A Coat of Many Layers – Skim Coating Tutorial

Believe me when I say that there isn’t one square inch of the master bathroom that won’t have some kind of joint compound/skim coating on it.  As hard as I tried to get the wallpaper off evenly, and really I DID, and I think it would have been a LOT worse without the removal product I found, the hard truth is that I’m working with old drywall.  Since no sizing was applied to the wallpaper before slapping it on, the builders of my beloved Ugg-Duck made my job really hard.  Really.

But, I’m learning.  Hip hip, hooray.  And what is the purpose of this blog, if not to pass on the knowledge I’ve picked up?  Your frustrated ranting from yours truly lesson for this week is skim coating drywall.

drywall repair skim coat tutorial

 

First of all, we should start by clearing up a myth:  most drywall by itself is not smooth.  When first putting up drywall, you screw it in place, tape the seams, and cover them with joint compound.  But the paper covering the entire sheet of drywall is typically not smooth.  Many brands have a subtle texture like cross hatching, which can create a noticeable difference when you paint over the perfectly smooth seams vs. the sorta textured rest of the drywall.  So, the first lesson here is this:  You need to skim coat drywall if you want a smooth finish.  Now that I’ve gotten up close and personal with my bathroom drywall, I’m learning that the above is definitely true in my case.

Next lesson I’ve learned:  To do it right, you will have to put in the time and effort.  As much as I would like there to be, there is no easy button for this.  While I have turned my skim coat into a post-workday evening project, it took several of those evenings to learn to get it right, to get a rhythm going, and to start seeing finished results.  So remember:  it’s not impossible, but you will have to put in the time to see satisfactory results.  You can’t just slap it on and expect a smooth finish in the end.  You can’t expect the sanding step to take care of all of the loose ends (trust me, the sanding part of four walls is a real pain, and you want to give yourself as smooth of a start as possible to prevent hours of correcting later).  And paint won’t be forgiving of your mistakes.

Tool Selection

Create your smooth finish, and everything after it is easier.  Which brings me to my next tip:  The right tools for this job are key.  The right tools are the difference between getting half of a wall done in two nights versus three in one night.  To do it wrong, you’ll need only a bucket of joint compound (“JC” or “mud” as you’ll see in this post) and a 4″ metal putty knife.  To do it right, you’ll want joint compound, a mud pan, a wet rag, and a much wider knife called a joint knife or taping knife – I chose the 10-incher simply because I’m small, in a small space, and wielding anything larger felt like using a snow shovel – but there are wider versions available at your local Blue or Orange.

tools for skim coat

Tool shopping tips:  All-purpose joint compound is cheap, but I wanted to share a little tip to make things easy for you when shopping at the big box stores.  If you go to the paint aisle (where most people search for wallpaper remover, spackling, and other related materials), you’ll find that there is usually only one brand of joint compound, comes in small containers, and can leave you overwhelmed with all of the other vinyl spackling, interior/exterior compound, “smooth”, “flexible”, “high-performance”, “lightweight”, “fast and final”, BLAH BLAH BLAH types around it.  But if you want to save your money, clear up the confusion, and feel more like a pro (who doesn’t?), walk a few aisles over to where they sell the drywall.  Here you’ll find contractor-sized buckets of lightweight joint compound – simple, plainly labeled, and surprisingly cheaper.  You’ll also find taping knives in every size, sanding tools (sanding screens last longer and are a little quicker for a project like this rather than the traditional paper), and a mud pan (a plastic or metal trough-like container that makes using a large taping knife easier when trying to scoop up mud).

Pre-priming

UPDATE:  I’ve now done this skim coat thing a number of times in the house, and a good tip I learned later from a contractor is this:  use an oil-based primer prior to adding your first skim coat.  After peeling the paper off in my dining room, I noticed that the first skim coat would sometimes bubble slightly when the paper layer was weak or peeling (and although you can spend hours removing each peeling piece, it’s impossible to eliminate this possibility 100%).  By applying an oil-based primer, you’re essentially hardening the layer beneath.  This will help minimize (or even eliminate) the chance of any peeling paper from bubbling up in your skim coat job.  Good tip!

