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Old 05-06-2011, 08:15 AM   #1
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Sanding between coats?


My wife and I are having a disagreement. In finishing the drywall in our master bedroom (a project I've been putting off for a year now) I am convinced we need to sand some of the joints before we put on the second coat of mud. The reason is there are a lot of dips and valleys and rough edges I'd like to knock down prior to messing with a second layer. The wife says we should just sand after we are done. Thoughts?

Also, would three coats of mud be overkill? After the first coat you can still plainly see the tape in some areas.

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Old 05-06-2011, 08:48 AM   #2
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Sanding between coats?


I have to agree with YOU on this one. I ALWAYS sand between coats.
It's the only way I can see what needs to be leveled.
Mud, sand, mud, sand, final mud, sand/sponge = smooth.

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Old 05-06-2011, 08:49 AM   #3
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Sanding between coats?


There are many posts on drywall finishing within this forum, I would suggest a search, but you will and should sand between all coats, to ensure both smoothness and bonding of the next coat, I believe 3 coats of incremental widths is pretty much standard.

A damp sponge on the final coat can help too.

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Old 05-07-2011, 01:20 PM   #4
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Sanding between coats?


I think most professionals do 3 coats too. Although I hear some drywallers do 2 coats with mesh tape but that stuff is good for cracking I hear. I dont usually have to sand much untill 3rd coat 1st I just embed drywall tape and on 2nd I just knock off the knife lines with an old tapeing knife. 3rd coat i apply with 14" tape knife kinda thick sometimes like 1/8 to 3/16" in center, I think this is due to shrinkage or to much presure, cuase I do fill the tapper joint to level on 2nd coat. Sanding creates so much dust that puts silica in the air so I have read, but if you are gonna sand alot I think its best to use a mud with dust control it will not stay in air long like the normal stuff does, but also sandingputs dust on walls that will ball up when you apply mud over it so I'd dust walls with broom and vacuum right after and be sure to wear a dust mask or you will coughing that crap up for a week. If you dont plan to use texture checkout online how to do a level 5 drywall finish it is pretty kewl.
This is my first post I ever did on here hope it was helpful, I just joined today. I am not a professional drywaller, but I am in to construction school I graduate in 1 week and have drywalled like 5 rooms total in my life is all for people I know. Problem i ussualy have is with haveing to do a 4th coat to touch up some places. I would use a quick set but i just dont got the feel of tapeing knife yet. I sanded too good once, the instructor made me refeather the ends.
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Old 05-07-2011, 02:58 PM   #5
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Sanding between coats?


Sometimes I don't sand between the first coat and the second.
The reason for this is that the first coat is seldom anywhere as deep a coat as you will end up needing. So it will always require additional mud.
BUT one thing I do is scrape the walls down with the drywall knife (trowel), blade first like a chisel. The reason for this is the same reason you sand between coats. It is to knock down ridges and humps of dried drywall mud that will cause your knife to bounce, leaving behind even more ridges you'll have to sand later.

I always sand or sponge the second coat... and the third.

The actual overall 'flatness' of your finishing should come from good, smooth, controled use of a wide knife....... not from sanding.
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Old 05-07-2011, 03:00 PM   #6
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Sanding between coats?


I usually wont sand in between the first and second coat.

When applying my first coat however, I don't go too thick, just embed the tape. Simply knock off the ridges with your knife before applying 2nd coat, if you don't go too thick with it you should be able to go right over, filling in the imperfections and feathering it out further than the 1st coat. As mentioned the 1st coat should not be the depth that the mud will end up being, the following coats are too add successively to the mud depth and "feathering it out" wide to hide the joints, especially with butt joints.

Those who are really good at drywall typically don't sand until third coat.

Yes you should do 3 coats, 4 if needed. Often the thing to do is do 3, prime, then you should be able to see what if any touchups are needed.

Trick is IMO is not to go too heavy with each coat. If you apply 1st coat real heavy, then you will need to sand, you are creating more work for yourself than necessary.

Usually I will knock down ridges after first coat, possibly very light sand in some areas, after second coat I will give good light sanding, after third coat I will do a thorough sanding. I will then prime and use a trouble light to ensure a nice smooth finish, if any little imperfections are present I will usually just use a lightweight spackle.

Gives me very good results.

good luck

Last edited by chrisBC; 05-07-2011 at 03:05 PM.
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Old 05-07-2011, 03:13 PM   #7
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Sanding between coats?


Quote:
Originally Posted by Builder2011 View Post
I think most professionals do 3 coats too. Although I hear some drywallers do 2 coats with mesh tape but that stuff is good for cracking I hear.

A mistake I see very commonly with people working on their homes, is using mesh tape with all purpose compound. Mesh tape is meant to be only used with a "setting type" compound, i.e. powdered mud that requires mixing, often referred to as fast set or "hot mud" as I call it at work.

If you use mesh tape with general all-purpose ready made compound, you are taking a chance it will crack.

Myself I only use mesh tape for repair work. I use it with fast set mudd so I can do all my taping and mudding in one day, sand the next day.

