# Setting type hot mud won't feather in edges?



## mako1 (Jan 7, 2014)

We use hotmud almost daily.The trick is to not put on to much.Never cared for sponges and we never sand except for the slick coat which we use blue lid for.
We take a 10" knife held at around a 45 degree angle and drag it backwards acrossed the joint applying pressure to the edge.This will take off any excess leaving a flat joint.


----------



## chemman (Apr 2, 2012)

Hot mud sets chemically, a wet sponge isn't going to soften it much if at all. Feather the edges with a drywall knife and use a regular sanding sponge to finish the job.


----------



## gunner666 (Jul 16, 2014)

hot mud can only be sanded and not sponged to feather in nicely?


----------



## chemman (Apr 2, 2012)

Right. Regular mud just dries out, so a wet sponge puts water back into the dry mud, softening it, and allowing the sponge to wipe it away. Hot mud hardens and water will not soften it (it will even setup under water), so a sponge isn't going to have much effect on it. Honestly I've never been able to get the hang of sponging, I just wind up making a mess, so I always use sandpaper. I only use hot mud for filling large holes and gaps between panels, anything needing extra strength. I usually go over the hot mud with green lid and finish sand that.:thumbup:


----------



## Nestor_Kelebay (Jun 17, 2008)

The problem is that you're trying to use a damp sponge to smooth out your joint compound instead of allowing it to dry and then sanding it smooth.

The quality control people at USG, Synko and Domtar test the joint compound they make on a regular basis so that they will be alerted to any problem creeping into the production process. Their joint compounds will work as advertised as long as you use them as prescribed. Using a sponge to smooth joint compound is something they wouldn't test for, because almost no one does that.

Let your joint compound dry normally, then sand it smooth and you should have no difficulties.

Some FREE tips:

1. Slip a green Scotchbrite scouring pad under the sanding screen on your hand sander for more efficient sanding. Sanding screen often clogs up with dust because there's no where for that dust to go. By putting a Scotchbrite scouring pad between your sanding screen and your hand sander tool, the dust passes through the screen and falls out the edges of the Scotchbrite pad. That keeps your screen clean and aggressive.

2. If you're using a joint compound with a chemical set to it, you don't have to wait for the joint compound to dry completely before applying the next coat. Once the chemical set kicks in and the joint compound is too stiff to trowel but too wet to sand, you can scrape the joint compound down with a sharp paint scraper and apply more joint compound over top of what you have.


----------



## kt82 (Jan 28, 2009)

do you find that hot mud sets up faster if you mix it by hand instead of using a drill?


----------



## Nestor_Kelebay (Jun 17, 2008)

> do you find that hot mud sets up faster if you mix it by hand instead of using a drill


No, to tell you the truth, it's seldom that I mix up enough Synko ProSet 90 Lite Sand to be still using it for the full 90 minutes after mixing it before it stiffens up. So, in that respect, I hardly even know I'm using a joint compound with a chemical set.

But, so far as I know, the chemical set time is affected by temperature, but I've never noticed any difference mixing it by hand or with a electric hand mixer blade in an electric drill. You might with the faster joint compounds. So far as I know, you can get some joint compounds that kick in after only 30 minutes. There you'd probably notice the various factors that affect the chemical set time more.


----------



## ToolSeeker (Sep 19, 2012)

Hot mud was never meant to be used as a finish coat. It is hard to sand it can be hard to paint. The trouble with sanding it is the edge, it's hard to feather in and to sand the edge it's very easy to destroy the paper. At best it roughs the paper up around the patch. And this causes problems when painting It also absorbs paint different, and give a different appearance when finished.

Read somewhere else and I totally believe to be true:
To a pro Hot Mud is a god send. To the inexperienced it's sent from the devil.


----------



## gunner666 (Jul 16, 2014)

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.


----------



## ToolSeeker (Sep 19, 2012)

Good Luck with that.


----------



## kt82 (Jan 28, 2009)

any tricks to making the porosity of the new mud blend in with the existing texture?
Oil based primer better than using a latex primer , 2 coats of primer or???.

the patches always stand out with the hot mud


----------



## ToolSeeker (Sep 19, 2012)

kt82 said:


> any tricks to making the porosity of the new mud blend in with the existing texture?
> Oil based primer better than using a latex primer , 2 coats of primer or???.
> 
> the patches always stand out with the hot mud



That's why your supposed to finish coat with pre mixed. It is totally different stuff it's rougher texture when dry. Being totally different compound it absorbs differently so when done it looks different.


----------



## scottktmrider (Jul 1, 2012)

Hot mud is harder to work with than all purpose, that's why you just use it for tape and fill coat cause it will be covered on finish coat with ap.its almost impossible to sand hot mud just knock the ridges off and don't worry about sanding to feathered in .you will be going with a wider coat and covering the edges of the last one


----------

