[mx13]

I just thinned about 1.5 gallons of all-purpose premix with water to the consistency of cake batter to roll it on a wall and smooth with a 12" knife. This went pretty well, except I have a thousand little bubbles that are going to leave 1/16" holes. I'm never going to get a good surface if this keeps happening.

I used this to mix because I was told that a full-sized paddle mixer would require too much torque for my old drill without a side handle.
https://www.lowes.com/pd/Blue-Hawk-3-25-in-Steel-Spiral-Mixing-Arms/1000239545
Is this not going to work, or do I just need to slow down?

I did notice that when I reversed the rotation of the tool so it pushed itself down in the bucket (and lifted the mud up) that it seemed to incorporate less air, but I was halfway through with mixing at that point. Is that the secret?

 

[ClarenceBauer]

Your drill RPM is to high & the mixing paddle will introduce air into the mixture.
Joint Compound mixing " Power is supplied by a 1/2" heavy-duty electric drill with a speed of MAX. 400 rpm for joint compound 300-600 rpm for texture. Drills that operate at high speeds will whip air bubbles into the mix. rendering it unfit for finish coat purposes."
The above info can be found in the USG Gypsum Construction Handbook.
The best paddle is a cage type , next is Junior Mud Mixer # DC713.
www.KraftTool.com

 

[mx13]

I tried going slower with what I have and that was a total bust. Just some initial manual up and down mixing (drill not turning) already blew a ton of bubbles, so after that keeping the drill speed down didn't seem to matter. The damage was already done.

Neither Lowes, Ace Hardware or Home Depot will admit on their websites to selling the Kraft tool in my area. There's a concrete business a mile from me that is the about the only other place I can think of to ask.

There is this available in my local:
https://www.homedepot.com/p/QEP-Super-Thinset-and-Grout-Mixer-Mixing-Paddle-61205Q/100177456

Is that any better?

 

[jeffnc]

For most drilling operations, you want high speed and low torque (or at least torque doesn't matter much). For mixing things, you want low speed and high torque. Even when mixing something that doesn't get ruined with bubbles, such as thinset, high speed doesn't help since it will just fly crap around. High torque is very important though.


https://www.harborfreight.com/power...-low-speed-spade-handle-drillmixer-56179.html

 

[Colbyt]

For a 1.5 gallon batch I would not use a drill at all. I just mix it by hand with a slotted spoon; a spoon that is now mine because the wife caught me using for this purpose.

 

[dtbingle]

Your wall surface might also be contributing to your problem. From the sounds of it, you're rolling on mud and flattening it out doing a skim coat. I'm assuming your wall is previously painted, or recently sealed up with a problem surface sealer.

From what I understand, if the base layer is sealed with paint or a surface sealer, the air can't permeate into the wall like new drywall, and therefore you get more bubbles on the new finished mud surface. Ran into the problem after using gardz then skim coating in my bathroom. The advice I got here was to basically do a skim coat, then do successive coats over the same area to fill in these bubbles until gone.

 

[jeffnc]

From what I understand, if the base layer is sealed with paint or a surface sealer, the air can't permeate into the wall like new drywall, and therefore you get more bubbles on the new finished mud surface.

Not saying you are wrong necessarily, but my reponse to this is "what air?"

 

[dtbingle]

Not saying you are wrong necessarily, but my reponse to this is "what air?"

Beats me - I'm just regurgitating what I found after experiencing this. This is the best explanation I got haha:

 

[mark sr]

When mixing with a paddle I use a slow speed heavy duty drill. But for repairs I just mix the mud in the pan.

 

[jeffnc]

Beats me - I'm just regurgitating what I found after experiencing this. This is the best explanation I got haha:

https://www.youtube.com/watch?v=EpoRelGiqxY&feature=youtu.be

Looks like he knows what he's doing from a technique point of view, but I'm pretty sure he's wrong about the technical reason it's happening. At the end of the day I suppose it doesn't matter much - if it happens, try his technique.

 

[mx13]

Those bubbles look exactly like what I got in my second coat of thinned premix mud, whether rolled on or applied from a mud pan with a 12" knife. First coats (90' hot mud on one wall, unthinned premix on another) were over drywall sealed with Gardz and neither did that. So, I'm blaming my mixing technique, at least for now.

I love that guy's videos, but, man, he makes it look easier than it is! Also interesting that he mentions shoulder injury. I have some pain from a pinched cervical nerve due to a trapezius strain from lifting, and while not exactly the same, drywall coating isn't doing it any good. Gotta double-down on my physical therapy drills!

 

[LS-6]

Don't add too much water(sounds like you did if you can roll it on)because air can mix in easier when the mud is thin, plus it might crack when drying also.

 

[jeffnc]

Mixing it thin to get it on a roller is actually a good technique for the third coat, or for when skim coating. This is explained in Myron Ferguson's drywall book. Works well and very fast for large areas.

 

[mx13]

Don't add too much water(sounds like you did if you can roll it on)because air can mix in easier when the mud is thin, plus it might crack when drying also.

I've seen multiple recommendations for rolling mud on with a 3/4" to 1" nap roller, and everyone recommends thinning the mud quite a bit. "The thinnest mud, even thinner than for taping," was one quote I think I remember correctly. So I'm assuming this is possible to do without horrible bubbles but that I'm just doing it wrong.

It does let you get some area coated very quickly. If I can just minimize the bubbles, I'm sold.