Skim Coating

Okay, so now that you’ve got the right tools for the job, it’s time to get to work.  Since even lightweight joint compound needs to be thinned out a bit for skim coating work, you might want to stir in thin texture compound if you have some.  Since you probably won’t, and I didn’t, I suggest using the free version:  water.  Scoop some compound into the mud pan, and start adding water a little bit at a time, mix, then add a little more.

mixing joint compound

It’s easy to think you’re adding enough and then be left with soup, which means adding more compound, more water, etc. until you get it right.  You’ll eventually want it to be about the consistency of thin pancake mix; if you find yourself thinking “oh, that must be why it’s called mud and not paste“, stop.  You’ve reached the right compound-to-water ratio.

mixing joint compound

Next, turn on your radio or set up some kind of music (like my playlist), because this is going to take a while.  Starting at the top right corner of your wall, scoop some mud onto your knife (just a little across the entire blade will do).

skim coat tutorial

At an angle, press the knife against and down the wall, leaving a thin layer of compound on the drywall.  You’ll want to scrape the knife across the wall in such a way as to leave a little of the mud behind, filling in the ridges and gouges while skimming over the entire surface. (*Note:  some of these photos have been darkened to enhance the difference between the wet mud and wall – it’s hard to see off-white on white*)

skim coat tutorial

skim coat tutorial

Then wipe off the knife on the side of the mud pan, and using the same motion as before, scrape the excess mud from the wall.

skim coat tutorial

skim coat tutorial

It will take some practice, but with a steady hand, you’ll get the hang of it in just a few passes.  And don’t be afraid to go over the same spot if you don’t like your first pass; the mud is thin and wet, so it’s forgiving until it begins to dry.  But if you find that you really liked your first/second/third try if it weren’t for thatlittlemistakethere, stop.  Little imperfections can be taken care of in a second pass once the first is dry and sanded.  If you start to see the blade of the knife get gunky even after scraping the excess off, use a wet rag to wipe clean and begin again.

You’ll want to continue doing this across the wall, but since the mud is impressionable until it cures, be careful not to overlap the edges of your various passes across the same wall or else find yourself working to fix a patch of wall you were already done with.  You will be working on this for multiple nights, so it doesn’t have to be covered all at once.  If it’s smoother looking than before you began your work, you’re on the right track!

Sanding

before sanding walls

After you are satisfied with the skim coat and it has had time to dry, the next task is to sand.  Wear a breathing mask and protective eyewear; and maybe a hat – dust will be everwhere.  If you’re going to be doing skim coats in several rooms like I am, consider investing in sanding screens instead of traditional wallpaper.  The sanding screens last longer and do not clog like traditional sandpaper, and also come in 220 grit to give your walls a smooth finish.  The screens attach to either hand or pole sanders, and you can also buy kits that attach to standard shop vacs to keep the dust level down.  I chose a hand/pole combo sander so that I have the option to use a pole extension for the ceiling areas, and also a comfortable and controllable grip to get the areas closer to the floor.  I’ve tested it out in various places on the wall, and so far it’s miles above traditional sandpaper or blocks.

sanding walls

UPDATE:  If you would like a helping hand with the dust, you can also purchase a drywall hand sander kit (most also come with a connection that allows for pole attachment).  These kits come with a connection hose that allows you to hook up the sander to a shop vac, eliminating about 90-95% of the dust that you will experience.  I freaking LOVE mine; it’s so much more convenient and cost less than $25 (you can rent professional drywall sanders too, but they are a bit more of a hit to your wallet).  Just be sure to also purchase the HEPA filters and bags to protect your shop vac from the fine dust.

In addition to the right tools, you’ll also need the right lighting to do a proper sanding job.  The better the lighting, the easier it will be to see areas where you have missed, scratches and pock marks on the wall, areas that are uneven, etc.  If you find such an area, you can easily take a normal putty knife and fill in gaps with extra mud or sand down ridges.  Try to fill in spots as smooth as possible to avoid having to re-sand later (though I did just for good measure).  It’s important to be systematic in your approach; any missed spots will be highlighted once you paint the wall.  Consider using a flashlight in one hand and the sander in the other, moving the light around in different angles to make sure you didn’t miss anything.

Painting

UPDATE:  I tried experimenting with paint and primer combo products, and to be honest, I hate most of them.  I don’t find that they do either job (the paint nor the priming) especially well.  And when it comes to freshly repaired drywall with lots of skim coated areas like these, I find that this is especially true.  Even the nicest paints will have trouble sticking to new mud.  So if you want to keep your walls pristine after all of that hard work, don’t skimp on the last step!  Grab your oil-based primer and use it to seal your walls once more, then paint it with whatever you want.  This will not only help the paint stick, but will also give you a nice, smooth finish to accept your new paint job.

