Sanding prime coat of new drywall - Page 2 - Paint Talk

Westview · 06-28-2015, 01:24 AM

Quote:

Originally Posted by MixMaster

We've been using the Porter Cable Power Sanders for about 15 yrs. We use 90 grit discs, they are 9" and seem to work well. Still hand sand inside corners, ceiling lines, and base and casing edges. When we first started using them it was tough to convert, hard to change from what we were used to. Now I don't think I could pry the power disc sanders away. In reviewing job costing over the years I know we have increased production times and less wear and tear on the body. Makes sanding drywall patches and repairs easier and faster before the rollout.

Justlooked at the pc power sander and they weight 40lb. That seems pretty heavy.

Boco · 06-28-2015, 10:40 AM

Quote:

Originally Posted by Westview

You spray all your wall primer? Wouldn't you spend twice as much on primer?

Yes you would use more primer but not double. Primer is cheap. My labor not so cheap. For quality purposes nothing beats a good spray and backroll on new drywall. Also I don't think PCs weigh 40 pounds.

Jmayspaint · 06-28-2015, 11:24 AM

Quote:

Originally Posted by Boco

Yes you would use more primer but not double. Primer is cheap. My labor not so cheap. For quality purposes nothing beats a good spray and backroll on new drywall. Also I don't think PCs weigh 40 pounds.

Yeah, materials are always cheaper than labor. Sock it to it as fast as you can, while transfer efficiency is a concern, it's trumped by labor almost every time. Certainly when dealing with cheap materials like drywall primer.

I think the 40 pounds probably includes the vacuum as well. No way the sanding wand weighs that much. The PC's are nice to have. We use it often.

Carl · 06-28-2015, 11:40 AM

Maybe I'm strange, but why would you need to sand freshly primed drywall? If you use the correct primers and backroll, it's not rough.

Boco · 06-28-2015, 01:13 PM

Quote:

Originally Posted by Carl

Maybe I'm strange, but why would you need to sand freshly primed drywall? If you use the correct primers and backroll, it's not rough.

Scuffing down the primer gives it tooth to bond with next coat. For a level 4 tape job scuffing helps hide the joint banding caused from a smooth joint compound to a paper surface. Using a decent primer goes without saying.

**Wildbill7145** · 06-28-2015, 01:17 PM

I'd also add that there is always going to be residual dust from the final sanding of the drywall that will get bonded with the primer creating a rough surface.

At least around here, the drywallers usually do all the priming in my experience. They don't always use the best rollers.

Carl · 06-28-2015, 06:59 PM

Quote:

Originally Posted by Boco

Scuffing down the primer gives it tooth to bond with next coat. For a level 4 tape job scuffing helps hide the joint banding caused from a smooth joint compound to a paper surface. Using a decent primer goes without saying.

Okay, but I think you really reaching there. If the transition between mud and paper facing of drywall isn't rough (because the primer was backrolled) pole sanding that transition isn't going to do anything except cause the painter to sweat.

Boco · 06-28-2015, 09:33 PM

Its all fun and games till you get into critical lighting areas with higher sheen paints.

Westview · 06-28-2015, 09:58 PM

[QUOTE=Carl;836794]Maybe I'm strange, but why would you need to sand freshly primed drywall? If you use the correct primers and backroll, it's not rough.[/QUOT
The drywall is always super rough in areas after prime coat, even with a back roll. You have to sand.

06-28-2015, 01:17 PM	#26
Wildbill7145 Moderator Join Date: Apr 2014 Location: Canada Posts: 5,924 Rewards Points: 5,124 Thanks: 3,916 Thanked 4,508 Times in 2,485 Posts My Photos	I'd also add that there is always going to be residual dust from the final sanding of the drywall that will get bonded with the primer creating a rough surface. At least around here, the drywallers usually do all the priming in my experience. They don't always use the best rollers. __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. Last edited by Wildbill7145; 06-28-2015 at 01:24 PM..

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06-28-2015, 11:40 AM	#24
Carl Senior Member Join Date: Jun 2011 Posts: 403 Rewards Points: 334 Thanks: 79 Thanked 384 Times in 187 Posts My Photos	Maybe I'm strange, but why would you need to sand freshly primed drywall? If you use the correct primers and backroll, it's not rough.

06-28-2015, 09:33 PM	#28
Boco Senior Member Join Date: May 2013 Posts: 914 Rewards Points: 1,392 Thanks: 166 Thanked 526 Times in 328 Posts My Photos	Its all fun and games till you get into critical lighting areas with higher sheen paints.

06-28-2015, 09:58 PM	#29
Westview Senior Member Join Date: Jul 2011 Location: Ottawa Posts: 725 Rewards Points: 516 Thanks: 543 Thanked 142 Times in 106 Posts My Photos	[QUOTE=Carl;836794]Maybe I'm strange, but why would you need to sand freshly primed drywall? If you use the correct primers and backroll, it's not rough.[/QUOT The drywall is always super rough in areas after prime coat, even with a back roll. You have to sand.