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Is this not the easiest way for a perfect drywall skim coat?

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  #1  
Old 12-15-14, 11:10 PM
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Is this not the easiest way for a perfect drywall skim coat?

Take a square notched grout trowel. Mix up hot mud aka setting type mud aka the powder you mix water with instead of the premixed, use 5 min or 20 min or whatever will set fastest but not too fast for the size of job. Next, coat the whole wall with the notched trowel trying to keep the same angle of the trowel i.e the blade of the trowel is always as close to 45 degrees to the wall. Once that sets in like 10 mins, then just use a regular flat trowel/compound knife to go over and fill in the grooves from the first coat and you have a perfect wall. Will still need a little sanding or possibly just sponging and even possibly a second effortless skilless coat of simply swiping mud over potential shrinkage cracks with a flat trowel/mud knife, but I don't think it's humanly possible to freehand a perfect skim coat especially with glossy paint and when the light hits it just right.

Another idea is find something that's hard plastic or metal like 1/4" wide strips that are only 1/8" thick and 8 feet long to go from ceiling to floor. Use a fast-setting but weak adhesive and fix the strips to the wall vertically every few feet. Then just screed the mud on using a 4 foot darby or something using the strips as a guide like how you screed sand for a paver patio base using 1" pvc. When it dries, pull the strips off the wall (might have to dig out a small section of dried mud from around the strips to get behind it to pull off). Then fill in the spaces the strips were using the first coat of dried mud as a guide.
 
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  #2  
Old 12-16-14, 03:06 AM
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While I've never heard of using a notched trowel to apply joint compound - whatever works
When I was learning how to applying a skim coat I found that skimming smaller areas was more manageable for me [something like a checkerboard pattern and then going back and filling in the blanks]
 
  #3  
Old 12-16-14, 05:32 AM
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I never skim with a setting type compound as it doen't have a long enough pot life even at 20 minutes to skim the wall before it begins to set up. Then it pulls and makes a mess of that section.

From someone who has done flooring (spreading glue for LVT and Carpet) as well as tile (thinset) and has used multiple different size notched trowels I give pause to your idea. What ever material you are spreading with the trowel, the excess will bunch on the trowel (like a snow plow) and eventually, it squirts out the ends. You are left with a perfectly troweled middle and higher ridges on the ends. You can go back and work it, but you will never get it perfect. Glue and thinset do not have to be perfect so we don't give it much cause for concern. On a wall, I'd go nuts.
 
  #4  
Old 12-16-14, 06:40 AM
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I agree the desire is there for some "trick" that will permit a novice to achieve pro results the first time--although at the cost of time or a bit of money that a pro would find unacceptable.
Is there such a trick?

I've lived in old plaster homes and all the walls were certainly not uniformly flat so maybe perfection has never been the goal?
 
  #5  
Old 12-16-14, 11:58 AM
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Just work on manageable sized areas, as your skill level increases, so will the size of the area you can do a good job of skim coating. Thinning the mud slightly helps it to flow better.
 
  #6  
Old 12-16-14, 12:58 PM
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Having plastered many walls and ceilings and having worked with all forms of joint compound I can tell you that the concept of the notched trowel would probably not produce a good result . All joint compound style materials remain "sticky" and liquid too long and do not carry the same property of finish plaster to "draw" into the surface of the basecoat and develop a set in a relatively short time. That delayed set would lead to sagging issues with the joint compounds.

I have built up surfaces with durabond mixed with fine and even coarse sand, depending on the thickness of the build. The sand does give the material better sag resistance but to build up a surface with the method you are proposing is not really necessary if you are just doing a skim to improve surface conditions for a level 5 finish, you don't need to be an 1/8" or thicker as your method would produce.

Nor would your method produce walls of uniform "plane" as the trowel would still be following the underlying surface and mimic whatever irregularities are within that material.

A true plaster "by the book" job calls for developing screeds that are set to a plumb or level plane and basecoat applied to whatever thickness (in reason) is required to get walls and ceilings true to that plane. The vast majority of plaster jobs done DO NOT follow that guideline and are generally a collection of planes that can trick you well enough into thinking that things are true.

Having usually done the more precise method of plastering, I can say that nothing is more pleasing to accomplish or look at than a well plastered room. The completion of a true plane with the basecoat also greatly simplifies the application of the finish coat in that pockets of built up finish material do not have to be given additional time to set up for final troweling.

Again, if you are skim coating for the sake of paint consistency, you do not need to be the thickness you are working toward with the notched trowel concept. There are, I am sure, some good videos on YouTube demonstrating troweling compound in a skillful manner to produce the effect you desire. Working the thinly troweled material with a spray bottle of water or a water brush will help in developing a smooth, dense surface that will perhaps require just a light sanding.

As has been stated, practice, practice, practice.
 
  #7  
Old 12-16-14, 02:34 PM
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"Nor would your method produce walls of uniform "plane" as the trowel would still be following the underlying surface and mimic whatever irregularities are within that material."

true but only if it's that bad, in that case, I'd consider the vertical strips glued to the wall on the least damaged areas. If it's so bad, then freehanding compound you'd have to know anyway to go thicker/thinner in some areas to avoid waves in the wall.

Of course this is all just a cheaper quicker way then ripping out the whole wall(s) or drywalling over the existing wall which would get the best results if the wall is so bad.
 
  #8  
Old 12-16-14, 07:24 PM
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another way would be use a curved trowel, one used for leaving a slight hump over joint paper. Make vertical lines with the curved trowel, the humps will be a bit under 1/8" thick and taper off a the sides. Let dry. Use the fattest part of the hump as a screed guide for the next coat. using a straight (not curved) trowel. IOW, if you have a 4 foot plaster darby, you can make your first vertical application as much as almost 4' apart, but if you have a 14" straight trowel, you'll need to make the first curved vertical lines about 1' apart.
This method would avoid the problems some say the notched trowel would have such as saying if you keep making notched strokes overlapping each other then the excess will cake up out the sides of the trowel and defeat the purpose, although I think I could make it work.
 
  #9  
Old 12-17-14, 01:39 PM
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It's been said that overlapping strokes with the notched trowel will cause oozing out the sides and ruining the grooves on the sides of the trowel, but you can leave a couple inches space between the strokes in the first phase and fill them in with the second coat.

You can tilt the notched trowel as much as you want to make the height thin/ thick as you want.

Only thing is someone said the second coat might soak into the first notched coat (because it's porous and might suck in the moisture) causing it to possibly deform, but maybe that depends on the materials, and maybe even if it does shrink it, you can do a third skilless application of spreading mud straight across giving steady pressure using the existing ridges as the screed guide. Or maybe you can spray/roll something on the notched coat so it makes a barrier to block the first one from soaking the second's moisture but still allowing the mud to stick to said coating.
 
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