A Coat of Many Layers — Skim Coating Tutorial — The Ugly Duckling House

A Coat of Many Layers - Skim Coating Tutorial - The Ugly Duckling House

A Coat of Many Layers Skim Coating Tutorial

Believe me when I say that there isnt one square inch of the master bathroom that wont 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 Im 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, Im learning.  Hip hip, hooray.  And what is the purpose of this blog, if not to pass on the knowledge Ive picked up?  Your  frustrated ranting from yours truly  lesson for this week is skim coating drywall .

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 Ive gotten up close and personal with my bathroom drywall, Im learning that the above is definitely true in my case.

Next lesson Ive 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:  its not impossible, but you will have to put in the time to see satisfactory results.  You cant just slap it on and expect a smooth finish in the end.  You cant 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 wont 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. youll need only a bucket of joint compound (JC or mud as youll see in this post) and a 4 metal putty knife.  To do it right. youll 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 Im 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.

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), youll 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 doesnt?), walk a few aisles over to where they sell the drywall.  Here youll find contractor-sized buckets of lightweight joint compound simple, plainly labeled, and surprisingly cheaper.  Youll 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).


UPDATE:  Ive 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, its impossible to eliminate this possibility 100%).  By applying an oil-based primer, youre 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 youve got the right tools for the job, its 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 wont, and I didnt, 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.

Its easy to think youre adding enough and then be left with soup, which means adding more compound, more water, etc. until you get it right.  Youll eventually want it to be about the consistency of thin pancake mix; if you find yourself thinking oh, that must be why its called mud and notpaste , stop.  Youve reached the right compound-to-water ratio.

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).

At an angle, press the knife against and down the wall, leaving a thin layer of compound on the drywall.  Youll 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 its hard to see off-white on white*)

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.

It will take some practice, but with a steady hand, youll get the hang of it in just a few passes.  And dont be afraid to go over the same spot if you dont like your first pass; the mud is thin and wet, so its forgiving until it begins to dry.  But if you find that you really liked your first/second/third try if it werent 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.

Youll 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 doesnt have to be covered all at once.  If its smoother looking than before you began your work, youre on the right track!

A Coat of Many Layers - Skim Coating Tutorial - The Ugly Duckling House


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 youre 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.  Ive tested it out in various places on the wall, and so far its miles above traditional sandpaper or blocks.

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; its 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, youll 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).  Its 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 didnt miss anything.


UPDATE:  I tried experimenting with paint and primer combo products, and to be honest, I hate most of them.  I dont 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, dont 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.

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 Im 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 wouldnt 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, Ill 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 cant see it but Im 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 Gods 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?

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