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-   -   Do screw heads really need to be mudded with three coats? (http://www.diychatroom.com/f15/do-screw-heads-really-need-mudded-three-coats-6120/)

KUIPORNG 01-26-2007 10:49 AM

Do screw heads really need to be mudded with three coats?
 
When coating screw heads (drywall mudding)... Does contractors really mudded them with three coats? Or base on the fact that they are kind of very easy to conceal (if the screw was set properly)... would it be the case that it should be good enough to give them only 2 coats... or even 1 coat... as I don't really know the reason in terms of physics why we need to coat 3 coats on screw heads... consider there are thousands of screw heads... I would want to skip coating these busters if they are not really required.... I also don't understand why people put in a lot of muds on these screw heads as they are already so flat after one coat....

cibula11 01-26-2007 10:55 AM

I know that even if one coat looks good and sometimes even two, you can get pak marks, where the screwed area looks like divets all over your ceiling. I haven't notice this quite as bad on my walls, but whoever did my ceilings did a horrible job. If you're texturing the area, any imperfections will be less noticeable, but with drywall, taking that extra day to be "perfect" will really pay off in the end. Unfortunately I know that from experience.

Honestly, I would think 2 would be enough. Sometimes after you prime the drywall, you can see imperfections more clearly....then you could go back and fix anything too obvious.

KUIPORNG 01-26-2007 11:07 AM

1. What you described as pak marks, wouldn't it be likely be caused by the fact that the screws was not set properly, i.e. not a little bit beneath the surface of the drywall... rather than how many coats been applied? and if those screws not set properly, besides more coats needed, I believe the area of the mud being applied should also be larger in order to conceal the raised screw heads....

2. Or you mean even the screw heads were set properly (a little bit beneath the surface), if the mud only being applied once, you will see a lot of small 1" x 1" spots all over the walls or ceilings , which cannot be concealed by painting... therefore, need to apply multiple coats to make the 1" x 1" spots become say 3" x 12" mudded area so that you don't feel the spotting effect...

3. none of above


which ways of above best describe the theory?

thanks.

AtlanticWBConst. 01-26-2007 04:35 PM

He's referring to 'dimpling' of the nail or screw heads.

Stick with a minimum of 3 coats. The compound shrinks as it dries.

3 coats ensures proper coverage that will completely fill in the 'dimple' of the screw head and leave no impression on the wall's surface when completed.

Use very good lighting while you coat your sheetrock. This will allow you to see all blemishes, including any small dents in the sheetrock surfaces.
ALOT more drywall/taping blemishes will show up once you prime the walls (white)...

Tip: When sanding: Use a very bright halogen light placed at a side-ways angle so that the light's beam flows across the surface of the wall/ceiling sideways. This shows up so much more than if you shine it directly from the front.
Sideways along the surface reveals shadows and even the smallest issues.

(2 coats on the screw heads might look good, until you do this lighting test that I mentioned, then you will realize that you absolutely need that 3rd coat)

MinConst 01-26-2007 09:33 PM

This possibly explains why professional finishers will run the mud down the length (top to bottom) of the wall where the screws are.

AtlanticWBConst. 01-27-2007 08:42 AM

Quote:

Originally Posted by MinConst (Post 31366)
This possibly explains why professional finishers will run the mud down the length (top to bottom) of the wall where the screws are.

Actually, we do it that way to make the sanding easier. Instead of having to sand down alot of small areas (screws).
By coating it in 'one' long patch....we are able to run the sander up and down in just a few long strokes to get it smooth and right.

KenTheHandyMan 01-27-2007 12:56 PM

Not to mention putting it on like that is actually quicker. Taking one long stroke and wiping up one long stroke is way quicker than 'stroke, wipe, stroke, wipe, stroke, wipe'

The halogen light is a necessary tool for this. Listen to Atlantic. A pretty descent looking wall will all of a sudden turn into the craters of the moon once you put a light on it at an angle. And like he said, it just gets worse after the first coat of primer, so it's best to find and fix as much as possible before that.

This is something you're gonna live with for a long time. Take the extra day to get it right.

