# Accidentally used paint instead of primer



## AlphaWolf (Nov 23, 2014)

You should re-prime in my opinion. I do this for a living and had it happen on a job of mine from a worker actually. The problem is, the flat u used primed the surface, but did not seal it. This causes absorption issues. So if you reroll the finish over it now it may look good in 2 coats it may look good after 5. As it just keeps getting sucked in. New walls and mud are like a sponge. Yes if u fill it with enough water (your case flat paint and top coats) eventually it wont hold any more and will lay down and dry like a normal wall. Where as primer sealer (notice not just primer) will seal the wall so nothing absorbs in as much. Another issue with not re-priming is any finish paint you use will be harder than the ceiling flat. This causes what i call peanut butter between toast. So your top coat(toast) is hard and strong. flat paint underneath(peanut butter) Is soft. This can cause issues with peeling, cracking even the top coat wasting off and leaving color on a rag. PVA is not the primer i would use. I use it to spray ceilings to a finish thats about it. PVA tends to leave your top coat with kind of a sticky feeling that can go away fast or even last along time. If you can tell me where your buying your paint from i can probably send you in the right direction. For home owners and DIYs folks like your self i just recommend a high grade paint that acts as a primer sealer its self. Now you can just roll your walls 2 times and be done with it. # if needed. Either way easier than 2 different paint gallons back and forth.


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## mathmonger (Dec 27, 2012)

I don't paint every day, but I've done a few hundred paint jobs. I will put SW SuperPaint right over joint compound. The roller stipple doesn't quite match, but absorption has never been an issue. I never had any complaints. 

Uniform, textured walls that already have a coat of paint? You are more than completely fine to go ahead with the color. 

No offense, but unless you and your buddies happen to be super awesome painters, I think you have bigger things to worry about. 

Why do you need a "group" of friends to paint one room? I think maybe there are too many chefs in the kitchen and that's why this mistake happened in the first place.


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## klaatu (Mar 9, 2015)

If you are intending to use flat paint as your topcoat, and nothing but flat paint in the future for ever and ever, just put a coat of flat paint right over it and you will probably be fine. If you intend to ever, ever, ever put a paint with sheen on as a topcoat, (eggshell, mid-sheen, satin, semigloss, or anything but dead flat) it would save you the potential for big headaches down the line if you put a primer SEALER on it now.


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## Nestor_Kelebay (Jun 17, 2008)

clearwaterp said:


> ...and realized that we had been using the flat ceiling paint instead of the PVA primer I had purchased.


In my opinion, this is basically a "six of one, half a dozen of the other" situation.

The reason why drywall primers call themselves a "Primer/Sealer" is because they perform two functions. A "primer" sticks to the substrate and enhances the ability of the top coat to stick to it. A "sealer" prevents the movement of fluid into or out of the substrate. In a latex primer, both of these jobs are done by huge rocks added to the primer called "extender pigments" that are almost large enough to see with the naked eye.

Extender pigments seal the porous surface of the drywall paper and drywall joint compound by "plugging up" the holes in the porous surface of the paper and compound. That prevents the paint from being absorbed into the drywall paper and joint compound, thereby resulting in a thicker and more uniform coat of paint over the primer.

The extender pigments in the drywall primer also cause the primer to dry to a rough surface. It's the increased surface area of that rough primer that results in improved adhesion of the paint to the primer. That is, the paint sticks equally well to each square inch of primer, but the rough surface of the primer increases the number of square inches the paint has to grip, so you get better "apparent" adhesion.

This is how huge rocks can make a coating both a "primer" and a "sealer".

NOW...

FLAT ceiling paint dries flat because it has huge rocks in it called "extender pigments" that are almost large enough to see with the naked eye.

Primer has more of those rocks, and they're more coarsely ground so they're bigger, but a flat paint will make for a much better primer/sealer than a gloss paint.

If it was me, I'd probably put a coat of paint over your flat ceiling paint ON ONE WALL and see how it looks. Look for a reduction in the gloss level of the paint over drywall joints and drywall screw locations. If you can see a difference in the gloss of the paint over drywall joints and drywall screws, then I'd go over it again with primer. If you don't see any such changes in gloss level, then I'd just go ahead with your top coat of paint.

PS: You don't need to know the rest...

A "micron" is a millionth of a meter, or 1/1000th of a millimeter. The hair on a caucasian head is roughly 100 microns in diameter. The limit of human vision is about 1/5th of that, or 20 microns in diameter. A red blood cell is about 5 microns in diameter, and latex paint resins are about 1/10th of a micron in diameter. The smallest thing in a gallon of latex paint is a black pigment, which is about 1/100th of a micron in diameter. Black pigment is actually soot made by burning natural gas in special furnaces with insufficient oxygen to create copious quantities of soot.

The extender pigments in primers are generally more coarsely ground and there's more of them, but between paints and primers, extender pigments will vary in size from 5 to 40 microns in diameter. There's a good chance that the flat ceiling paint the OP used will have done a pretty good job as a primer/sealer.


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## klaatu (Mar 9, 2015)

I have found particles up to 90 microns in several cans of Behr Marquee and Premium Plus Ultra. Also in Valspar Signature. Pretty bad quality control is the only reason I can come up with. I can't imagine pigments this large being put in these premium paint lines on purpose. This is even prevalent in their sample cans. When they dry after using a 4 mil drawdown bar, they leave a very noticeable and visible texture. I have looked at them using a 10x loupe, and they are obviously not bubbles but hard particles. One of the reasons I can't understand why people flock to Home Depot and Lowe's to buy paint.


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## klaatu (Mar 9, 2015)

klaatu said:


> I have found particles up to 90 microns in several cans of Behr Marquee and Premium Plus Ultra. Also in Valspar Signature. Pretty bad quality control is the only reason I can come up with. I can't imagine pigments this large being put in these premium paint lines on purpose. This is even prevalent in their sample cans. When they dry after using a 4 mil drawdown bar, they leave a very noticeable and visible texture. I have looked at them using a 10x loupe, and they are obviously not bubbles but hard particles. One of the reasons I can't understand why people flock to Home Depot and Lowe's to buy paint.


The amazing part is that I actually found a $700.00 grind gauge on e-bay for $50! Maybe Behr is missing theirs!


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## clearwaterp (Sep 20, 2012)

Thanks of the info. I did not need a "group" of painters to help me......rather it was two good friends that wanted to come hang out and help, and yes I was distracted as I was chatting when I grabbed the bucket of paint instead of the primer. 

Anyways, I suppose I will just roll a good primer over it and paint as normal. I live in the central mountains of Idaho so my paint option is really only Sherwin Williams....no box stores here. I have been using shewin williams PVA primer and Cashmere paint.


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## Jmayspaint (May 4, 2013)

Yeah, you better prime it again if your using Cashmere. It's a fine paint but doesn't have good self priming/sealing qualites. Super Paint or Emearld I wouldn't worry about it, they are both ok on drywal without primer but not Cashmere.


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