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Is it necessary to prime before painting in a bathroom?

My bathroom is being remodeled and the contractor didn't prime the new drywall before painting it. I realize that another coat of paint will cover the pencil markings on the walls, but I'm more concerned about the moisture. Everything I've read indicates that bathroom walls should be primed to protect against moisture.


Will putting another 1-2 coats of paint accomplish the same thing as primer - as far as moisture is concerned or should I insist that they go back with primer before applying another coat of paint?

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Posted 2013-09-13T15:33:54+0000  by KellyO KellyO

Hi there KellyO,


Thanks for joining our community!~


To state it simply, I always recommend applying a primer/sealer on new drywall before painting it. It's good measure and it makes for a much better topcoat afterwards. While there are many options in Paint & Primer-in-on combos out there now, I still like to rely on a separate primer when working with brand new drywall.


So what makes the primer/sealer special? Well most dedicated primers and sealers are referred to as PVA, which stands for Polyvinyl acetate, a rubberized polymer that is actually also commonly found in wood glues and even good old Elmer's glue! It helps to seal the porous surface of the drywall and when it dries, it leaves a surface that the paint prefers to grab on to much more than the drywall paper itself.


Your bare drywall is sort of like a sponge of sorts. It may not look like one, but it sure is! The paper of the drywall, as well as the joint compound used to make repairs, fill screw holes, and bond joints together--they are all sponges too! If you were to apply a coat of just regular wall paint onto them, then they'd have a feast on it and you'd end up with a very thin, thin coat of paint.


Typically what will happen is that you'll apply a coat of paint onto the bare drywall, expecting you'll need to do about two coats tops. But the drywall will absorb your paint, and usually unevenly at that, leaving you with a very thin and very uneven coat. This will then force you to do a second coat, and then a third coat, etc... 


By applying a PVA sealing primer first, you eliminate the need to worry about uneven coats and absorption, and your paint will grab on much better, allowing for a thick first coat that can easily be followed by a quick second coat. 


At the point that you're at now, the PVA style primer wouldn't have as much effect as if it were allowed to be applied directly to the drywall. But I would however still recommend the usage of a stain-blocking primer, such as Kilz 2Bulls Eye 1-2-3 or a two-coat cover of a Paint & Primer combo like BEHR Ultra. My concern would be with how the drywall compound will absorb the paint and at what rate, which could cause for uneven sheen and color. In the future, always make sure the bare drywall is primed when having work like this done.


The ULTRA will be a great choice for you as well because it will give you an antimicrobial, mildew resistant finish on your topcoat, which is great for bathrooms! The satin sheen that I linked you to is a good suggestion for a sheen that works well in high moisture areas like your bathroom as well.


Let us know if there is anything more we can help out with on this and be sure to let us know how it turns out!~

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Posted 2013-09-13T16:23:53+0000  by Jay_HD_CHI

Drywall primers are specifically intended to seal the porous surface of the drywall paper and the mud which bridges the seams. The manufacturers don't have to compromise on making it a stain sealer or giving it great adhesion for going over slick surfaces. It doesn't even have a great amount of pigment. IT JUST SEALS POROUS SURFACES!


As a bonus, a drywall sealer costs less than half of what a premium paint costs. Sure, you could prime the wall with Ultra, but why use such a spendy primer? Further, your finish coat of Ultra will go much farther over  a well sealed wall.


Personally, I feel that the primer is almost more important than the top coat. You will never again have the ability to bond to and seal the drywall. I can relate horror stories where wallpaper was hung over paints that did not have a proper primer under them. A day after hanging the paper, the customers calls and complains that the seams are lifting. Checking out the seams finds the paint stuck to the back of the wallpaper and bare drywall showing on the wall. THE WALLS HAD NEVER BEEN PRIMED! The paint was not bonded to the drywall!


PVA primer is actually not the best sealer/primer for drywall. For a couple bucks more per gallon, 100% acrylic is a far superior  product. This is especially important if a higher sheen finish coat is intended. A coat of semi-gloss will have much higher and much more uniform sheen over acrylic primer than over PVA primer. Such products are Behr's Drywall Sealer or Behr's No.75 All In One Primer Sealer.


In cases where strong colors are to be used, primers can be tinted toward the finish color. However, in most quality new construction, everything is just primed out white and then two coats of the finish paint are applied.

Posted 2013-09-14T02:20:12+0000  by ordjen
Hello KellyO!

In The Paint Department we have a saying, "It's not a crime to prime."

Primer is less expensive than paint and seals the wall ... particularly important on new Sheetrock.

Without primer, the wall will tend to absorb coat after coat of paint; never really sealing the wall.

So, your answer: definitely use a primer before painting new Sheetrock and if you don't, use a paint and primer-in-one.

As your Paint Associate to tint your primer to be similar to the wall color.

There is no charge for tinting and you'll only need one good coat of paint to complete the project.
Posted 2014-11-05T20:42:53+0000  by Pat_HD_ATL
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