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Accidental Painter
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Discussion Starter · #1 ·
So, I am convinced I am doing something wrong with 20 min mud. Been going patch crazy lately.

I noticed when I do a patch w/paper and bucket mud its fine. But every time i use 20 min mudd its a visible hump.

Now i know you do 3 coats w/ 3 blades feathering each coat further out. But it just aint going right with the powder.

I have tried mixing it ultra soupy, & applying it thin as hell. No luck. Seems that third coat is my undoing.

Its not a huge hump, but the trained eye can see it. Any tips?
 

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What kind of bag mud? Durabond will actually expand, I ran some tapers the other day with mesh and durabond then was talking to the drywaller and he told me about it. I got cocky and thought I'd try to get it in two coats and a skim, filled the taper and checked it with my knife perpendicular to the wall, just a hair under. Once it dried, a hair over...:wallbash: Not sure if easysand does the same thing or not.
 

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I am pretty certain that all hot mud expands - but I don't think that the easy sand expands as much as the brown bag.
 

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Accidental Painter
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Discussion Starter · #5 ·
Yeah the second coat is 90% perfect. But theres always a pit or two to fill, so a third coat it gets.

Customer (apartment complex) is just happy it doesnt look like a third grader did it.

Sheetrock 20 min mud.
 

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I don't do tons of patching, but my new habit is to check it with a little flashlight as I apply coats (like when doing a final sand). Sounds silly, but it helps to make sure I don't leave too much, even when the naked eye said it was tight. Easier than too much feathering and sanding.

(Edit: I mostly use "20" & "5"...and paper tape)
 

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master hacker of wood
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Take a piece of rock turn it over , use a square cut a piece the size you need, then cut 2" perimeter around it gently snap the cut line leaving you with a thin piece of paper around the block you cut out!!

Throw in a wood blocker and mud it, once you got it down it goes quick!! Scrape the paper clean carefully
 

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Pro
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FRAME2FINISH said:
Take a piece of rock turn it over , use a square cut a piece the size you need, then cut 2" perimeter around it gently snap the cut line leaving you with a thin piece of paper around the block you cut out!! Throw in a wood blocker and mud it, once you got it down it goes quick!! Scrape the paper clean carefully
Your sir just made a blow out patch . But I don't put blocks in wall . Just mud and go .
 

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master hacker of wood
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If its small nether do I , but if it's bigger I will.

I like it because you don't have to tape 4 times, once your good you can cut up several fast and mud them even faster!

I use them when say a door knob breaks thru or someone deleted a box!
 

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Hard to say because I don't know exactly how you're doing your patches. But I usually patch with mesh tape because it's thinner and transitions from the old to the new better than paper. One layer of hot mud, sand, then one layer of cold mud spread out about 12 inches to feather out the hump if there is one. Then sand, and sponge sand carefully where the new mud transitions to the old part of the wall so you don't see a line.
 

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In my experience, the Sheetrock 90 always tends to expand a little. Dura bond expands like crazy though.
 

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If you are using paper tape. Then here is ur problem you cant let the 20 m8n mud get too dry or it doesnt stick. Make it a touch wetter and what ever you don't use in 10 min is no longer sticky anough for the tape to stick.. dont forget it still needs time to dry if u do second coat right away itll pull the moisture from second coat then bubble.


Use durabond 90 sucks to sand. For first coat then any other mudd after
 

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I patch drywall daily with hot mud, 5 and 20. Its extremely easy to hump because it expands and starts setting in your pan. The mud starts to get a little hard and and you still try to roll with it and it humps because you can't pull it as tight.

If needed I'll lightly sand the hump between coats. If its still there I just bust it out until its gone. It's gotta get painted anyway, who cares if its a 2x2 or a 4x4 area.

Mix a little at a time, it might help. And don't over agitate because that makes it set faster.

Like others have said, try using mesh on patches instead of paper. Paper has a hard time bonding to hot mud sometimes and could be adding to the problem.
 

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if you arnt in too much of a hurry and can let things dry overnite try adding some AP to your hotmud mix. I will throw a couple scoops in a bucket while mixing or add a scoop to my pan while mixing. It will take just a lil longer to set but it will bond better and shrink back to a flatter patch. Or you can set your patch deeper than the wall its on and just fill.
 

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if you arnt in too much of a hurry and can let things dry overnite try adding some AP to your hotmud mix. I will throw a couple scoops in a bucket while mixing or add a scoop to my pan while mixing. It will take just a lil longer to set but it will bond better and shrink back to a flatter patch. Or you can set your patch deeper than the wall its on and just fill.
:eek: you rock chris...:clap:
 

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Accidental Painter
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Discussion Starter · #20 ·
Ok, shoulda gave better details on my methodology.

Doorknob holes i use the aluminum sticky patch. No issues there. Faster than your california patch.

My issues Arise on 2' *2' patches. I cut a square in the wall, insert 2 vert backerboards (1 leftside/1 rightside). Then I mount the patch. I'll mix a half pan of hot mudd with cold water. The first coat I call the "slop coat". I'll just slop it on the patch, put on my 2 vertical pieces of tape and drag my knife over them to set the tape. Then I will do the same for the top/bottom pieces of tape. After all tape is set, i cover it with the first coat and let sit overnight.

Day 2: sand, recoat/feather. Paying special attention to thickness so that all is as smooth as possible. This coat should make patch nearly invisible. Dry all day.

Coat 3: sand. Mix mudd runny as possible to fill pits left from sanding. Be careful to only fill pits.

Thats my process. And it works for the most part. Proof:

ForumRunner_20140307_082644.jpg



ForumRunner_20140307_082709.jpg

Seems though if i mix mudds bad things happen. Like hot/bucket/hot
 
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