Home Improvement Tips for Finishing Drywall, Part Three – Bedding, Skimming, and Sanding

Ok now we know the basics of drywall terminology and also how to tape. In this section I will cover coating in all of the tape and actually finishing the job along with sanding.

I would suggest bedding in the corner beads as a next step. This will give you practice with the 8″ knife and start preparing you for the 12. It is actually better to mudd up both sides of the corner bead at the same time, before you start wiping any of the mudd back off. By doing this you are able to keep everything a little cleaner and hopefully not too many blobs of mudd on either side. If there are blobs, as long as they are not extremely larger just leave them, and they can be scraped off later after the mudd has dried. Don’t play with your mudd wipe it on wipe it off. The more times you go over your mudd the more you will wipe off making your wall/bead less than flat looking.

Your outside edge will need to be wiped off first to eliminate large edges, then pull your knife down the bead putting pressure on the outside edge and leaving as much mudd as you can over the bead. If you can see the bead after everything is wiped down either you didn’t leave enough mudd or the bead was put on crooked.

After the mudd has dried you will need to come back and coat it in again with the skim coat, and there is not much difference between the two coats of mudd. If after the skim coat has dried and the wall doesn’t look flat or just doesn’t look so good, you can always coat it in again, but usually two coats are enough to produce a good job. You could even use a larger knife on the skim coat. This will help the looks and even help fill it in better. Here it is going to be a matter of preference.

Now we need to hide the tape and this will be done in two more coats ; the bed coat and the skim coats. They are basically the same except that the bed coat could be considered more important, because with this coat you are filling in everything to try and get it as flat as possible, while with the skim coat you are actually putting a tight coat of mudd over the bed coat in order to have it as smooth as possible. You will need to mix your mudd and could add a little water to thin it slightly, just be careful not to add too much because if you do then you will have more shrinkage, thus more of a chance that everything will show after everything is painted.

Paint is probably a finishers worst enemy. How the first coat of paint is applied will have a lot to do with the finished product, and since I am not a painter I will not tell you how to paint. My suggestion would be to roll the first coat of paint instead of spraying it on, and if you are going to spray it on, have someone coming right behind you with a long nap roller blending everything in. Later I will talk about sanding, but one point right now. when you are sanding there is a very good chance you are going to ruff the drywall and by doing this is what will show up the most when painting. You can of course come back after everything is painted, first coat, and sand any rough spots; which is a good idea in any case.

Ok the order is important but not as important as the taping was, and basically you would follow the same order as taping; but here do the flats first, then the butts, etc. hopefully when you were taping you got a feel for the knives. Now we are going to shock you and have you use that 12″ monster of a knife. This is where having two fingers on the back of the blade is going to be very important; it is all about control when using this knife. You might be saying it doesn’t look so hard, but this is where you can really mess up a job.

After you get the mudd on the flat (try to mudd up at least 8′ of a flat before wiping it back down) you will come back and wipe down both the top edge and the bottom edge while leaving mudd over the bevel of the board where the tape is. You will have to use a constant pressure, and if you use too much you will wipe out too much mudd, and if you use to little there will be too much mudd left on and you will have a lot of sanding.

Probably the best way I can tell you is to have the end of the handle about 3 inches from the wall as you are pulling the knife down the wall. If you do not maintain a constant pressure you will have ripples in your mudd and then more sanding. If you see you are leaving edges while pulling the knife down the wall then you either don’t have enough pressure or the handle of your knife is too close to the wall. The same thing would be if you are leaving voids where the mudd is, just not enough pressure.

If you are leaving an edge on the top and not the bottom then you need to adjust your side to side pressure with the two fingers on the back of the knife, and just the opposite for the bottom. A good job is all about control and don’t try to go too fast. Another thing is to watch the back of the knife more than the front, watch where you have been instead of where you are going. By doing this you should be able to tell where you need to adjust pressure on your knife; experiment! Also if you don’t leave enough mudd over the tape, the wall will not be flat and will show up after you paint. When you do the skim coat, it will help to fill in the flat somewhat , but you are taking a chance on it showing. It is just going to take practice to really understand what I am talking about. Using this 12″ knife can be very awkward; experiment and practice.

Ok you have the flats coated, now you will coat the butt joints. Coating these is going to require you to “BUST OUT” the mudd, and leave enough mudd over the tape to make the wall look flat. So what you will be doing is mudding one side of the tape then add a coat of mudd on the other side making the mudd about 24″ wide instead of 12″ like on the flats. This is another time when technique has a lot to do with how something turns out.

After the mudd is applied you will need to wipe it back down making everything seem flat. If you noticed before you taped the butt joint, it seemed that one side was higher than the other. This is normal and is almost impossible not to have this.

Here again this is where common sense is coming into play. If one side of the joint is very much higher or lower than the other, you will actually need to try and fill in more of the low side to help it look flatter when painted. This is done simply by shifting your mudd over toward the lower side while maintaining mudd over the tape. The tape still has to be covered.

If you have a butt joint where one side is very much lower than the other side, you can even add a third knife width of mudd making it 36″ wide, to try and make it appear as flat as possible. Also at this point you will have a lap mark in the middle of all this mudd, this is normal and can be sanded before the skim coat is applied.

So, what you have done is applied a double width of mudd, then you wiped your outside edges, then wiped down the remaining mudd trying to put just enough pressure on the outside edges so they are left clean but you have left mudd over the tape and everything looks flat.

Next in order would be your corners. Since you are not real experienced I would mudd one side of the corner, let it dry then come back and coat the other side. Try not to leave a lot of mudd over the tape. The main thing you are trying to do is to cover the edge of the tape while filling in any voids in the corner, so you actually don’t have to leave a lot of mudd, like most finishers think they have to do.

After the corners comes the top angle. Here again do one side at a time. Maybe even alternate between the wall side and the ceiling side. By doing this you avoid having to get into too much mudd. After that coat has dried then you will come back and do the other side, getting all the tape coated in without too much excess mudd left anywhere. Here again the order you do things is not real important as long as everything gets coated in.

Ok everything has dried and is time to do the skim coat. I would suggest doing a bit of sanding here to get rid of some of the excess mudd, and like on the butt joints at least sand the middle of them to get rid of the lap mark. Then you are going to coat everything in just like you did for the bed coat. probably the only thing I would usually do different is to coat in the butt joints first then do the flats. Your skim coat should be just that, not too much mudd left on anywhere, that is why it is called a skim coat.

Ok now time for sanding, after everything has dried completely. That is another good point I didn’t mention earlier, everything needs to dry completely before the next coat is applied. Sanding is more or less just that; sand everywhere mudd has been applied, even the nails that should have a total of three coats on them like everything else. When sanding watch where you are sanding and try not to sand too much as to rough up the skin of the drywall. This is a total nightmare at times, like when the first coat of paint, as I mentioned earlier, is applied and you can see where every joint is because the drywall has been roughed up so bad. This can be sanded in between coats of paint to help get rid of it, but the over all job will be better with as little sanding as possible.

That’s about it and I hope I have helped you and didn’t leave out anything real important. Common sense is very important when finishing drywall. Try not to apply too much mudd, that you would have to turn around and take right back off. Experiment, practice, less is sometimes better, pay attention to what you are doing, and use your common sense. Good luck to you!

Leave a Reply

Your email address will not be published. Required fields are marked *


one + = 4