Drywall Primers vs. Drywall Sealers
Summary: Drywall primers and drywall sealers are very different. The two drywall finishing liquids contain different amounts of resins and fillers. Avoid imperfections in drywall by selecting the correct primer or sealer.
Related Articles: finish problems, drywall decorating, finishing tips
Imperfections in drywall are very common. These imperfections, however, can be traced to a wide variety of causes. Frequently, the cause may be poor or unskilled workmanship. Often the imperfections can be traced to lumber shrinkage. High humidity and large temperature swings during installation and finishing can cause problems. Poor carpentry techniques also can be to blame. However, did you ever think that a problem could arise in the paint that you use?
Resins and Fillers
Paints are a combination of ingredients. No two paints are exactly alike. Chemically speaking, paints are almost identical to adhesives. Paints primarily have three ingredients: Resin, vehicle and pigment.
The resin in a paint is the glue that allows it to stick to a surface. The resins are usually clear and almost always encapsulate or surround each pigment particle.
The vehicle is the ingredient which allows paint to be a liquid in the can. I often refer to it as a temporary ingredient, for once you apply the paint to a surface, the vehicle evaporates into the air. That is why you must ventilate a room when using a paint that contains hydrocarbons or flammable solvents. These liquids turn into a vapor and can either make you sick or, if ignited, explode.
Pigments are the ingredients which impart color. They are solid particles comprised of many ingredients. Without resins, the pigments would not stick to the surface you paint. They would simply wash off. In fact, that is exactly what happens with exterior paints that chalk. The resin which is exposed to the weather breaks down and releases the pigment particles. The pigment then washes down onto your brick, foundation or driveway.
Primers vs. Sealers
Just about everyone who has painted something has heard of primers. Some of us have also heard of sealers. Did you know that there is a big difference? These two foundation paints have entirely different qualities.
Primers are specially formulated paints that are used to smooth out the surface you are painting. They have great filling capabilities. Because they have a high solid (pigment) content, these solids can fill in any microscopic valleys, depressions, etc. Primers are usually low in resin, so that when they dry, the surface of the primer film is coarse . This allows the finish paint an excellent surface to grab onto.
Sealers, on the other hand, are exactly opposite of primers. They have a high resin content and a low solid (pigment) content. Sealers are formulated to regulate the rate of absorption of the finish paint. This quality is achieved by the high resin content. The resin, when dry, creates a barrier. Finish paints cannot easily soak through sealers.
Different materials absorb liquids at different rates. Materials such as these are said to have different porosities. Finish paint which is applied to a surface that has several different porosities will not dry at equal rates. Those areas of the surface which absorb the paint quickly will pull the paint (and paint particles) deeper into the surface. The sheen of the paint will appear uneven, even though the surface which was painted is smooth!
|
|
Comments:
Kurt Flowers 17 Dec 2007, 19:20
Tim,
I have a very serious problem with my walls in my new home. Even as we were moving in 'nail pops' by the hundreds as well as split walls and ceilings throughout the entire house became evident. Time and time again the 'pops' and cracks have been fixed and within one month they, along with others simply return. I literally can see new pops each day that were not there the day before. My bulder will not fix them because they have tried several times and by the time the repairs were finished the pops were returning before their very eyes. One of the workers confided in me and told me this was the worst case he has ever seen in all his years in the business. My bulder as well as my super simply said "I should not worry about it... this happens all of the time and it is natural settling" I don't know what to do! Is ther any solution. I would have to be repairing walls 24/7 and still could not keep up. Please let me know if there is any solution! Thanks
AsktheBuilder 17 Dec 2007, 19:32
Kurt,
It is not normal. Read ALL of my columns about drywall defects. Buy a copy of the Gypsum Construction Handbook as your settlement document to prove if the drywall was installed right.
Rockie 30 May 2008, 00:07
Nail pops in a new home? This should never happen on new drywall EVEN IF
the drywaller actually used NAILS. If he did, someone should point him
(them) to a local hardware store where (yes they do) sell drywall SCREWS.
Of course it was framed REALLY poorly, you might get the odd one, but not
to this extent.
Danielle 19 Jun 2008, 07:50
I just bought a house that has lead paint on the trim. I want to paint the
trim since it is so yucky looking. Can I just prime and then paint so that
I do not have to sand the lead paint or use anymore chemicals in my house?
John B 06 Jul 2008, 10:26
Thanks
bob gudinas 09 Dec 2008, 17:17
the nail or screw popping would seem to indicate to me that the framing
wood was wet/ or at least had a moisture content over 20%
as the wood dries; one might think that the tightening of the cells in the wood would hold the screws or nails tight i'm of the belief that it would push the screws out.
bonnie 30 Dec 2008, 16:40
We had texture paint all over our hallway walls. We stripped the walls and
in the process, damaged some of the drywall. We were able to fix the
problems to an acceptable point (for somewhat amateurs).. My question to
you - if we want to paint the walls, do we seal first, then prime? We
retaped some of the corners and seams and did a lot of mud work and sanding
on the walls. You mentioned the Sheetrock First Coat by USG.. do i just
use this product or do i also use a seal and THEN apply the first coat? We
want to put regular paint on the surface.. thanks for your help
Emerald 16 Mar 2009, 17:59
My husband and I purchased a condo unit about two years ago (our first
buy)on a mid rise building, we live on the top floor, about three months
later, we started noticing shadows of the studs and the nails throughout
the entire walls that are exposed to the exterior, our apartment is a
corner unit, also the ceiling has black shadows like there is water
residing up there, I called management, they did some repair in the roof (
so they said ) but this problems keeps getting worst by the day, I had an
inspector from the Health department in the county I lived and he said he
has never seen anything like that before, I was so worried because I though
It might be a case of mold and mildew, the inspector check my apartment and
said its definetly not mold. Now my question is, if is not mold then what
is it, is it a bad paint we used, or not enough paint, maybe the walls
needed a special kind of treatment before puting the paint? The exterior
material of the building we live is made of something called stuco. We
need advised as to what to do! thanks
sam 30 Oct 2009, 09:33
I will be texture coating and was wondering if drywall primer before the
spray would help or hinder the knockdown?
Blair 09 Nov 2009, 11:15
I run a salon and spa out of my home, recently my son has taken nail polish
and painted on my walls, as well he has sprayed a non-acetone polish
remover on the walls. SO my question is do i need to seal over these
places before i prime and repaint or do i even need to worry about them
soaking through the paint?
View all comments |



