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Setting type hot mud won't feather in edges?


gunner666's Avatar
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04-09-15, 07:10 PM   #1  
Setting type hot mud won't feather in edges?

I usually used 'green lid' USG with great results for the first coat but am trying to master hot mud to save time and avoid a hair dryer or heat gun for non-hot mud when in a hurry.
I've done hot mud on the base coat and then green or blue lid USG over that with great results.

Tonight, I tried to use just hot mud for the first and final coat just filling a divot that could have been done with one coat. Applied the mud, let it set somewhat and then sponged it with a drywall sponge that has a regular sponge side and an abrasive side. I tried sponging it at different stages of it drying and with different amounts of water and with both sides of the sponge. No matter what I did, I could not get the edge to feather in and taper into the existing wall, it just removes the whole 1/16" - 1/8" layer and needs a coat of green or blue next to get a good feather. I don't know the exact brand of hot mud but I got it at Lowe's so it should be half decent and they're all probably the same thing anyway. I remember hot mud sponging and possibly sanding poorly like this last time I used it for a base coat but I used green or blue after that and got the feather I wanted.

Anyone have any pointers? Would sanding instead of sponging give a good feather in? If so, I might as well use green lid USG and a heat gun or hair dryer on the base coat because I can sponge a feathered edge on that and avoid a sanding mess. thanks

 
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04-10-15, 03:26 AM   #2  
I prefer to use the Blue Lid although the manufacturer doesn't recommend it for the first coat. I saw a guy in Home Depot with all Blue Lid cans on his cart. He said that he never had a problem with it. I guess that you'll have to sand the setting type. Any of it, takes years to master. I'm there yet either.

 
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04-10-15, 03:34 AM   #3  
By "hot" mud, are you referring to dry setting compound? If so, it isn't designed to be a final coat material. Its consistency as well as quick dry time will make it too rough and will dry too quickly. The green or blue, thinned a little always makes a good subsequent coat for smoothing. You should not have to sand anything but the final coat. If so, you are putting it on too thick.

 
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04-10-15, 03:37 AM   #4  
I was under the impression that setting & drying compounds shouldn't be used together. In other words one on top of the other. Is that true?

 
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04-10-15, 03:38 AM   #5  
I use setting type compound almost exclusively. Multiple thin coats feathered with a 12" knife out further with each coat is my style. I don't sand until after the final coat. Sand paper only, no sponge.

 
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04-10-15, 04:08 AM   #6  
Setting compounds aren't water soluble so they can't be smoothed out with a wet sponge after the mud has set up. Like the others, I prefer to use ready mix j/c for the final coat as it is easier to sand. You can intermix setting compounds and regular j/c. I've even added durabond to j/c that was too thin to thicken it back up on rare occasions.


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04-10-15, 09:00 AM   #7  
I use setting mud exclusively. I do acres of patching. I use a lot of five minute and twenty minute stuff. If misted with water just as it sets it can be troweled down almost as smooth as smooths plaster. To feather edges down to nothing I moisten the material on the wall and burn hard on the joint. Sometimes it is not quite down to nothing. I use a wet cloth and the mister and rub from the joint onto the existing work just after it sets but before it is completely hard. I seldom see my work after it is painted. I think the patches are well nigh invisible.

 
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04-14-15, 10:58 PM   #8  
well, the next day, I WAS able to make a good feathered edge with sandpaper. What it is is like I think I've read before that the product says 5 minute or 20 or 90 minute but that's the time it sets but not necessarily when it can be sanded. It still takes more time to sand.



Still probably won't get you as nice a finish as all purpose or E-Z sand mud but I read lots of people say they do all coats in one day AND sponge to avoid the sanding mess. I sanded and did a coat of green over the hot mud. I might just toy around with some hot mud on scrap drywall and see if I can find a sort of magic timing when it can be sponged because the time saved by using hot mud is void if I have to sand it vs regular premixed that I can sponge and if it's a small patch you can blow dryer it for like 10 mins and it might crack but you can get one or two more coats on and not blow dry the last coat and there will be no crack and then sponge that last coat.

Pulpo, blue lid for base coat is a no no, it's doesn't have the strength of green or hot mud and can crack on tape joints. Because it is lighter, the blue has less glue and thus less strength. Hot mud is the strongest if I'm not mistaken, when talking regular drywall muds, not counting something like a diamond coat or plaster acrylics etc. If you use mesh tape instead of paper, then you really should use hot mud to bed mesh tape to avoid potential cracks.

 
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04-15-15, 03:58 AM   #9  
On repairs where time is of the essence, I'll use Durabond for all the coats but I really prefer for the final coat to be regular j/c [any color lid]. Hot mud has a tendency to 'burn' thru the primer/paint if it doesn't have enough time to cure first [an extra coat of paint will fix it] So usually speeding up the drying time of the final coat doesn't help a lot.

The lightweight [blue lid] mud should not be used for the tape coat although there have been a few times where I have when that was all that was on hand


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04-15-15, 06:15 AM   #10  
marksr, so when you used the blue lid JC for the first coat, you never really had a problem, did you?

 
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04-15-15, 11:46 AM   #11  
The only time I've ever used the lightweight mud for the tape coat was on minor repairs. I don't remember having to go back and fix it at a later date. I've never used the lightweight to tape a whole room or more.


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