skim coating tutorial - priming

Cleanup Tips

  • Keeping your tools clean and ready for the next job is an important step that should not be missed.  (I realize how much of a hypocrite I am for typing that, but I’m trying to give the right advice here.  100 points to me at least for trying.)  Taping knives are thin and can rust if you leave putty on them – meaning your next project will either have distracting reddish-brown streaks everywhere (increasing the chances of missed spots and ultimately an uglier finish job) or will force you to purchase new tools.
  • I eventually got the hang of timing my evening right so that I wouldn’t have leftover mud, but if you wind up with some on your first day, do not put used mud back into the container.  During your skim coating process, you watered it down, scraped it along a wall with gouges, dirt, and (in my case) tiny bits of paper coming off the wall.  To keep the joint compound in tip-top shape for your next use, just get rid of the left over amount.
  • When rinsing off your tools and cleaning out the mud pan, do not (for emphasis, I’ll repeat, do not) rinse big gobs of joint compound down the sink or tub.  No one likes adding clear clogged drains to their to-do list.  And since you are all aware of how perfect I am (you can’t see it but I’m totally wearing a straight face as I say this), I am merely making a statement for all of you newbs out there – not that I would have any personal experience or anything.
  • For God’s sake, woman, take a shower already.

There you have it – a full skim coating tutorial by a non-professional first timer who lived to tell the tale.  Next up – priming the walls, getting rid of the painted linoleum floor, installing tile, replacing the vanity, and re-grouting the existing shower tile.  No big, right?

Right?

Comments

  1. PF says

    This is useful advice, and will be necessary in a lot of situations. But there are times when smoothing and painting an existing layer of wallpaper is the most expedient rout. If the paper was put up soundly and smoothly, and taking it off will ruin the wall underneath (this can happen with crumbly plaster as well as drywall), it’s easy to simply tape the seams with fiberglass mesh and 2 coats of redi-mix (hot mud for the first coat, if you like), sand and paint it. Then cut out any ripples or bubbles and cover the edges of the cutouts with fiberglass mesh, mud over those, sand and paint the patches. It’s quicker than it sounds because the tape acts as a screed, making the patches smoother than they’d be without it. I did this in my parents house and told the realtor, as well as all potential buyers, all said that it looked fine and had no problem with it. It’s a judgment call, eventually you get a feel for what will work and when.

  2. Audry says

    This website was… how do I say it? Relevant!!
    Finally I’ve found something which helped me.

    Cheers!

  3. Vicky says

    Thanks! I am in the process of removing wallpaper to find ancient, ugly walls that have been wallpapered, painted, and wallpapered again! There is little smooth about them at all. I am disappointed this will not go faster (sigh), but this info definitely helps! I may even try to use a roller in some of the smoother areas. Thanks again!

  4. erin says

    Thank you a million times for your post. We removed wallpaper from our kitchen walls only to find plaster, drywall, and I swear what looked like sandpaper underneath! Your post was extremely helpful and gave me the confidence to do it myself. The walls turned out great, in fact compared to the rest of the walls in my 100+ year old house, they are the nicest! Thank you again, I never would have been able to do it without you!

  5. Spark*Amy says

    Love this! We just bought (well, a year ago) a 1975 house with a glued onto unprimed/painted drywall laminate backsplash in the kitchen and already painted over wallpaper in every bathroom!! I want to rip off that backsplash and hang beadboard wallpaper until I can afford to do tile and new countertops!

  6. Jefferey says

    Hello! I could have sworn I’ve visited your blog before but after looking at a few of the articles I
    realized it’s new to me. Regardless, I’m certainly delighted I
    came across it and I’ll be book-marking it and checking back regularly!

  7. Chris says

    Its good to see you figured it out. In the future you should try a blue top finishing mud, the green top shown in your pic is for taping and is way harder to sand. Because there is glue in it! If you have a good drill get a paddle mixer andmix a whole bucket at one time. Thin it down to how you like to float, about pudding or so. Also try a knock down trowel they are very wide and can spread out and skim coat much quicker. Fixing old work sucks anyway you look at it but it seems you did it your way and came out good. Just trying to help you out next time.

    • says

      I use the blue top stuff now – been a few years since I first posted this tutorial! Thanks for the tip.

  8. Paige says

    Hey,

    I am removing wall paper and a lot of the dry wall underneath is getting gouged. It looks like the dry wall was never taped or skim coated. Also it is nailed up so it would be hard to take off and get new dry wall. Should I tape it and try to make it work or is it too far gone and should replace the dry wall? I’m feeling super frustrated and at a loss with what to do.

    • says

      That’s exactly the same as the situation I was in with my walls. I’m choosing to repair rather than replace, but there really isn’t an “easy” option, as both require some work. A contractor might give you a free quote if you would like to get their input on what you should do.

Trackbacks

  1. […] the walls. We applied a skim coat before priming and painting 2 coats of Sherwin Williams Upward. Here is a great tutorial on skim coating. I really think it was the most important step in the painting process. Wallpaper can hide a […]

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