When doing larger areas, I use paper tape and all-purpose. Whatever you prefer I guess, however when using mesh tape be aware of products to be used with it.
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Old 05-09-2011, 07:51 PM   #8
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Sanding between coats?


Quote:
Originally Posted by kadetklapp View Post
My wife and I are having a disagreement. In finishing the drywall in our master bedroom (a project I've been putting off for a year now) I am convinced we need to sand some of the joints before we put on the second coat of mud. The reason is there are a lot of dips and valleys and rough edges I'd like to knock down prior to messing with a second layer. The wife says we should just sand after we are done. Thoughts?

Also, would three coats of mud be overkill? After the first coat you can still plainly see the tape in some areas.
Yes, always sand between coats. Also, sand in the same direction that you put the mud on. Each subsequent coat should overlap the prior and no, three coats are not overkill if you are... inexperienced.

The number of coats for a professional is really determined by the material, in the old days we had to do three coats, now adays the material is better and we only do two coats (most jobs). Of course if you have really deep fills you could even put as many as four coats.

Dan - a Professional Drywall Finisher.
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Old 05-09-2011, 07:55 PM   #9
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Sanding between coats?


Quote:
Originally Posted by chrisBC View Post
A mistake I see very commonly with people working on their homes, is using mesh tape with all purpose compound. Mesh tape is meant to be only used with a "setting type" compound, i.e. powdered mud that requires mixing, often referred to as fast set or "hot mud" as I call it at work.

If you use mesh tape with general all-purpose ready made compound, you are taking a chance it will crack.

Myself I only use mesh tape for repair work. I use it with fast set mudd so I can do all my taping and mudding in one day, sand the next day.

When doing larger areas, I use paper tape and all-purpose. Whatever you prefer I guess, however when using mesh tape be aware of products to be used with it.
I disagree. I am a Ticketed Taper, personally I hate mesh tape but there is a purpose for it. The purpose is to speed up a job and skip the taping step. I normally do not work for companies or on jobs where it is used but I do know of several companies who do every job with it. They use All-Purpose for the initial coat.

Maybe were you are the material isn't quite the same. I remember being given mud from back East and it was just garbage.

Dan- nearing 20 years in the trade
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Old 05-09-2011, 11:56 PM   #10
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Sanding between coats?


We do two coat but we had soap to our second coat to get ride out the pin holes. Check it out, but for your topic, lol yea you always sand between coats
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Old 05-10-2011, 03:44 AM   #11
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Sanding between coats?


I don't like mesh tape either and even with hot mud. And I only use it for repairing cracks. You cannot press it in mud and you can spend precious time trying to cram compound through the mesh.

Using a 4-6 drywall knife I apply a layer of mud to the joint. I stretch the paper tape and press it into the mud. I make one slower sweep than usual to remove the excess and leave it alone until the mud sets. It takes practice but there should not be a lot of excess. I gently paper grit sand away the excess to make it smooth anyhow---being careful not to damage the paper. Scarring it will just take more time to skim coat.

Then I switch to much wider knife and skim coat out from the tape joint. The wider knife gives me a longer reference to the surrounding wall. If the wall were not flat an I had not sanded? The blade would ride up and down on the high spots.

As mentioned by a prior poster, I can often get by with one skim coat thanks to modern materials and magic additives like dishwashing liquid---or No Pox if you must pay $12 or whatever ridiculous amount retail for the same.

Just a hint, most DIYs use tools too small for the task at hand for drywall finishing and especially painting. You should really invest in a blade wider than what you used for taping to do your skim coats.

You can gently wet sand your final skim coats with a nice, large car wash sponge by the way unless you left really high or low spots. You should vacuum and wipe the wall before priming anyhow to get as much drywall dust left on the surface as possible.

Good luck.
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Old 05-10-2011, 04:47 PM   #12
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Sanding between coats?


What is this finishing with dish soap??I've never heard of this before?What is the purpose and the ratio???
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Old 05-10-2011, 05:40 PM   #13
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Sanding between coats?


I have a very difficult time with the dish soap suggestions. This isn't the only place it's advised. Some spray painters say to use it too... with latex paint.

But if it is so good for a final finish, why do the explicit CLEANUP instructions on the side of the drywall compound bucket say to, "Wash tools with warm soapy water."? The latex paint manufacturers say the same thing.

Logic seems to dictate that anything designed to be dissolved and washed off with soap sure shouldn't have soap added to it.
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Old 05-10-2011, 09:40 PM   #14
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Sanding between coats?


Yes, adding soap is frowned upon. Just over ten years ago we had problems with one manufacturer of drywall compound. Adding soap helped eliminate pinholes and it helped lubricate the compound so it would roll off the tools easier. However the painters didn't like it as it caused them problems.

I wouldn't add soap with the materials I have available today in my location. It's simply not needed.
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Old 05-11-2011, 11:30 AM   #15
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Sanding between coats?


I only sand the bead after the first coat, and I have used a squirt of lemon Joy detergent in my mud for probably 25 years with no problems or complaints yet....

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