AtlanticWBConst. 01-27-2007 03:06 PM

Actually, what I was referring to was not the 'thin' line of compound that is used to speedily do the 1st and 2nd coats of screws vertically, but a 3rd coat that is about about the width of the 6" Taping knife (with the edges smooth)

I know that not everyone does the third coat like that, but we picked this up after seeing it done that way on a commercial job years ago.

Rather than having 3 coats of the narrow line, with several outside 'ridges' to sand down... we coat the 3rd time wider (to cover the 1st two coats)....which creates one smooth surface .... and it sands out much quicker and much smoother.

It's the same concept of how the seams are taped. Each coat is slightly wider than the one before it, to go over the 'outside compound edges'.

If you don't tape it wider with each coat, it builds up, and there is a distinct ridge of compound.

KenTheHandyMan 01-27-2007 03:58 PM

That's what I assumed, it's the way I do it. I hate seeing a paint job and you see these little round 'spots'. My walls almost look like several verticle 'butt joints' after my third coat. But once it's painted, it's a consistently smooth surface.

I don't give it quite that much attention if it will be textured.

KUIPORNG 01-30-2007 10:02 AM

How about those screw heads which were not set properly
 
I know, in theory, those should be screw down a bit to set perfectly, but you know, practically, there are some of those guys got pass away due to too difficult to screw or just being lazy...etc..

say there are 5% of screws not set properly, i.e. they are not 100% underneath the surface of the drywall.... Can we use mudding technique to rectify this situation... I assume the answer is just put in thicker mud and wider coverage... is this the right answer ?

or it is somthing I don't want to hear: "Knock off the existing mud and fix the screw even it means unscrew it and screw a new one..."...

yummy mummy 01-30-2007 10:38 AM

kuiporng
 
Hi Kui****g:

Because soon I will be doing drywall, I am reading all your posts.
How about before mudding the screws, you would go through and hand adjust all the ones that are not perfect?

Is it possible to put in all drywall screws in by hand, so that you can get it just perfect, so the mudding job would be a lot easier?


What is your opinion on that?

KenTheHandyMan 01-30-2007 10:42 AM

Actually, if the screw head is not set properly, you have a couple of problems. One, like you say is that it will stick out and get in the way of the knife. This means more mud and in the world of drywall mud, a sixteenth of an inch is quite a bit. More mud means you will likely see a hump. It will only get worse and definately take more time to deal with than just properly setting the screw. If I 'spinnout' and it doesn't sink past the paper, I put another screw 1 inch away and pull the other one.

The second problem is that if the head wasn't pulled tight enough to set into the paper, it might not have pulled the drywall all the way to the stud and you'll have a gap. That means the wall will move back and forth and eventually you get a popped screwhead, popped through the drywall mud that is.

KenTheHandyMan 01-30-2007 10:43 AM

Actually, when mudding, I carry a screwdriver in my back pocket and just fix any problems as they arise.

KUIPORNG 01-30-2007 10:53 AM

Actually
 
Actually, I do the same, with a hand screwdriver with me when mudding... but... the situation is:

- those not set properly are normally those tiny litle bit due to the fact the screw was not going in at 90 degree... and they are so difficult to screw in by hand... but I guess with a good charge power drill, it should work... I just don't border keep charging those cordless drills as you know power gone faster if it is so forcey...


I am talking about those just very tiny little bit above the surface... not even 1/16 inch I believe... but it border the knife from running smoothly... I am sure you come across those... it can probably be fixed like you said... but I thought it is not a big problem so I didn't fix some of them... I will see if I can revisit them ...


and to answer Yummy Mommy another question, You definitely need a drywall screw gun to get a good screwing job done... in my opinion... hand screwing is too hard... regular screw driver will for sure break many holes ...

KenTheHandyMan 01-30-2007 11:00 AM

They have little tips that you can by for use with a regular drywall screw gun. I personally think they sink a bit too deep, but they work better than, for example, a clutch.

An actual drywall/deck driver is the best and gets the job done fast! It makes other drivers look like sssssslllllooooooowwwwwwwwww motion.


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