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Discussion Starter · #1 ·
I'm currently in the mudding stage and I have finished all of my vertical seams which I am very pleased with. I've since moved on to finishing the soffits and corners using a corner knife. Some of the corners have set without cracking while others have clearly visible cracks running along them. I did put a second coat on these spots and that too has dried with a crack.


The compound I'm using is 'CGC All purpose Light' which has a setting time of approx 24hrs. I'm considering moving to a different product as I find it takes more than 24 to set.


As far as I can tell, my technique for the walls that don't have cracks is the same but I must be doing something wrong for this to happen. Any suggestions?


At this point I'm ready to wave the white flag and call for help, but I've already come so far on my own to surrender now.
 

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I believe the light stuff is for finish or top coat, and the corners are require too much mud and they are shrinking too much and then cracking. I used regular Joint compound for the corners with a corner tool(applied a fair amount of pressure) and final skim coat with the topping compound or I guess this light stuff.
 

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Yes- you should be using joint compound for all your (well) joints. I would recommend ONLY using this and not even using the lighter stuff at all. Make sure you also have your joints all taped out as well. The pros use joint compound if that matters at all to you. Also, just because the pros only put down 3 coats and they are done does not mean someone with a little less experience can expect the same. I recommend that you give a GOOD sanding to the places that have cracked and use the joint compound. Also don’t rush it, use multiple lighter coats and SLOWLY build it up. Takes a bit longer but you will be pleased in the end.
 

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I found the All Purpose Light was great for the 2nd coat on butt joints and the 2nd coat on exterior corners but that was about it. The joint compound worked well for the taping coat and the 3rd. Topping compound is the best thing to use for the finish coat, sometimes I was able to do that in three but usually it took a 4th. It depended on the seam and how well I was able to do the 1st and 2nd coat.


Also, lose the corner tool. That thing is a waste of $10. You want to blend each side of the corner a lot further back than 2". Do one side of each corner with a 10" or larger knife and allow the compound to firm up. Then attack the other side of the corner.
 

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corners often take more than 24hrs to dry depending on conditions. As suggested above the product is probably being applied too heavy per coat but it may also be a taping problem if it is an inside corner or a bead problem if it is an outside corner. Usually shrink cracks do not "bleed through subsequent coats if the previous coat is completely dry. So if it is an inside corner with paper tape and the crack is a perfect straight line then more than likely the tape is not bonded well to the board and nothing short of cutting it out and starting from scratch will fix that. If it is a perfectly straight crack on an outside corner you may need to a a few screws to resecure the bead in place. (No big deal ). If the cracks are sporatic and iregular it is probably a thick coat that has shrunk and will bleed if you dont let it dry completely. If you find yourself waiting for a coat to dry and it holds you up you can purchase setting type joint compound that is rated in minutes of working time. The downside is it comes in powder form and has to be mixed. The upside is we can actually complete a room in one day if need be. I use sandable setting type mud for all but the final coat which is lightweight ready mix. The next day we sand and prime.
 

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Discussion Starter · #6 ·
Thanks for the replies. I'll pick up some Joint Compound and see if that fixes it.


Chris, on the corners that are holding with the corner tool I have gone further from the 2" with a 12" blade and feathered it that way. I tried doing the corners without the tool and while it worked, I found the tool made for a nicer line.


On the vertical joints that I have completed so far, I've only done 2 coats. It looks smooth to me but I haven't primed the walls yet to see if I'll notice the seams once they're covered. Is it possible to get it right in two coats or am I just fooling myself?
 

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Hold a 12" blade across the vertical joint as a straight edge (like you were stabbing the wall) look down on the blade and see if you see light at the center which would indicate a cupped joint. Also see if you can rock the blade left and right which would indicate a hump. After you prime, take a flashlight or a flood light and hold it right up against the wall shining it in a parallel path across the vertical joints. That will reveal any major problems that can be dealt with before finish paint. I finish all tapered joints with three coats sometimes four if semigloss paint is used . The third coat is with a 14 " trowel. Butt or end joints usually take four and end with a 16 inch trowel feathered that far from the joint in both directions. (easily end up with 30 to 32 inch patched area to get them right.)
 

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Mancubus, at least 3 coats. Like is said above feather the 3rd coat out. One thing you dont want to do is skimp on this part of the process. The room is already a mess with dust and your going to have to clean the entire house now anyway so do youself a favor and do one more.
 

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Mancubus, you did use paper tape in the corners, didn't you?
 

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Discussion Starter · #10 ·
Ok, I did the light test and it looks good, but then I did the trowel test and some spots have a slight gap in the middle (probably 1/16) so the seam isn't totally flat. I guess I slap on one more coat for good measure.


Larry, I am using the Fibreglass tape on all my joints except for outside corners where I'm using cornerbead.
 

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The pros use paper tape in inside corners, not mesh. That could be the problem.


If your mudding is still thin enough, you can apply paper (mud/paper/mud/flatten) over the mesh.
 

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I used paper w/ metal reinforcment for all inside and outside corners. I also used lightweight compound for everything. Everythings been solid as rock.
 

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Yes, the USG metal reinforced cornerbead is definitely the BEST advancement for drywall newbies... ever. My interior corners actually turned out pretty nicely thanks to them.
 

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I used the metal on the inside corners and they turned out great. I did do the 24-24-24 (three coats, 24 hour dry time each, light sand between each) but it is still a PIA !!


Texturing is a BIGGER PIA and just plain messy (used a gun) BLUH !!


AcroFlyer:p
 
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