better to save yourself the trouble.
4. I was careful to avoid getting any mud on the ceiling, to the point of leaving the very tops of the joints unfilled. We will eventually tear this wall down and I don't want to spend days scraping mud and paint off the ceiling when that happens.
Step 4: Step 3: Wait, Reapply, Evaluate
1. Wait 24 hours, and maybe a bit more. You'll know the mud is dry when it's an even white in color; taupe-colored mud is still wet. Mud shrinks and cracks as it dries when it's applied too thickly, so expect to see cracks down your bead lines. Don't panic (yet), but if you put the second coat on before the first coat is dry the first coat will continue to shrink and crack causing your second coat to shrink and crack as well.
2. Sand off any major imperfections by hand (with your rubber sanding block) using 100 grit sandpaper. Remove any blobs of mud, and anything else sticking up from the surface of the mud. Dry mud sands very easily without much elbow grease, but don't forget your mask.
3. Apply the second coat of mud, getting the mud as smooth as you possibly can both down the channel and also across the surface of the wall (where your boards might not be laid flat). Also put mud on any knots that have cracks in them - press on the mud and then sweep it off with the knife at a 45 degree angle. The mud should fill the crack but leave the rest of the knot's surface clear.
4. Allow to dry.
5. Evaluate whether you need a third coat. If you still see cracking or shrinkage, sand and apply a third coat in the same way.
Step 5: Step 4: Finishing
1. Once all coats are up and dry, use 120 grit sandpaper to do a finish sand. Basically you want the mud to feel completely smooth under your fingers. Feather the edges of the mud so you see the boards through the mud and the mud just fills the scratches left by the first sanding. Try to eliminate any rough or raised spots along the channels between the boards. This is tough to do if you don't have a ton of experience (as I don't) but you can get it reasonably good. Remember that paint will not hide imperfections.
2. Prime. Do not skip this step. The knots in knotty pine contain resin that bleeds through regular paint (ask me how I know this).
I had half a can of Kilz primer left over from another project so I started with that, although I was quite surprised to see how much the boards showed through even after two coats. The primer looked white when it was wet, but the yellow showed through once it was dry. When the Kilz ran out I switched to Zinsser Smart Prime that my husband Alvin had picked up, which stayed more white after each coat was dry. I wanted the walls to be evenly colored before I started to paint as I only had a third of a can of leftover colored paint so I didn't want to have to do a lot of coats with that. I ended up putting four coats of primer on the big wall and five on the window wall, as I had to brush rather than roller on the window wall and it was hard to get the paint on thick enough.
3. Paint. I had to put three coats on the big wall and four on the window wall before all the primer was covered and we could see the true paint color. After the first coat the walls looked lurid as the white primer was still showing through quite a lot. Matte paint hides flaws slightly better than semi-gloss, although semi-gloss is more washable - pick your poison.
Step 6: All Done!
Even my husband agrees it looks pretty good, and usually the first thing he does upon inspecting one of my projects is to point out what's wrong with it. We subsequently added a new faucet, sink, and countertops, and sanded and painted the cabinets - all told we spent about $3,000 for an update that will definitely get us through the next five years or so - until we can afford to tear that big wall right down.
You might note that the newly "Sheetrocked" walls ultimately ended up grey rather than green; once the green was up we decided it really was a bit much (the people who staged our house before we bought it picked the color, and I refused to take all the stuff of the shelving unit to paint the back wall again) so we repainted with a grey that better matched the countertops.
So as to save this Instructable for the actual instructions, I left on my blog a discussion of whether mudding your knotty pine might be the right way to deal with your own decorating challenges, as I don't think it's the best solution for everyone. I also share my tip to save 90% of the time (and 90% of the water!) it takes to clean paint brushes...