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How to Fix Cracks in Old Walls before Painting

Learn how to fix cracks in old walls before painting from Brushed Interiors founder David Sartori in this Howcast video.


We've got a new your character here. This wall has been the ages of time, you can fill the history. We've got some sample colors on here but looking closely at these cracks and we have got to handle these cracks. The screen color is what is finally chosen for the wall and it'll show up any imperfections so we've got to take a close look here.

It looks like these here are imperfections in an old paint job. It sounds solid. I can get away with simply standing with a rough sandpaper these imperfections smoothing them out without having to break open the wall, but a real concern over here. I'm real concerned over here. And I'm going to the wall and listen for any hollow spots and any and the sounds which is going to be a crack that we have to open up because new paint is going to adhere and that's going to open up anyway. That's a little bit hollow. That is hollow so we've got some really rough spots here. I'm using a stronger more industrial knife and we're going to break this open. Right along the crack, I'm not digging in extraordinarily deep using a couple of different angles. So that's that spot now...

Now I've always got my 5 in 1 handy. My 5 in 1 multi tool scraper and I can use the edge to open this up and sort of round off the edges there. You want to let those cracks breathe. At this point I could put the street compound as a lot of people do landlords and what not, but I like to seal the about. Something I always have on a paint job is bin primer. It's outlawed based, very strong and covers almost anything and it has a lot of uses. So we're going to open up this bin. This stuff is awesome. You have to be a little dainty with though. This will not wash off anything. A brand-new can will tend to trip a little bit, that's all right. This is a throwaway brush also and this is not my nice expensive brush. That's going to fill that up very nicely. I'll catch those drips in just a second. Bin primer, never go without it. Now, as I said some of these other spots can be sanded down. I'll be going through this whole wall and sanding down other spots and smoothing things out and that bin primer dries very fast, that's going to be ready in about 10 minutes. We're going to put our compound and smooth it out. Alright. Our bin primer is all dried so we're going to do out first coat of compound mix.

Now take a look, I've got this standard plaster repairers and joint compound, my mixing mud pan and my mud knives and a little bit of tap water. You'll see a lot of contractors have these on job sites and it's pretty simple. He can do this yourself. Take your joint compound, put it in the mud pan, and plaster repairers is a hardening agent. It comes in a powder and you might put a third or a quarter of plaster repairers into your joint compound and we'll just touch it with water. And we're just going to mix that up. The plaster repairers is simply used as a hardening agent on a deeper first coat of a patch to prevent cracking... Let's put this on, I'll take my wider knife.

This is just the first coat. That's going to dry and think in a little bit. That's totally okay. I'll get a little bit more in there. In other words now for simplicity sake we can just use pure joint compound to repair a wider area of the wall. As long as it's not real thick or deep pure joint compound is absolutely fine and I'll take my wider mud knife. - If you get comfortable with the balance of these really you can do this and you should. You can bring an old apartment back to life. Now of course I'm used to it but you get familiar with the tool and you might hold a finger or two fingers as a balancing and pressure behind the tool to get a nice even pressure. Allow your compound to completely dry, this could take depending on how thick it is anywhere from an hour to three or four hours.

As you can see here the plaster compound mix is already begun to dry because plaster repairers is a hardening agent and it dries very fast, but we'll give this some time and we're going to come back and sanded nice and smooth and put a second polish code over here to smooth it out and we'll be getting close to finally painting our wall. Now I went ahead and did my second coat of plaster compound mix on these horrible cracks. But that set a few hours and then lightly sand that down until it was smooth, after that simply wipe down my wall and I went ahead and rolled this whole wall with your basic water-based primer because it really need it this whole thing, not just this area. I took my time and went all the way top to bottom so that's it. This wall is ready. This wall is ready for color.

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