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Limit54 05-24-2011 08:28 AM

all i see are dark spots and bumps from the mud after i painted...why?
ok so i mudded my wall with all purpose then on top of that I used sheetrock 20....i sanded and a primed and all is see is the spots where i mudded?.

I have done dyrwall like 10 times....most of the time this happens. I'm using new drywall primer and even flat paint.

no matter what I do i always see the spots where i put mud.

how many different coats should i do? what types of mud? how much should I flare out? what type of sand paper?

I thought i knew how to do drywall but now i have to fix this botched job.


RickyBobby 05-24-2011 11:55 AM

"I have done dyrwall like 10 times....most of the time this happens."

What are you actually "mudding" and where do you see these spots? Corners, seams, screw heads???

I am guessing you haven't sanded out enough....especially if you are seeing bumps.

For your final questions, different mud for different applications. You need to be more specific about what you are trying to accomplish.

chrisBC 05-28-2011 05:00 PM

IMO you have your application backwards. In my experience hot mud (your sheetrock 20) is quite hard, if not impossible, so sand to a nice finish. Unless you are real good at finishing drywall I wouldn't attempt to topcoat with it.

Personally I use sheetrock 20 for small jobs, repairs so I can do all my mudding in one day and then sand/prime the next day.

I usually use sheetrock 20 for the first coat, sometimes second coat if it's small and I want to get all my mudding done in one day. However I learned from experience to use all purpose for the topcoat. It will sand much easier to give a nice finish. I've tried using hot mud for a finish coat before and I just can't get it as nice and smooth as with AP, personally.

I find what works for me is to go quite thin with each coat, so sanding is kept to a minimum between coats, feathering out each coat further with each coat. Especiall butt joints.

to fix it I would skimcoat everything with all purpose, thinned out a bit for a nice smooth coverage and fill in all the imperfections. Give it a light sand, have a good look with a light to see if you will need to go over it again, depends how bad your first job is ;)

That's what I would recommend, prefill/tape with your 20 minute however do at least your final coat with a topping compound or AP.

as for how many coats and how much and what sandpaper, honestly if you are that clueless about drywall I would recommend you get some practice with someone who can show you before you attempt to do it by yourself after reading off the internet.

superspeck 06-07-2011 12:44 PM

What ChrisBC said (I use plain green mud for top coat), plus I've recently found that with the new low VOC paints, it's best to start with a PVA Primer for raw drywall.

ccarlisle 06-11-2011 11:32 AM

Holy smoke; you used your way 10 times and most of the time you had dark spots???

Most people would review their procedure immediately; otherwise half the street traffic you see on our streets would be drywallers returning to their botched jobs!

Look, you should know the difference between a setting compound and a joint compound - or give up trying. ANY book on drywall, ANY bbs should have pointed the way (had you taken the time at the beginning) to Drywalling 101 classes way before this. ChrisBC gave his opinion because he's a nice guy, what he actually did is give you facts.

Steve, do us a favour and look up all the answers to your questions about the flaring and the sandpaper. It's not that we don't want to help you out, but you MUST understand the entire process before you even lift another trowel, from start to priming to painting. That is, if you want nice results.

dberladyn 06-12-2011 02:41 PM

Are you using a PRIMER or a SEALER?

New Drywall and Drywall Compound needs to be SEALED. If everything is smooth, I bet that's your problem. Go buy a quality sealer, seal the mud/drywall, then prime the ENTIRE wall sanding between coats. Problem should be solved.

As far as the bumps are concerned you are not feathering the spots good enough. The sandpaper depends on the type of mud used which varies depending on where you live. I could tell you what I use here as a professsional, but if you are 2000 miles away what you have in the stores will be completely different.

Anyways for finish sanding usually you need 150 to 220 grit sandpaper. Again, that depends on the mud used.

ccarlisle 06-12-2011 03:53 PM

back to basics: he used a setting compound on top of a finishing compound. Both dry differently. So he may have trapped the moisture in.:laughing:

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